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Configuration File Options

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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.

The following page describes the configuration options available in MongoDB 2.6. 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 control script, you are already using a configuration file.

File Format

Changed in version 2.6.

The configuration file is in YAML format. For example, the following contains various mongod configuration settings in YAML format:

Note

YAML does not accept tabs; use spaces instead.

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

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 mongod --config and mongos --config to specify the configuration file:

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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:

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mongod -f /etc/mongod.conf

mongos -f /etc/mongos.conf

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

Core Options

systemLog Options

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systemLog:
   verbosity: <int>
   quiet: <boolean>
   traceAllExceptions: <boolean>
   syslogFacility: <string>
   path: <string>
   logAppend: <boolean>
   destination: <string>
   timeStampFormat: <string>
systemLog.verbosity

Type: integer

Increases the amount of internal reporting returned on standard output or in log files. To increase the amount of information reported, increase the number.

systemLog.quiet

Type: boolean

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

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

systemLog.traceAllExceptions

Type: boolean

Prints verbose information for debugging. Used for additional logging in support-related troubleshooting.

systemLog.syslogFacility

Type: string

Default: user

Specifies 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 set systemLog.destination to syslog..

systemLog.path

Type: string

Sends all diagnostic logging information to a log file instead of to standard output or to the host’s syslog system. MongoDB creates the log file at the path you specify.

By default, MongoDB overwrites the log file when the process restarts. To instead append to the log file, set the systemLog.logAppend to true.

systemLog.logAppend

Type: boolean

Default: false

If true, appends new entries to the end of the log file rather than overwriting the content of the log when the mongos or mongod instance restarts.

systemLog.destination

Type: string

Specify either file or syslog. If you specify file you must also specify systemLog.path. If you do not specify systemLog.destination, MongoDB will send 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

processManagement Options

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

Type: boolean

Default: false

Enables 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).

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 processManagement.fork setting. Without a specified processManagement.pidFilePath option, the process creates no PID file.

net Options

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net:
   port: <int>
   bindIp: <string>
   maxIncomingConnections: <int>
   wireObjectCheck: <boolean>
   ipv6: <boolean>
   unixDomainSocket:
      enabled: <boolean>
      pathPrefix: <string>
   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>
      weakCertificateValidation: <boolean>
      allowInvalidCertificates: <boolean>
      disabledProtocols: <string>
      FIPSMode: <boolean>
net.port

Type: integer

Default: 27017

Specifies 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 that sets net.bindIp to 127.0.0.1.

Specifies 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: 1000000

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.

Changed in version 2.6: MongoDB removed the upward limit on the maxIncomingConnections setting.

This is particularly useful for a mongos if you have a client that creates a number of connections but allows them to timeout rather than close the connections. When you set this option, ensure the value is slightly higher than the size of the connection pool or the total number of connections, to prevent erroneous connection spikes from propagating to the members of a sharded cluster.

net.wireObjectCheck

Type: boolean

Default: true

Forces the mongod or mongos instance to validate 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

Enables IPv6 support and allows the mongos or mongod to connect to the MongoDB instance using an IPv6 network. All MongoDB programs and processes disable IPv6 support by default.

net.unixDomainSocket Options

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

Type: boolean

Default: false

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

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. 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.http Options

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

Type: boolean

Default: false

New in version 2.6.

Enables 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

In MongoDB Enterprise, the HTTP Console does not support Kerberos Authentication.

net.http.JSONPEnabled

Type: boolean

Default: false

Permits 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.

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

net.http.RESTInterfaceEnabled

Type: boolean

Default: false

Enables 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.

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

net.ssl Options

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

Type: boolean

Deprecated since version 2.6: Use net.ssl.mode: requireSSL instead.

Enables 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 net.port. By default, net.ssl.sslOnNormalPorts is disabled.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.mode

Type: string

New in version 2.6.

Enables TLS/SSL or mixed TLS/SSL used for all network connections. The argument to the net.ssl.mode option 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.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.PEMKeyFile

Type: string

New in version 2.2.

Specifies 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.

When TLS/SSL is enabled, you must specify net.ssl.PEMKeyFile.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.PEMKeyPassword

Type: string

New in version 2.2.

