Configuration File Options

The following page describes the configuration options available in MongoDB 3.2. For configuration file options for other versions of MongoDB, see the appropriate version of the MongoDB Manual.

Configuration File

You can configure mongod and mongos instances at startup using a configuration file. The configuration file contains settings that are equivalent to the mongod and mongos command-line options.

Using a configuration file makes managing mongod and mongos options easier, especially for large-scale deployments. You can also add comments to the configuration file to explain the server’s settings.

If you installed from a package and have started MongoDB using your system’s init script, you are already using a configuration file.

File Format

Important

Changed in version 2.6: MongoDB 2.6 introduces a YAML-based configuration file format. The 2.4 configuration file format remains for backward compatibility.

MongoDB configuration files use the YAML format [1].

The following sample configuration file contains several mongod settings that you may adapt to your local configuration:

Note

YAML does not support tab characters for indention: use spaces instead.

systemLog:
   destination: file
   path: "/var/log/mongodb/mongod.log"
   logAppend: true
storage:
   journal:
      enabled: true
processManagement:
   fork: true
net:
   bindIp: 127.0.0.1
   port: 27017
setParameter:
   enableLocalhostAuthBypass: false
...

The Linux package init scripts included in the official MongoDB packages depend on specific values for systemLog.path, storage.dbpath, and processManagement.fork. If you modify these settings in the default configuration file, mongod may not start.

[1]YAML is a superset of JSON.

Use the Configuration File

To start mongod or mongos using a config file, specify the config file with the --config option or the -f option, as in the following examples:

The following examples use the --config option for mongod and mongos:

mongod --config /etc/mongod.conf

mongos --config /etc/mongos.conf

You can also use the -f alias to specify the configuration file, as in the following:

mongod -f /etc/mongod.conf

mongos -f /etc/mongos.conf

If you installed from a package and have started MongoDB using your system’s init script, you are already using a configuration file.

Core Options

systemLog Options

systemLog:
   verbosity: <int>
   quiet: <boolean>
   traceAllExceptions: <boolean>
   syslogFacility: <string>
   path: <string>
   logAppend: <boolean>
   logRotate: <string>
   destination: <string>
   timeStampFormat: <string>
   component:
      accessControl:
         verbosity: <int>
      command:
         verbosity: <int>

      # COMMENT additional component verbosity settings omitted for brevity
systemLog.verbosity

Type: integer

Default: 0

Changed in version 3.0.

The default log message verbosity level for components. The verbosity level determines the amount of Informational and Debug messages MongoDB outputs.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.

To use a different verbosity level for a named component, use the component’s verbosity setting. For example, use the systemLog.component.accessControl.verbosity to set the verbosity level specifically for ACCESS components.

See the systemLog.component.<name>.verbosity settings for specific component verbosity settings.

For various ways to set the log verbosity level, see Configure Log Verbosity Levels.

systemLog.quiet

Type: boolean

Run the mongos or mongod in a quiet mode that attempts to limit the amount of output.

systemLog.quiet is not recommended for production systems as it may make tracking problems during particular connections much more difficult.

systemLog.traceAllExceptions

Type: boolean

Print verbose information for debugging. Use for additional logging for support-related troubleshooting.

systemLog.syslogFacility

Type: string

Default: user

The facility level used when logging messages to syslog. The value you specify must be supported by your operating system’s implementation of syslog. To use this option, you must enable the --syslog option.

systemLog.path

Type: string

The path of the log file to which mongod or mongos should send all diagnostic logging information, rather than the standard output or the host’s syslog. MongoDB creates the log file at the specified path.

The Linux package init scripts do not expect systemLog.path to change from the defaults. If you use the Linux packages and change systemLog.path, you will have to use your own init scripts and disable the built-in scripts.

systemLog.logAppend

Type: boolean

Default: False

When true, mongos or mongod appends new entries to the end of the existing log file when the mongos or mongod instance restarts. Without this option, mongod will back up the existing log and create a new file.

systemLog.logRotate

Type: string

Default: rename

New in version 3.0.0.

The behavior for the logRotate command. Specify either rename or reopen:

  • rename renames the log file.

  • reopen closes and reopens the log file following the typical Linux/Unix log rotate behavior. Use reopen when using the Linux/Unix logrotate utility to avoid log loss.

    If you specify reopen, you must also set systemLog.logAppend to true.

systemLog.destination

Type: string

The destination to which MongoDB sends all log output. Specify either file or syslog. If you specify file, you must also specify systemLog.path.

If you do not specify systemLog.destination, MongoDB sends all log output to standard output.

systemLog.timeStampFormat

Type: string

Default: iso8601-local

The time format for timestamps in log messages. Specify one of the following values:

Value Description
ctime Displays timestamps as Wed Dec 31 18:17:54.811.
iso8601-utc Displays timestamps in Coordinated Universal Time (UTC) in the ISO-8601 format. For example, for New York at the start of the Epoch: 1970-01-01T00:00:00.000Z
iso8601-local Displays timestamps in local time in the ISO-8601 format. For example, for New York at the start of the Epoch: 1969-12-31T19:00:00.000-0500

systemLog.component Options

systemLog:
   component:
      accessControl:
         verbosity: <int>
      command:
         verbosity: <int>

      # COMMENT some component verbosity settings omitted for brevity

      storage:
         verbosity: <int>
         journal:
            verbosity: <int>
      write:
         verbosity: <int>
systemLog.component.accessControl.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to access control. See ACCESS components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.command.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to commands. See COMMAND components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.control.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to control operations. See CONTROL components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.ftdc.verbosity

Type: integer

Default: 0

New in version 3.2.

The log message verbosity level for components related to diagnostic data collection operations. See FTDC components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.geo.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to geospatial parsing operations. See GEO components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.index.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to indexing operations. See INDEX components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.network.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to networking operations. See NETWORK components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.query.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to query operations. See QUERY components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.replication.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to replication. See REPL components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.sharding.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to sharding. See SHARDING components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.storage.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to storage. See STORAGE components.

