NAME

mongod - MongoDB Server

SYNOPSIS

mongod is the primary daemon process for the MongoDB system. It handles data requests, manages data format, and performs background management operations.

This document provides a complete overview of all command line options for mongod. These options are primarily useful for testing purposes. In common operation, use the configuration file options to control the behavior of your database, which is fully capable of all operations described below.

OPTIONS

Core Options

mongod
--help, -h
Returns information on mongod options and usage.
--version
Returns the mongod release number.
--config <filename>, -f
Specifies a configuration file for runtime configuration options. The configuration file is the preferred method for runtime configuration of mongod. The options are equivalent to the command-line configuration options. See http://docs.mongodb.org/manual/reference/configuration-options for more information.

Ensure the configuration file uses ASCII encoding. mongod does not support configuration files with non-ASCII encoding, including UTF-8.

--verbose, -v
Increases the amount of internal reporting returned on standard output or in log files. Increase the verbosity with the -v form by including the option multiple times, (e.g. -vvvvv.)
--quiet
Runs mongod in a quiet mode that attempts to limit the amount of output. This option suppresses:
output from database commands
replication activity
connection accepted events
connection closed events
--port <port>
Specifies the port number when the MongoDB instance is not running on the standard port of 27017. You may also specify the port number using the --host option.
--bind_ip <ip address>
Specifies the IP address that the mongod process binds to and listens for connections on. By default mongod listens for connections for all interfaces. You may attach mongod to any interface. When attaching mongod to a publicly accessible interface, ensure that you have implemented proper authentication and firewall restrictions to protect the integrity of your database.
--maxConns <number>
Specifies the maximum number of simultaneous connections that 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 maxConns setting.

--syslog
Sends all logging output to the host's syslog system rather than to standard output or a log file as with --logpath.

--syslog is not supported on Windows.

--syslogFacility <string>
Specifies the facility level used when logging messages to syslog. The default is user. 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.
--logpath <path>
Specifies the path for the log file that holds all diagnostic logging information.

Unless specified, mongod will output all log information to the standard output. Additionally, unless you also specify --logappend, the logfile will be overwritten when the process restarts.

NOTE: The behavior of the logging system may change in the near future in response to the SERVER-4499 case.

--logappend
Appends new entries to the end of the logfile when the mongod restarts instead of overwriting the content of the log.
--timeStampFormat <string>
Specifies 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 Default value. 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

--diaglog <value>
Deprecated since version 2.6.

--diaglog is for internal use and not intended for most users.

Creates a very verbose, diagnostic log for troubleshooting and recording various errors. MongoDB writes these log files in the dbpath directory in a series of files that begin with the string diaglog and end with the initiation time of the logging as a hex string.

The specified value configures the level of verbosity. Possible values, and their impact are as follows.


Value Setting

0 off. No logging.

1 Log write operations.

2 Log read operations.

3 Log both read and write operations.

7 Log write and some read operations.

You can use the mongosniff tool to replay this output for investigation. Given a typical diaglog file, located at /data/db/diaglog.4f76a58c, you might use a command in the following form to read these files:

mongosniff --source DIAGLOG /data/db/diaglog.4f76a58c

WARNING: Setting the diagnostic level to 0 will cause mongod to stop writing data to the diagnostic log file. However, the mongod instance will continue to keep the file open, even if it is no longer writing data to the file. If you want to rename, move, or delete the diagnostic log you must cleanly shut down the mongod instance before doing so.

--traceExceptions
For internal diagnostic use only.
--pidfilepath <path>
Specifies a file location to hold the "PID" or process ID of the mongod process. Useful for tracking the mongod process in combination with the --fork option.

Without a specified --pidfilepath option, mongod creates no PID file.

--keyFile <file>
Specifies the path to a key file to store authentication information. This option is used for interprocess authentication among the mongos and mongod instances of a sharded cluster or replica set.
--setParameter <options>
New in version 2.4.

Specifies an option to configure on startup. Specify multiple options with multiple --setParameter options. See http://docs.mongodb.org/manual/reference/parameters for full documentation of these parameters. The setParameter database command provides access to many of these parameters. --setParameter supports the following options:

enableLocalhostAuthBypass
enableTestCommands
journalCommitInterval
logLevel
logUserIds
notablescan
quiet
replApplyBatchSize
replIndexPrefetch
supportCompatibilityFormPrivilegeDocuments
syncdelay
textSearchEnabled
traceExceptions
saslauthdPath
authenticationMechanisms
sslMode
clusterAuthMode
--httpinterface
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 security-firewalls.