Specifies the password to de-crypt the certificate-key file (i.e. --sslPEMKeyFile). 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.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.clusterFile

Type: string

New in version 2.6.

Specifies 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 option.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.clusterPassword

Type: string

New in version 2.6.

Specifies 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.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.CAFile

Type: string

New in version 2.4.

Specifies 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.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

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.

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

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.weakCertificateValidation

Type: boolean

New in version 2.4.

Disables the requirement for TLS/SSL certificate validation that --sslCAFile enables. With the net.ssl.weakCertificateValidation 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.weakCertificateValidation enabled, the mongos or mongod will validate the certificate using the root certificate chain specified by --sslCAFile and reject clients with invalid certificates.

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

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.allowInvalidCertificates

Type: boolean

New in version 2.6.4.

Bypasses the validation checks for TLS/SSL certificates on other servers in the cluster and allows the use of invalid certificates. When using the allowInvalidCertificates setting, MongoDB logs as a warning the use of the invalid certificate.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

net.ssl.disabledProtocols

Type: string

New in version 2.6.12.

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.

See also

Disallow Protocols

net.ssl.FIPSMode

Type: boolean

New in version 2.4.

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

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

setParameter Option

setParameter

Specifies MongoDB parameter or parameters described in MongoDB Server Parameters

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

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

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

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setParameter:
   enableLocalhostAuthBypass: false

security Options

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security:
   keyFile: <string>
   clusterAuthMode: <string>
   authorization: <string>
   javascriptEnabled:  <boolean>
   sasl:
      hostName: <string>
      serviceName: <string>
      saslauthdSocketPath: <string>
security.keyFile

Type: string

Specifies 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 Authentication Between MongoDB Instances 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.

The default distribution of MongoDB does not contain support for TLS/SSL. For more information on MongoDB and TLS/SSL, see Configure mongod and mongos for TLS/SSL.

security.authorization

Type: string

Default: disabled

Enables 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 Authorization for more information.

The security.authorization option 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.

security.sasl Options

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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.

operationProfiling Options

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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 option is available only for mongod.

operationProfiling.mode

Type: string

Default: off

Changes 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 option is available only for mongod.

storage Options

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storage:
   dbPath: <string>
   directoryPerDB: <boolean>
   indexBuildRetry: <boolean>
   preallocDataFiles: <boolean>
   nsSize: <int>
   smallFiles: <boolean>
   syncPeriodSecs: <int>
   repairPath: <string>
   journal:
      enabled: <boolean>
      debugFlags: <int>
      commitIntervalMs: <num>
   quota:
      enforced: <boolean>
      maxFilesPerDB: <int>
storage.dbPath

Type: string

Default: /data/db on Linux and macOS, \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 option is available only for mongod.

storage.directoryPerDB

Type: boolean

Default: false

Stores each database’s files in its own folder in the data directory. When applied to an existing system, the directoryPerDB option alters the storage pattern of the data directory.

Use this option in conjunction with your file system and device configuration so that MongoDB will store data on a number of distinct disk devices to increase write throughput or disk capacity.

Warning

To enable this option for an existing system, migrate the database-specific data files to the new directory structure before enabling directoryPerDB. Database-specific data files begin with the name of an existing database and end with either “ns” or a number. For example, the following data directory includes files for the local and test databases:

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journal
mongod.lock
local.0
local.1
local.ns
test.0
test.1
test.ns

After migration, the data directory would have the following structure:

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journal
mongod.lock
local/local.0
local/local.1
local/local.ns
test/test.0
test/test.1
test/test.ns

The storage.directoryPerDB option is available only for mongod.

storage.indexBuildRetry

Type: boolean

Default: true

Selects 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 option is available only for mongod.

storage.preallocDataFiles

Type: boolean

Default: true

Enables or disables data file preallocation.

Do not disable data file preallocation in production systems. Only use this option for testing and with small data sets where you frequently drop databases.

storage.nsSize

Type: integer

Default: 16

Specifies 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.nsSize option is available only for mongod.

storage.smallFiles

Type: boolean

Default: false

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

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

The storage.smallFiles option is available only for mongod.

storage.syncPeriodSecs

Type: number

Default: 60

Controls how much time 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. 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 option is available only for mongod.

storage.repairPath

Type: string

Default: A _tmp directory within the path specified by the dbPath option.