If systemLog.component.storage.journal.verbosity is unset, systemLog.component.storage.verbosity level also applies to journaling components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.storage.journal.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to journaling. See JOURNAL components.

If systemLog.component.storage.journal.verbosity is unset, the journaling components have the same verbosity level as the parent storage components: i.e. either the systemLog.component.storage.verbosity level if set or the default verbosity level.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.
systemLog.component.write.verbosity

Type: integer

Default: 0

New in version 3.0.

The log message verbosity level for components related to write operations. See WRITE components.

The verbosity level can range from 0 to 5:

  • 0 is the MongoDB’s default log verbosity level, to include Informational messages.
  • 1 to 5 increases the verbosity level to include Debug messages.

processManagement Options

processManagement:
   fork: <boolean>
   pidFilePath: <string>
processManagement.fork

Type: boolean

Default: False

Enable a daemon mode that runs the mongos or mongod process in the background. By default mongos or mongod does not run as a daemon: typically you will run mongos or mongod as a daemon, either by using processManagement.fork or by using a controlling process that handles the daemonization process (e.g. as with upstart and systemd).

The Linux package init scripts do not expect processManagement.fork to change from the defaults. If you use the Linux packages and change processManagement.fork, you will have to use your own init scripts and disable the built-in scripts.

processManagement.pidFilePath

Type: string

Specifies a file location to hold the process ID of the mongos or mongod process where mongos or mongod will write its PID. This is useful for tracking the mongos or mongod process in combination with the --fork option. Without a specified processManagement.pidFilePath option, the process creates no PID file.

net Options

net:
   port: <int>
   bindIp: <string>
   maxIncomingConnections: <int>
   wireObjectCheck: <boolean>
   ipv6: <boolean>
   unixDomainSocket:
      enabled: <boolean>
      pathPrefix: <string>
      filePermissions: <int>
   http:
      enabled: <boolean>
      JSONPEnabled: <boolean>
      RESTInterfaceEnabled: <boolean>
   ssl:
      sslOnNormalPorts: <boolean>  # deprecated since 2.6
      mode: <string>
      PEMKeyFile: <string>
      PEMKeyPassword: <string>
      clusterFile: <string>
      clusterPassword: <string>
      CAFile: <string>
      CRLFile: <string>
      allowConnectionsWithoutCertificates: <boolean>
      allowInvalidCertificates: <boolean>
      allowInvalidHostnames: <boolean>
      disabledProtocols: <string>
      FIPSMode: <boolean>
net.port

Type: integer

Default: 27017

The TCP port on which the MongoDB instance listens for client connections.

net.bindIp

Type: string

Default: All interfaces.

Changed in version 2.6.0: The deb and rpm packages include a default configuration file (/etc/mongod.conf) that sets net.bindIp to 127.0.0.1.

The IP address that mongos or mongod binds to in order to listen for connections from applications. You may attach mongos or mongod to any interface. When attaching mongos or mongod to a publicly accessible interface, ensure that you have implemented proper authentication and firewall restrictions to protect the integrity of your database.

To bind to multiple IP addresses, enter a list of comma separated values.

net.maxIncomingConnections

Type: integer

Default: 65536

The maximum number of simultaneous connections that mongos or mongod will accept. This setting has no effect if it is higher than your operating system’s configured maximum connection tracking threshold.

Do not assign too low of a value to this option, or you will encounter errors during normal application operation.

This is particularly useful for a mongos if you have a client that creates multiple connections and allows them to timeout rather than closing them.

In this case, set maxIncomingConnections to a value slightly higher than the maximum number of connections that the client creates, or the maximum size of the connection pool.

This setting prevents the mongos from causing connection spikes on the individual shards. Spikes like these may disrupt the operation and memory allocation of the sharded cluster.

net.wireObjectCheck

Type: boolean

Default: True

When true, the mongod or mongos instance validates all requests from clients upon receipt to prevent clients from inserting malformed or invalid BSON into a MongoDB database.

For objects with a high degree of sub-document nesting, net.wireObjectCheck can have a small impact on performance.

net.ipv6

Type: boolean

Default: False

Removed in version 3.0.

Enable or disable IPv6 support and allows mongos or mongod to connect to the MongoDB instance using an IPv6 network. Prior to MongoDB 3.0, you had to specify net.ipv6 to use IPv6. In MongoDB 3.0 and later, IPv6 is always enabled.

net.unixDomainSocket Options

net:
   unixDomainSocket:
      enabled: <boolean>
      pathPrefix: <string>
      filePermissions: <int>
net.unixDomainSocket.enabled

Type: boolean

Default: True

Enable or disable listening on the UNIX domain socket. net.unixDomainSocket.enabled applies only to Unix-based systems.

When net.unixDomainSocket.enabled is true, mongos or mongod listens on the UNIX socket.

The mongos or mongod process always listens on the UNIX socket unless one of the following is true:

  • net.unixDomainSocket.enabled is false
  • --nounixsocket is set. The command line option takes precedence over the configuration file setting.
  • net.bindIp is not set
  • net.bindIp does not specify 127.0.0.1

New in version 2.6: mongos or mongod installed from official .deb and .rpm packages have the bind_ip configuration set to 127.0.0.1 by default.

net.unixDomainSocket.pathPrefix

Type: string

Default: /tmp

The path for the UNIX socket. net.unixDomainSocket.pathPrefix applies only to Unix-based systems.

If this option has no value, the mongos or mongod process creates a socket with /tmp as a prefix. MongoDB creates and listens on a UNIX socket unless one of the following is true:

  • net.unixDomainSocket.enabled is false
  • --nounixsocket is set
  • net.bindIp is not set
  • net.bindIp does not specify 127.0.0.1
net.unixDomainSocket.filePermissions

Type: int

Default: 0700

Sets the permission for the UNIX domain socket file.

net.unixDomainSocket.filePermissions applies only to Unix-based systems.

net.http Options

net:
   http:
      enabled: <boolean>
      JSONPEnabled: <boolean>
      RESTInterfaceEnabled: <boolean>

Warning

Ensure that the HTTP status interface, the REST API, and the JSON API are all disabled in production environments to prevent potential data exposure and vulnerability to attackers.

net.http.enabled

Type: boolean

Default: False

Deprecated since version 3.2: HTTP interface for MongoDB

Enable or disable the HTTP interface. Enabling the interface can increase network exposure.