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

--nohttpinterface
Deprecated since version 2.6: MongoDB disables the HTTP interface by default.

Disables the HTTP interface.

Do not use in conjunction with --rest or --jsonp.

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

--clusterAuthMode <option>
New in version 2.6.

Enables internal x.509 authentication for membership to the cluster or replica set. The --clusterAuthMode option can have one of the following values:


Value Description

keyFile Default value. Use keyfile for authentication.

sendKeyFile For rolling upgrade purposes. Send the keyfile for authentication but can accept either keyfile or x.509 certificate.

sendX509 For rolling upgrade purposes. Send the x.509 certificate for authentication but can accept either keyfile or x.509 certificate.

x509 Recommended. Send the x.509 certificate for authentication and accept only x.509 certificate.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--nounixsocket
Disables listening on the UNIX socket. mongod always listens on the UNIX socket, unless either: --nounixsocket is set, bind_ip is not set, or bind_ip does not specify 127.0.0.1.

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

--unixSocketPrefix <path>
Specifies a path for the UNIX socket. If this option has no value, mongod creates a socket with /tmp as a prefix.

MongoDB will always create and listen on a UNIX socket, unless --nounixsocket is set, bind_ip is not set, or bind_ip does not specify 127.0.0.1.

--fork
Enables a daemon mode for mongod that runs the process in the background. This is the normal mode of operation in production and production-like environments but may not be desirable for testing.
--auth
Enables database authentication for users connecting from remote hosts. Configure users via the mongo shell. If no users exist, the localhost interface will continue to have access to the database until the you create the first user.

See Security and Authentication for more information.

--noauth
Disables authentication. Currently the default. Exists for future compatibility and clarity.
--ipv6
Enables IPv6 support, which allows mongod to connect to the MongoDB instance using an IPv6 network. All MongoDB programs and processes, including mongod, disable IPv6 support by default.
--jsonp
Permits JSONP access via an HTTP interface. Consider the security implications of allowing this activity before enabling this option. If the HTTP interface is disabled, the --jsonp also enables the HTTP interface.

SEE ALSO: --httpinterface

--rest
Enables the simple REST API. Consider the security implications of allowing this activity before enabling this option.

If the HTTP interface is disabled, the --rest setting also enables the HTTP interface.

SEE ALSO: --httpinterface to enable the HTTP interface.

--slowms <value>
Defines the value of "slow," for the --profile option. The database logs all slow queries to the log, even when the profiler is not turned on. When the database profiler is on, mongod the profiler writes to the system.profile collection. See the profile command for more information on the database profiler.
--profile <level>
Changes the level of database profiling, which inserts information about operation performance into output of mongod or the log file. The following levels are available:

Level Setting

0 Off. No profiling.

1 On. Only includes slow operations.

2 On. Includes all operations.

Profiling is off by default. Database profiling can impact database performance. Enable this option only after careful consideration.

--cpu
Forces mongod to report the percentage of CPU time in write lock. mongod generates output every four seconds. MongoDB writes this data to standard output or the logfile if using the logpath option.
--sysinfo
Returns diagnostic system information and then exits. The information provides the page size, the number of physical pages, and the number of available physical pages.
--dbpath <path>
Specifies the directory where the mongod instance stores its data. Typical locations include: /srv/mongodb, /var/lib/mongodb or /opt/mongodb

Unless specified, mongod will look for data files in the default /data/db directory. (Windows systems use the \data\db directory.) If you installed using a package management system. Check the /etc/mongodb.conf file provided by your packages to see the configuration of the --dbpath.

--directoryperdb
Alters the storage pattern of the data directory to store each database's files in a distinct folder. This option will create directories within the --dbpath named for each 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: If you have an existing mongod instance and dbpath, and you want to enable --directoryperdb, you must migrate your existing databases to directories before setting --directoryperdb to access those databases.