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

The storage.repairPath option is available only for mongod.

storage.journal Options

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storage:
   journal:
      enabled: <boolean>
      debugFlags: <int>
      commitIntervalMs: <num>
storage.journal.enabled

Type: boolean

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

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

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

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

storage.journal.commitIntervalMs

Type: number

Default: 100 or 30

The maximum amount of time the mongod process allows between journal operations. Values can range from 2 to 300 milliseconds. Lower values increase the durability of the journal, at the expense of disk performance.

The default journal commit interval is 100 milliseconds if a single block device (e.g. physical volume, RAID device, or LVM volume) contains both the journal and the data files.

If the journal is on a different block device than the data files the default journal commit interval is 30 milliseconds.

To force mongod to commit to the journal more frequently, you can specify j:true. When a write operation with j:true is pending, mongod will reduce commitIntervalMs to a third of the set value.

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

storage.quota Options

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storage:
   quota:
      enforced: <boolean>
      maxFilesPerDB: <int>
storage.quota.enforced

Type: Boolean

Default: false

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

The storage.quota.enforced option is available only for mongod.

storage.quota.maxFilesPerDB

Type: integer

Default: 8

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

The storage.quota.maxFilesPerDB option is available only for mongod.

replication Options

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

Type: integer

Specifies a 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 option is available only for mongod.

replication.replSetName

Type: string

Configures replication. Specify a replica set name as an argument to this set. 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 option is available only for mongod.

replication.secondaryIndexPrefetch

Type: string

Default: all

New in version 2.2.

Determines which indexes 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. This option can have one of the following values:

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 option is available only for mongod.

sharding Options

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

Type: string

Selects the role the mongod instance has in the sharded cluster. Set this option 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 option is available only for mongod.

sharding.archiveMovedChunks

Type: boolean

Default: true

New in version 2.4.

Changed in version 2.6: Starting in MongoDB 2.6, the default value for sharding.archiveMovedChunks is true.

When sharding.archiveMovedChunks is true, the mongod instance saves all documents migrated from the shard to the moveChunk directory of the storage.dbPath. MongoDB does not delete data stored in moveChunk.

auditLog Options

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

Type: string

New in version 2.6.

Enables auditing. The auditLog.destination option 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 auditLog.path in the format specified in auditLog.format.

Note

Available only in MongoDB Enterprise.

auditLog.format

Type: string

New in version 2.6.

Specifies 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 auditLog.path.
BSON Output the audit events in BSON binary format to the file specified in auditLog.path.

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.

Specifies 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.

Specifies 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:

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{ <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

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

Type: boolean

Runs SNMP as a subagent. For more information, see Monitor MongoDB With SNMP on Linux.

The snmp.subagent option is available only for mongod.

snmp.master

Type: boolean

Runs SNMP as a master. For more information, see Monitor MongoDB With SNMP on Linux.

The snmp.master option is available only for mongod.

mongos-only Options

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replication:
   localPingThresholdMs: <boolean>

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

Type: integer

Default: 15

Affects the logic that mongos uses when selecting replica set members to pass read operations from clients. Specify a value in milliseconds. 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 Member Selection 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

Specifies the configuration database for the sharded cluster. You must specify either 1 or 3 configuration servers, in a comma separated list. Always use 3 config servers in production environments.

All mongos instances must specify the exact same value for sharding.configDB

If your configuration databases reside in more that one data center, order the hosts so that first config sever in the list is the closest to the majority of your mongos instances.

Warning

Never remove a config server from this setting, even if the config server is not available or offline.

sharding.chunkSize

Type: integer

Default: 64

Determines 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.

This option 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.

Windows Service Options

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

Type: string

Default: MongoDB

Set 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 option.

processManagement.windowsService.displayName

Type: string

Default: MongoDB

Sets the name listed for MongoDB on the Services administrative application.

processManagement.windowsService.description

Type: string

Default: MongoDB Server

Sets the 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

Runs 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 processManagement.windowsService.serviceUser option.

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

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