Leave the HTTP interface disabled for production deployments. If you do enable this interface, you should only allow trusted clients to access this port. See Firewalls.

Note

  • While MongoDB Enterprise does support Kerberos authentication, Kerberos is not supported in HTTP status interface in any version of MongoDB.

New in version 2.6.

net.http.JSONPEnabled

Type: boolean

Default: False

Enable or disable JSONP access via an HTTP interface. Enabling the interface can increase network exposure. The net.http.JSONPEnabled option enables the HTTP interface, even if the HTTP interface option is disabled.

Deprecated since version 3.2: HTTP interface for MongoDB

The net.http.JSONPEnabled setting is available only for mongod.

net.http.RESTInterfaceEnabled

Type: boolean

Default: False

Enable or disable the simple REST API. Enabling the REST API enables the HTTP interface, even if the HTTP interface option is disabled, and as a result can increase network exposure.

Deprecated since version 3.2: HTTP interface for MongoDB

The net.http.RESTInterfaceEnabled setting is available only for mongod.

net.ssl Options

net:
   ssl:
      sslOnNormalPorts: <boolean>  # deprecated since 2.6
      mode: <string>
      PEMKeyFile: <string>
      PEMKeyPassword: <string>
      clusterFile: <string>
      clusterPassword: <string>
      CAFile: <string>
      CRLFile: <string>
      allowConnectionsWithoutCertificates: <boolean>
      allowInvalidCertificates: <boolean>
      allowInvalidHostnames: <boolean>
      disabledProtocols: <string>
      FIPSMode: <boolean>
net.ssl.sslOnNormalPorts

Type: boolean

Deprecated since version 2.6.

Enable or disable TLS/SSL for mongos or mongod.

With net.ssl.sslOnNormalPorts, a mongos or mongod requires TLS/SSL encryption for all connections on the default MongoDB port, or the port specified by --port. By default, --sslOnNormalPorts is disabled.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.mode

Type: string

New in version 2.6.

Enable or disable TLS/SSL or mixed TLS/SSL used for all network connections. The argument to the net.ssl.mode setting can be one of the following:

Value Description
disabled The server does not use TLS/SSL.
allowSSL Connections between servers do not use TLS/SSL. For incoming connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
preferSSL Connections between servers use TLS/SSL. For incoming connections, the server accepts both TLS/SSL and non-TLS/non-SSL.
requireSSL The server uses and accepts only TLS/SSL encrypted connections.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.PEMKeyFile

Type: string

The .pem file that contains both the TLS/SSL certificate and key. Specify the file name of the .pem file using relative or absolute paths.

You must specify net.ssl.PEMKeyFile when TLS/SSL is enabled.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.PEMKeyPassword

Type: string

The password to de-crypt the certificate-key file (i.e. PEMKeyFile). Use the net.ssl.PEMKeyPassword option only if the certificate-key file is encrypted. In all cases, the mongos or mongod will redact the password from all logging and reporting output.

Changed in version 2.6: If the private key in the PEM file is encrypted and you do not specify the net.ssl.PEMKeyPassword option, the mongos or mongod will prompt for a passphrase. See SSL Certificate Passphrase.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.clusterFile

Type: string

New in version 2.6.

The .pem file that contains the x.509 certificate-key file for membership authentication for the cluster or replica set.

If net.ssl.clusterFile does not specify the .pem file for internal cluster authentication, the cluster uses the .pem file specified in the PEMKeyFile setting.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.clusterPassword

Type: string

New in version 2.6.

The password to de-crypt the x.509 certificate-key file specified with --sslClusterFile. Use the net.ssl.clusterPassword option only if the certificate-key file is encrypted. In all cases, the mongos or mongod will redact the password from all logging and reporting output.

If the x.509 key file is encrypted and you do not specify the net.ssl.clusterPassword option, the mongos or mongod will prompt for a passphrase. See SSL Certificate Passphrase.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.CAFile

Type: string

New in version 2.4.

The .pem file that contains the root certificate chain from the Certificate Authority. Specify the file name of the .pem file using relative or absolute paths.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Warning

If the --sslCAFile option and its target file are not specified, x.509 client and member authentication will not function. mongod, and mongos in sharded systems, will not be able to verify the certificates of processes connecting to it against the trusted certificate authority (CA) that issued them, breaking the certificate chain.

As of version 2.6.4, mongod will not start with x.509 authentication enabled if the CA file is not specified.

net.ssl.CRLFile

Type: string

New in version 2.4.

The the .pem file that contains the Certificate Revocation List. Specify the file name of the .pem file using relative or absolute paths.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.allowConnectionsWithoutCertificates

Type: boolean

New in version 2.4.

Changed in version 3.0.0: net.ssl.weakCertificateValidation became net.ssl.allowConnectionsWithoutCertificates. For compatibility, MongoDB processes continue to accept net.ssl.weakCertificateValidation, but all users should update their configuration files.

Enable or disable the requirement for TLS/SSL certificate validation that CAFile enables. With the net.ssl.allowConnectionsWithoutCertificates option, the mongos or mongod will accept connections when the client does not present a certificate when establishing the connection.

If the client presents a certificate and the mongos or mongod has net.ssl.allowConnectionsWithoutCertificates enabled, the mongos or mongod will validate the certificate using the root certificate chain specified by CAFile and reject clients with invalid certificates.

Use the net.ssl.allowConnectionsWithoutCertificates option if you have a mixed deployment that includes clients that do not or cannot present certificates to the mongos or mongod.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.allowInvalidCertificates

Type: boolean

New in version 2.6.

Enable or disable the validation checks for TLS/SSL certificates on other servers in the cluster and allows the use of invalid certificates.