Example

Given a dbpath directory with the following items:

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

To enable --directoryperdb you would need to modify the dbpath to resemble the following:

journal
mongod.lock
local/local.0
local/local.1
local/local.ns
test/test.0
test/test.1
test/test.ns
--noIndexBuildRetry
Stops mongod from rebuilding indexes on the next start-up after the program had shut down or stopped in the middle of an index build.
--noprealloc
Disables the preallocation of data files. This shortens the start up time in some cases and can cause significant performance penalties during normal operations.
--nssize <value>
Specifies the default size for namespace files (i.e .ns). This option has no impact on the size of existing namespace files. The maximum size is 2047 megabytes.

The default value is 16 megabytes, which provides for approximately 24,000 namespaces. Each collection, as well as each index, counts as a namespace.

--quota
Enables a maximum limit for the number data files each database can have. When running with --quota, there are a maximum of 8 data files per database. Adjust the quota with the --quotaFiles option.
--quotaFiles <number>
Modifies the limit on the number of data files per database. This option requires the --quota setting. The default value for --quotaFiles is 8.
--smallfiles
Enables a mode where MongoDB uses a smaller default file size. Specifically, --smallfiles reduces the initial size for data files and limits them to 512 megabytes. --smallfiles also reduces the size of each journal files from 1 gigabyte to 128 megabytes.

Use --smallfiles if you have a large number of databases that each holds a small quantity of data. --smallfiles can lead your mongod to create a large number of files, which may affect performance for larger databases.

--syncdelay <value>
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 not set this value and use the default setting.

WARNING: If you set --syncdelay to 0, MongoDB will not sync the memory mapped files to disk.

mongod writes data very quickly to the journal and lazily to the data files. The default syncdelay setting is 60 seconds. syncdelay has no effect on the journal files or journaling.

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

--upgrade
Upgrades the on-disk data format of the files specified by the --dbpath to the latest version, if needed.

This option only affects the operation of mongod if the data files are in an old format.

In most cases you should not set this value, so you can exercise the most control over your upgrade process. See the MongoDB release notes (on the download page) for more information about the upgrade process.

--repair
Runs a repair routine on all databases. This is equivalent to shutting down and running the repairDatabase database command on all databases.

WARNING: During normal operations, only use the repairDatabase command and wrappers including db.repairDatabase() in the mongo shell and mongod --repair, to compact database files and/or reclaim disk space. Be aware that these operations remove and do not save any corrupt data during the repair process.

If you are trying to repair a replica set member, and you have access to an intact copy of your data (e.g. a recent backup or an intact member of the replica set), you should restore from that intact copy, and not use repairDatabase.

When using journaling, there is almost never any need to run repairDatabase. In the event of an unclean shutdown, the server will be able restore the data files to a pristine state automatically.

Changed in version 2.1.2.

If you run the repair option and have data in a journal file, mongod refuses to start. In these cases you should start mongod without the --repair option to allow mongod to recover data from the journal. This completes more quickly and is more likely to produce valid data files. To continue the repair operation despite the journal files, shut down mongod cleanly and restart with the --repair option.

--repair copies data from the source data files into new data files in the repairpath, and then replaces the original data files with the repaired data files. If repairpath is on the same device as dbpath, you may interrupt a mongod running --repair without affecting the integrity of the data set.

--repairpath <path>
Specifies the root directory containing MongoDB data files to use for the --repair operation. Defaults to a _tmp directory within the dbpath.
--objcheck
Forces the mongod to validate all requests from clients upon receipt to ensure that clients never insert invalid documents into the database. For objects with a high degree of sub-document nesting, --objcheck can have a small impact on performance. You can set --noobjcheck to disable object checking at runtime.

Changed in version 2.4: MongoDB enables --objcheck by default, to prevent any client from inserting malformed or invalid BSON into a MongoDB database.

--noobjcheck
New in version 2.4.

Disables the default document validation that MongoDB performs on all incoming BSON documents.

--noscripting
Disables the scripting engine.
--notablescan
Forbids operations that require a table scan.
--journal
Enables operation journaling to ensure write durability and data file validity. mongod enables journaling by default on 64-bit builds of versions after 2.0.
--nojournal
Disables the durability journaling. By default, mongod enables journaling in 64-bit versions after v2.0.
--journalOptions <arguments>
Provides functionality for testing. Not for general use, and will affect data file integrity in the case of abnormal system shutdown.
--journalCommitInterval <value>
Specifies the maximum amount of time for mongod to allow between journal operations. Possible values are between 2 and 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 journalCommitInterval to a third of the set value.