When using the net.ssl.allowInvalidCertificates setting, MongoDB logs a warning regarding the use of the invalid certificate.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.allowInvalidHostnames

Type: boolean

Default: False

New in version 3.0.

When net.ssl.allowInvalidHostnames is true, MongoDB disables the validation of the hostnames in TLS/SSL certificates, allowing mongod to connect to MongoDB instances if the hostname their certificates do not match the specified hostname.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

net.ssl.disabledProtocols

Type: string

New in version 3.0.7.

Prevents a MongoDB server running with SSL from accepting incoming connections that use a specific protocol or protocols. net.ssl.disabledProtocols recognizes the following protocols: TLS1_0, TLS1_1, and TLS1_2. Specifying an unrecognized protocol will prevent the server from starting.

To specify multiple protocols, use a comma separated list of protocols.

Members of replica sets and sharded clusters must speak at least one protocol in common.

net.ssl.FIPSMode

Type: boolean

New in version 2.4.

Enable or disable the use of the FIPS mode of the installed OpenSSL library for the mongos or mongod. Your system must have a FIPS compliant OpenSSL library to use the net.ssl.FIPSMode option.

Note

FIPS-compatible SSL is available only in MongoDB Enterprise. See Configure MongoDB for FIPS for more information.

security Options

security:
   keyFile: <string>
   clusterAuthMode: <string>
   authorization: <string>
   javascriptEnabled:  <boolean>
   sasl:
      hostName: <string>
      serviceName: <string>
      saslauthdSocketPath: <string>
   enableEncryption: <boolean>
   encryptionCipherMode: <string>
   encryptionKeyFile: <string>
   kmip:
      keyIdentifier: <string>
      rotateMasterKey: <boolean>
      serverName: <string>
      port: <string>
      clientCertificateFile: <string>
      clientCertificatePassword: <string>
      serverCAFile: <string>
security.keyFile

Type: string

The path to a key file that stores the shared secret that MongoDB instances use to authenticate to each other in a sharded cluster or replica set. keyFile implies security.authorization. See Internal Authentication for more information.

security.clusterAuthMode

Type: string

Default: keyFile

New in version 2.6.

The authentication mode used for cluster authentication. If you use internal x.509 authentication, specify so here. This option can have one of the following values:

Value Description
keyFile Use a keyfile for authentication. Accept only keyfiles.
sendKeyFile For rolling upgrade purposes. Send a keyfile for authentication but can accept both keyfiles and x.509 certificates.
sendX509 For rolling upgrade purposes. Send the x.509 certificate for authentication but can accept both keyfiles and x.509 certificates.
x509 Recommended. Send the x.509 certificate for authentication and accept only x.509 certificates.

Changed in version 3.0: Most MongoDB distributions now include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

security.authorization

Type: string

Default: disabled

Enable or disable Role-Based Access Control (RBAC) to govern each user’s access to database resources and operations.

Set this option to one of the following:

Value Description
enabled A user can access only the database resources and actions for which they have been granted privileges.
disabled A user can access any database and perform any action.

See Role-Based Access Control for more information.

The security.authorization setting is available only for mongod.

security.javascriptEnabled

Type: boolean

Default: True

Enables or disables the server-side JavaScript execution. When disabled, you cannot use operations that perform server-side execution of JavaScript code, such as the $where query operator, mapReduce command and the db.collection.mapReduce() method, group command and the db.collection.group() method.

Key Management Configuration Options

security:
   enableEncryption: <boolean>
   encryptionCipherMode: <string>
   encryptionKeyFile: <string>
   kmip:
      keyIdentifier: <string>
      rotateMasterKey: <boolean>
      serverName: <string>
      port: <string>
      clientCertificateFile: <string>
      clientCertificatePassword: <string>
      serverCAFile: <string>
security.enableEncryption

Type: boolean

Default: False

New in version 3.2: Enables encryption for the WiredTiger storage engine. You must set to true to pass in encryption keys and configurations.

Enterprise Feature

Available in MongoDB Enterprise only.

security.encryptionCipherMode

Type: string

Default: AES256-CBC

New in version 3.2.

The cipher mode to use for encryption at rest:

Mode Description
AES256-CBC 256-bit Advanced Encryption Standard in Cipher Block Chaining Mode
AES256-GCM 256-bit Advanced Encryption Standard in Galois/Counter Mode

Enterprise Feature

Available in MongoDB Enterprise only.

security.encryptionKeyFile

Type: string

New in version 3.2.

The path to the local keyfile when managing keys via process other than KMIP. Only set when managing keys via process other than KMIP. If data is already encrypted using KMIP, MongoDB will throw an error.

Requires security.enableEncryption to be true.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.keyIdentifier

Type: string

New in version 3.2.

Unique KMIP identifier for an existing key within the KMIP server. Include to use the key associated with the identifier as the system key. You can only use the setting the first time you enable encryption for the mongod instance. Requires security.enableEncryption to be true.

If unspecified, MongoDB will request that the KMIP server create a new key to utilize as the system key.

If the KMIP server cannot locate a key with the specified identifier or the data is already encrypted with a key, MongoDB will throw an error.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.rotateMasterKey

Type: boolean

Default: False

New in version 3.2.

If true, rotate the master key and re-encrypt the internal keystore.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.serverName

Type: string

New in version 3.2.

Hostname or IP address of key management solution running a KMIP server. Requires security.enableEncryption to be true.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.port

Type: string

Default: 5696

New in version 3.2.

Port number the KMIP server is listening on. Requires that a security.kmip.serverName be provided. Requires security.enableEncryption to be true.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.clientCertificateFile

Type: string

New in version 3.2.

String containing the path to the client certificate used for authenticating MongoDB to the KMIP server. Requires that a security.kmip.serverName be provided.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.clientCertificatePassword

Type: string

New in version 3.2.

The password to decrypt the client certificate (i.e. security.kmip.clientCertificateFile), used to authenticate MongoDB to the KMIP server. Use the option only if the certificate is encrypted.

Enterprise Feature

Available in MongoDB Enterprise only.

security.kmip.serverCAFile

Type: string

New in version 3.2.

Path to CA File. Used for validating secure client connection to KMIP server.

Enterprise Feature

Available in MongoDB Enterprise only.

security.sasl Options

security:
   sasl:
      hostName: <string>
      serviceName: <string>
      saslauthdSocketPath: <string>
security.sasl.hostName

Type: string

A fully qualified server domain name for the purpose of configuring SASL and Kerberos authentication. The SASL hostname overrides the hostname only for the configuration of SASL and Kerberos.

For mongo shell and other MongoDB tools to connect to the new hostName, see the gssapiHostName option in the mongo shell and other tools.

security.sasl.serviceName

Type: string

Registered name of the service using SASL. This option allows you to override the default Kerberos service name component of the Kerberos principal name, on a per-instance basis. If unspecified, the default value is mongodb.

MongoDB permits setting this option only at startup. The setParameter can not change this setting.

This option is available only in MongoDB Enterprise.

Important

Ensure that your driver supports alternate service names. For mongo shell and other MongoDB tools to connect to the new serviceName, see the gssapiServiceName option.

security.sasl.saslauthdSocketPath

Type: string

The path to the UNIX domain socket file for saslauthd.

setParameter Option

setParameter

Set MongoDB parameter or parameters described in MongoDB Server Parameters

To set parameters in the YAML configuration file, use the following format:

setParameter:
   <parameter1>: <value1>
   <parameter2>: <value2>

For example, to specify the enableLocalhostAuthBypass in the configuration file:

setParameter:
   enableLocalhostAuthBypass: false

storage Options

storage:
   dbPath: <string>
   indexBuildRetry: <boolean>
   repairPath: <string>
   journal:
      enabled: <boolean>
      commitIntervalMs: <num>
   directoryPerDB: <boolean>
   syncPeriodSecs: <int>
   engine: <string>
   mmapv1:
      preallocDataFiles: <boolean>
      nsSize: <int>
      quota:
         enforced: <boolean>
         maxFilesPerDB: <int>
      smallFiles: <boolean>
      journal:
         debugFlags: <int>
         commitIntervalMs: <num>
   wiredTiger:
      engineConfig:
         cacheSizeGB: <number>
         journalCompressor: <string>
         directoryForIndexes: <boolean>
      collectionConfig:
         blockCompressor: <string>
      indexConfig:
         prefixCompression: <boolean>
   inMemory:
      engineConfig:
         inMemorySizeGB: <number>
storage.dbPath

Type: string

Default: /data/db on Linux and OS X, \data\db on Windows

The directory where the mongod instance stores its data.

If you installed MongoDB using a package management system, check the /etc/mongod.conf file provided by your packages to see the directory is specified.

The storage.dbPath setting is available only for mongod.

The Linux package init scripts do not expect storage.dbPath to change from the defaults. If you use the Linux packages and change storage.dbPath, you will have to use your own init scripts and disable the built-in scripts.

storage.indexBuildRetry

Type: boolean

Default: True

Specifies whether mongod rebuilds incomplete indexes on the next start up. This applies in cases where mongod restarts after it has shut down or stopped in the middle of an index build. In such cases, mongod always removes any incomplete indexes, and then, by default, attempts to rebuild them. To stop mongod from rebuilding indexes, set this option to false.

The storage.indexBuildRetry setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.repairPath

Type: string

Default: A _tmp_repairDatabase_<num> directory under the dbPath.

The working directory that MongoDB will use during the --repair operation. When --repair completes, the storage.repairPath directory is empty, and dbPath contains the repaired files.

The storage.repairPath setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.journal.enabled

Type: boolean

Default: true on 64-bit systems, false on 32-bit systems

Enable or disable the durability journal to ensure data files remain valid and recoverable. This option applies only when you specify the --dbpath option. The mongod enables journaling by default on 64-bit builds of versions after 2.0.

The storage.journal.enabled setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.journal.commitIntervalMs

Type: number

Default: 100 or 30

New in version 3.2.

The maximum amount of time in milliseconds that the mongod process allows between journal operations. Values can range from 1 to 500 milliseconds. Lower values increase the durability of the journal, at the expense of disk performance. The default journal commit interval is 100 milliseconds.

On MMAPv1, if the journal is on a different block device (e.g. physical volume, RAID device, or LVM volume) than the data files, the default journal commit interval is 30 milliseconds. Additionally, on MMAPv1, when a write operation with j:true is pending, mongod will reduce commitIntervalMs to a third of the set value.

On WiredTiger, the default journal commit interval is 100 milliseconds. Additionally, a write with j:true will cause an immediate sync of the journal.

The storage.journal.commitIntervalMs setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.directoryPerDB

Type: boolean

Default: False

When true, MongoDB uses a separate directory to store data for each database. The directories are under the storage.dbPath directory, and each subdirectory name corresponds to the database name.

Changed in version 3.0: To change the storage.directoryPerDB option for existing deployments, you must restart the mongod instances with the new storage.directoryPerDB value and a new data directory (storage.dbPath value), and then repopulate the data.

  • For standalone instances, you can use mongodump on the existing instance, stop the instance, restart with the new storage.directoryPerDB value and a new data directory, and use mongorestore to populate the new data directory.
  • For replica sets, you can update in a rolling manner by stopping a secondary member, restart with the new storage.directoryPerDB value and a new data directory, and use initial sync to populate the new data directory. To update all members, start with the secondary members first. Then step down the primary, and update the stepped-down member.

The storage.directoryPerDB setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.syncPeriodSecs

Type: number

Default: 60

The amount of time that can pass before MongoDB flushes data to the data files via an fsync operation.

Do not set this value on production systems. In almost every situation, you should use the default setting.

Warning

If you set storage.syncPeriodSecs to 0, MongoDB will not sync the memory mapped files to disk.

The mongod process writes data very quickly to the journal and lazily to the data files. storage.syncPeriodSecs has no effect on the journal files or journaling.

The serverStatus command reports the background flush thread’s status via the backgroundFlushing field.

The storage.syncPeriodSecs setting is available only for mongod.

Not available for mongod instances that use the in-memory storage engine.

storage.engine

Default: wiredTiger

New in version 3.0.

Changed in version 3.2: Starting in MongoDB 3.2, wiredTiger is the default.

The storage engine for the mongod database. Available values include:

Value Description
mmapv1 To specify the MMAPv1 Storage Engine.
wiredTiger To specify the WiredTiger Storage Engine.
inMemory

To specify the In-Memory Storage Engine.

New in version 3.2: Available in MongoDB Enterprise only.

If you attempt to start a mongod with a storage.dbPath that contains data files produced by a storage engine other than the one specified by storage.engine, mongod will refuse to start.

storage.mmapv1 Options

storage:
   mmapv1:
      preallocDataFiles: <boolean>
      nsSize: <int>
      quota:
         enforced: <boolean>
         maxFilesPerDB: <int>
      smallFiles: <boolean>
      journal:
         debugFlags: <int>
         commitIntervalMs: <num>
storage.mmapv1.preallocDataFiles

Type: boolean

Default: True

Deprecated since version 2.6.

Enable or disable the preallocation of data files. Currently the default. Exists for future compatibility and clarity.

The storage.mmapv1.preallocDataFiles setting is available only for mongod.

storage.mmapv1.nsSize

Type: integer

Default: 16

The default size for namespace files, which are files that end in .ns. Each collection and index counts as a namespace.

Use this setting to control size for newly created namespace files. This option has no impact on existing files. The maximum size for a namespace file is 2047 megabytes. The default value of 16 megabytes provides for approximately 24,000 namespaces.

The storage.mmapv1.nsSize setting is available only for mongod.

storage.mmapv1.quota.enforced

Type: Boolean

Default: false

Enable or disable the enforcement of a maximum limit for the number data files each database can have. When running with the storage.mmapv1.quota.enforced option, MongoDB has a maximum of 8 data files per database. Adjust the quota with storage.quota.maxFilesPerDB.

The storage.mmapv1.quota.enforced setting is available only for mongod.

storage.mmapv1.quota.maxFilesPerDB

Type: integer

Default: 8

The limit on the number of data files per database. storage.mmapv1.quota.maxFilesPerDB option requires that you set storage.quota.enforced.

The storage.mmapv1.quota.maxFilesPerDB setting is available only for mongod.

storage.mmapv1.smallFiles

Type: boolean

Default: False

When true, MongoDB uses a smaller default file size. The storage.mmapv1.smallFiles option reduces the initial size for data files and limits the maximum size to 512 megabytes. storage.mmapv1.smallFiles also reduces the size of each journal file from 1 gigabyte to 128 megabytes. Use storage.mmapv1.smallFiles if you have a large number of databases that each holds a small quantity of data.

The storage.mmapv1.smallFiles option can lead the mongod instance to create a large number of files, which can affect performance for larger databases.

The storage.mmapv1.smallFiles setting is available only for mongod.

storage.mmapv1.journal.debugFlags

Type: integer

Provides functionality for testing. Not for general use, and will affect data file integrity in the case of abnormal system shutdown.

The storage.mmapv1.journal.debugFlags option is available only for mongod.

storage.mmapv1.journal.commitIntervalMs

Type: number

Deprecated since version 3.2: MongoDB 3.2 deprecates the storage.mmapv1.journal.commitIntervalMs setting. Use storage.journal.commitIntervalMs instead.

The deprecated setting acts as an alias to the new storage.journal.commitIntervalMS setting and applies to either the MMAPv1 or the WiredTiger storage engine.

storage.wiredTiger Options

storage:
   wiredTiger:
      engineConfig:
         cacheSizeGB: <number>
         journalCompressor: <string>
         directoryForIndexes: <boolean>
      collectionConfig:
         blockCompressor: <string>
      indexConfig:
         prefixCompression: <boolean>
storage.wiredTiger.engineConfig.cacheSizeGB

New in version 3.0.

The maximum size of the internal cache that WiredTiger will use for all data.

With WiredTiger, MongoDB utilizes both the WiredTiger internal cache and the filesystem cache.

Changed in version 3.2: Starting in MongoDB 3.2, the WiredTiger internal cache, by default, will use the larger of either:

  • 60% of RAM minus 1 GB, or
  • 1 GB.

For systems with up to 10 GB of RAM, the new default setting is less than or equal to the 3.0 default setting (For MongoDB 3.0, the WiredTiger internal cache uses either 1 GB or half of the installed physical RAM, whichever is larger).

For systems with more than 10 GB of RAM, the new default setting is greater than the 3.0 setting.

Via the filesystem cache, MongoDB automatically uses all free memory that is not used by the WiredTiger cache or by other processes. Data in the filesystem cache is compressed.

Avoid increasing the WiredTiger internal cache size above its default value.

Note

The storage.wiredTiger.engineConfig.cacheSizeGB limits the size of the WiredTiger internal cache. The operating system will use the available free memory for filesystem cache, which allows the compressed MongoDB data files to stay in memory. In addition, the operating system will use any free RAM to buffer file system blocks and file system cache.

To accommodate the additional consumers of RAM, you may have to decrease WiredTiger internal cache size.

The default WiredTiger internal cache size value assumes that there is a single mongod instance per machine. If a single machine contains multiple MongoDB instances, then you should decrease the setting to accommodate the other mongod instances.

If you run mongod in a container (e.g. lxc, cgroups, Docker, etc.) that does not have access to all of the RAM available in a system, you must set storage.wiredTiger.engineConfig.cacheSizeGB to a value less than the amount of RAM available in the container. The exact amount depends on the other processes running in the container.

storage.wiredTiger.engineConfig.journalCompressor

Default: snappy

New in version 3.0.0.

The type of compression to use to compress WiredTiger journal data.

Available compressors are:

storage.wiredTiger.engineConfig.directoryForIndexes

Type: boolean

Default: false

New in version 3.0.0.

When storage.wiredTiger.engineConfig.directoryForIndexes is true, mongod stores indexes and collections in separate subdirectories under the data (i.e. storage.dbPath) directory. Specifically, mongod stores the indexes in a subdirectory named index and the collection data in a subdirectory named collection.

By using a symbolic link, you can specify a different location for the indexes. Specifically, when mongod instance is not running, move the index subdirectory to the destination and create a symbolic link named index under the data directory to the new destination.

storage.wiredTiger.collectionConfig.blockCompressor

Default: snappy

New in version 3.0.0.

The default type of compression to use to compress collection data. You can override this on a per-collection basis when creating collections.

Available compressors are:

storage.wiredTiger.collectionConfig.blockCompressor affects all collections created. If you change the value of storage.wiredTiger.collectionConfig.blockCompressor on an existing MongoDB deployment, all new collections will use the specified compressor. Existing collections will continue to use the compressor specified when they were created, or the default compressor at that time.

storage.wiredTiger.indexConfig.prefixCompression

Default: true

New in version 3.0.0.

Enables or disables prefix compression for index data.

Specify true for storage.wiredTiger.indexConfig.prefixCompression to enable prefix compression for index data, or false to disable prefix compression for index data.

The storage.wiredTiger.indexConfig.prefixCompression setting affects all indexes created. If you change the value of storage.wiredTiger.indexConfig.prefixCompression on an existing MongoDB deployment, all new indexes will use prefix compression. Existing indexes are not affected.

storage.inmemory Options

storage:
   inMemory:
      engineConfig:
         inMemorySizeGB: <number>
storage.inMemory.engineConfig.inMemorySizeGB

Type: number

Default: 50% of physical RAM less 1 GB

New in version 3.2.

Maximum amount of memory to allocate for in-memory storage engine data, including indexes, oplog if the mongod is part of replica set, replica set or sharded cluster metadata, etc.

By default, the in-memory storage engine uses 50% of physical RAM minus 1 GB.

Enterprise Feature

Available in MongoDB Enterprise only.

operationProfiling Options

operationProfiling:
   slowOpThresholdMs: <int>
   mode: <string>
operationProfiling.slowOpThresholdMs

Type: integer

Default: 100

The threshold in milliseconds at which the database profiler considers a query slow. MongoDB records all slow queries to the log, even when the database profiler is off. When the profiler is on, it writes to the system.profile collection. See the profile command for more information on the database profiler.

The operationProfiling.slowOpThresholdMs setting is available only for mongod.

operationProfiling.mode

Type: string

Default: off

The level of database profiling, which inserts information about operation performance into the system.profile collection. Specify one of the following levels:

Level Setting
off Off. No profiling.
slowOp On. Only includes slow operations.
all On. Includes all operations.

Database profiling can impact database performance. Enable this option only after careful consideration.

The operationProfiling.mode setting is available only for mongod.

replication Options

replication:
   oplogSizeMB: <int>
   replSetName: <string>
   secondaryIndexPrefetch: <string>
   enableMajorityReadConcern: <boolean>
replication.oplogSizeMB

Type: integer

The maximum size in megabytes for the replication operation log (i.e., the oplog). The mongod process creates an oplog based on the maximum amount of space available. For 64-bit systems, the oplog is typically 5% of available disk space. Once the mongod has created the oplog for the first time, changing the replication.oplogSizeMB option will not affect the size of the oplog.

See Oplog Size for more information.

The replication.oplogSizeMB setting is available only for mongod.

replication.replSetName

Type: string

The name of the replica set that the mongod is part of. All hosts in the replica set must have the same set name.

If your application connects to more than one replica set, each set should have a distinct name. Some drivers group replica set connections by replica set name.

The replication.replSetName setting is available only for mongod.

replication.secondaryIndexPrefetch

Type: string

Default: all

Storage Engine Specific Feature

replication.secondaryIndexPrefetch is only available with the mmapv1 storage engine.

The indexes that secondary members of a replica set load into memory before applying operations from the oplog. By default secondaries load all indexes related to an operation into memory before applying operations from the oplog.

Set this setting to one of the following:

Value Description
none Secondaries do not load indexes into memory.
all Secondaries load all indexes related to an operation.
_id_only Secondaries load no additional indexes into memory beyond the already existing _id index.

The replication.secondaryIndexPrefetch setting is available only for mongod.

replication.enableMajorityReadConcern

Type: boolean

Default: False

New in version 3.2.

Enables read concern level of "majority".

sharding Options

sharding:
   clusterRole: <string>
   archiveMovedChunks: <boolean>
sharding.clusterRole

Type: string

The role that the mongod instance has in the sharded cluster. Set this setting to one of the following:

Value Description
configsvr Start this instance as a config server. The instance starts on port 27019 by default.
shardsvr Start this instance as a shard. The instance starts on port 27018 by default.

The sharding.clusterRole setting is available only for mongod.

sharding.archiveMovedChunks

Type: boolean

Changed in version 3.2: Starting in 3.2, MongoDB uses false as the default.

During chunk migration, a shard does not save documents migrated from the shard.

auditLog Options

Note

Available only in MongoDB Enterprise.

auditLog:
   destination: <string>
   format: <string>
   path: <string>
   filter: <string>
auditLog.destination

Type: string

New in version 2.6.

When set, auditLog.destination enables auditing and specifies where mongos or mongod sends all audit events.

auditLog.destination can have one of the following values:

Value Description
syslog

Output the audit events to syslog in JSON format. Not available on Windows. Audit messages have a syslog severity level of info and a facility level of user.

The syslog message limit can result in the truncation of audit messages. The auditing system will neither detect the truncation nor error upon its occurrence.

console Output the audit events to stdout in JSON format.
file Output the audit events to the file specified in --auditPath in the format specified in --auditFormat.

Note

Available only in MongoDB Enterprise.

auditLog.format

Type: string

New in version 2.6.

The format of the output file for auditing if destination is file. The auditLog.format option can have one of the following values:

Value Description
JSON Output the audit events in JSON format to the file specified in --auditPath.
BSON Output the audit events in BSON binary format to the file specified in --auditPath.

Printing audit events to a file in JSON format degrades server performance more than printing to a file in BSON format.

Note

Available only in MongoDB Enterprise.

auditLog.path

Type: string

New in version 2.6.

The output file for auditing if destination has value of file. The auditLog.path option can take either a full path name or a relative path name.

Note

Available only in MongoDB Enterprise.

auditLog.filter

Type: string representation of a document

New in version 2.6.

The filter to limit the types of operations the audit system records. The option takes a string representation of a query document of the form:

{ <field1>: <expression1>, ... }

The <field> can be any field in the audit message, including fields returned in the param document. The <expression> is a query condition expression.

To specify an audit filter, enclose the filter document in single quotes to pass the document as a string.

To specify the audit filter in a configuration file, you must use the YAML format of the configuration file.

Note

Available only in MongoDB Enterprise.

snmp Options

snmp:
   subagent: <boolean>
   master: <boolean>
snmp.subagent

Type: boolean

When snmp.subagent is true, SNMP runs as a subagent. For more information, see Monitor MongoDB With SNMP on Linux.

The snmp.subagent setting is available only for mongod.

snmp.master

Type: boolean

When snmp.master is true, SNMP runs as a master. For more information, see Monitor MongoDB With SNMP on Linux.

The snmp.master setting is available only for mongod.

Text Search Options

basisTech
basisTech.rootDirectory

Type: string

New in version 3.2.

Specify the path to the root directory of the Basis Technology Rosette Linguistics Platform installation to support additional languages for text search operations.

Enterprise Feature

Available in MongoDB Enterprise only.

mongos-only Options

replication:
   localPingThresholdMs: <int>

sharding:
   autoSplit: <boolean>
   configDB: <string>
   chunkSize: <int>
replication.localPingThresholdMs

Type: integer

Default: 15

The ping time, in milliseconds, that mongos uses to determine which secondary replica set members to pass read operations from clients. The default value of 15 corresponds to the default value in all of the client drivers.

When mongos receives a request that permits reads to secondary members, the mongos will:

  • Find the member of the set with the lowest ping time.

  • Construct a list of replica set members that is within a ping time of 15 milliseconds of the nearest suitable member of the set.

    If you specify a value for the replication.localPingThresholdMs option, mongos will construct the list of replica members that are within the latency allowed by this value.

  • Select a member to read from at random from this list.

The ping time used for a member compared by the replication.localPingThresholdMs setting is a moving average of recent ping times, calculated at most every 10 seconds. As a result, some queries may reach members above the threshold until the mongos recalculates the average.

See the Read Preference for Replica Sets section of the read preference documentation for more information.

sharding.autoSplit

Type: boolean

Default: True

Enables or disables the automatic splitting of chunks for sharded collections. If sharding.autoSplit is false on all mongos instances, MongoDB does not create new chunks as the data in a collection grows.

Because any mongos in a cluster can create a split, to totally disable splitting in a cluster, you must set sharding.autoSplit to false on all mongos.

Warning

With auto-splitting disabled, the data in your sharded cluster may become imbalanced over time. Disable with caution.

sharding.configDB

Type: string

Changed in version 3.2.

The configuration servers for the sharded cluster.

Starting in MongoDB 3.2, config servers for sharded clusters can be deployed as a replica set. The replica set config servers must run the WiredTiger storage engine. MongoDB 3.2 deprecates the use of three mirrored mongod instances for config servers.

Specify the config server replica set name and the hostname and port of at least one of the members of the config server replica set.

sharding:
  configDB: <configReplSetName>/cfg1.example.net:27017, cfg2.example.net:27017,...

The mongos instances for the sharded cluster must specify the same config server replica set name but can specify hostname and port of different members of the replica set.

If using the deprecated mirrored instances, specify the hostnames and ports of the three mongod instances. The mongos instances must specify the same config string.

sharding.chunkSize

Type: integer

Default: 64

The size in megabytes of each chunk in the sharded cluster. A size of 64 megabytes is ideal in most deployments: larger chunk size can lead to uneven data distribution; smaller chunk size can lead to inefficient movement of chunks between nodes.

sharding.chunkSize affects chunk size only when you initialize the cluster for the first time. If you later modify the option, the new value has no effect. See the Modify Chunk Size in a Sharded Cluster procedure if you need to change the chunk size on an existing sharded cluster.

sharding.configsvrMode

Type: string

New in version 3.2.

If set to sccc, indicates that the config servers are deployed as three mirrored mongod instances, even if one or more config servers is also a member of a replica set. configsvrMode only accepts the value sccc.

If unset, config servers running as replica sets expect to use the “config server replica set” protocol for writing to config servers, rather than the “mirrored mongod” write protocol.

Windows Service Options

processManagement:
   windowsService:
      serviceName: <string>
      displayName: <string>
      description: <string>
      serviceUser: <string>
      servicePassword: <string>
processManagement.windowsService.serviceName

Type: string

Default: MongoDB

The service name of mongos or mongod when running as a Windows Service. Use this name with the net start <name> and net stop <name> operations.

You must use processManagement.windowsService.serviceName in conjunction with either the --install or --remove install option.

processManagement.windowsService.displayName

Type: string

Default: MongoDB

The name listed for MongoDB on the Services administrative application.

processManagement.windowsService.description

Type: string

Default: MongoDB Server

Run mongos or mongod service description.

You must use processManagement.windowsService.description in conjunction with the --install option.

For descriptions that contain spaces, you must enclose the description in quotes.

processManagement.windowsService.serviceUser

Type: string

The mongos or mongod service in the context of a certain user. This user must have “Log on as a service” privileges.

You must use processManagement.windowsService.serviceUser in conjunction with the --install option.

processManagement.windowsService.servicePassword

Type: string

The password for <user> for mongos or mongod when running with the --serviceUser option.

You must use processManagement.windowsService.servicePassword in conjunction with the --install option.