--shutdown
Used in control scripts, the --shutdown cleanly and safely terminates the mongod process. When invoking mongod with this option you must set the --dbpath option either directly or by way of the configuration file and the --config option.

The --shutdown option is available only on Linux systems.

Replication Options

--replSet <setname>
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.

IMPORTANT: 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.

--oplogSize <value>
Specifies a maximum size in megabytes for the replication operation log (e.g. oplog.) By mongod creates an oplog based on the maximum amount of space available. For 64-bit systems, the op log is typically 5% of available disk space. Once the mongod has created the oplog for the first time, changing --oplogSize will not affect the size of the oplog.
--replIndexPrefetch
New in version 2.2.

You must use --replIndexPrefetch in conjunction with replSet. The default value is all and available options are:

none
all
_id_only

By default secondary members of a replica set will load all indexes related to an operation into memory before applying operations from the oplog. You can modify this behavior so that the secondaries will only load the _id index. Specify _id_only or none to prevent the mongod from loading any index into memory.

Master-Slave Replication

These options provide access to conventional master-slave database replication. While this functionality remains accessible in MongoDB, replica sets are the preferred configuration for database replication.

--master
Configures mongod to run as a replication master.
--slave
Configures mongod to run as a replication slave.
--source <host><:port>
For use with the --slave option, the --source option designates the server that this instance will replicate.
--only <arg>
For use with the --slave option, the --only option specifies only a single database to replicate.
--slavedelay <value>
For use with the --slave option, the --slavedelay option configures a "delay" in seconds, for this slave to wait to apply operations from the master node.
--autoresync
For use with the --slave option. When set, --autoresync option allows this slave to automatically resync if it is more than 10 seconds behind the master. This setting may be problematic if the --oplogSize specifies a too small oplog.

If the oplog is not large enough to store the difference in changes between the master's current state and the state of the slave, this instance will forcibly resync itself unnecessarily. When you set the autoresync option to false, the slave will not attempt an automatic resync more than once in a ten minute period.

--fastsync
In the context of replica set replication, set this option if you have seeded this member with a snapshot of the dbpath of another member of the set. Otherwise the mongod will attempt to perform an initial sync, as though the member were a new member.

In the context of replica set replication, set this option if you have seeded this member with a snapshot of the dbpath of another member of the set. Otherwise the mongod will attempt to perform an initial sync, as though the member were a new member.

WARNING: If the data is not perfectly synchronized and mongod starts with fastsync, then the secondary or slave will be permanently out of sync with the primary, which may cause significant consistency problems.

Sharded Cluster Options

--configsvr
Declares that this mongod instance serves as the config database of a sharded cluster. When running with this option, clients will not be able to write data to any database other than config and admin. The default port for a mongod with this option is 27019 and the default --dbpath directory is /data/configdb, unless specified.

Changed in version 2.2: --configsvr also sets --smallfiles.

Changed in version 2.4: --configsvr creates a local oplog.

Do not use --configsvr with --replSet or --shardsvr. Config servers cannot be a shard server or part of a replica set.

--shardsvr
Configures this mongod instance as a shard in a partitioned cluster. The default port for these instances is 27018. The only effect of --shardsvr is to change the port number.
--moveParanoia
New in version 2.4.

During chunk migrations, --moveParanoia forces the mongod instances to save all documents migrated from this shard in the moveChunk directory of the dbpath. MongoDB does not delete data from this directory.

Prior to 2.4, --moveParanoia was the default behavior of MongoDB.

SSL Options

See

http://docs.mongodb.org/manual/tutorial/configure-ssl for full documentation of MongoDB's support.

--ssl
New in version 2.6.

Enables connection to a mongod or mongos that has SSL support enabled.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslMode <mode>
New in version 2.6.

Enables SSL or mixed SSL on a port. The argument to the --sslMode option can be one of the following:


Value Description

disabled The server does not use SSL.

allowSSL Connections between servers do not use SSL. For incoming connections, the server accepts both SSL and non-SSL.

preferSSL Connections between servers use SSL. For incoming connections, the server accepts both SSL and non-SSL.

requireSSL The server uses and accepts only SSL encrypted connections.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslPEMKeyFile <filename>
New in version 2.6.

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

This option is required when using the --ssl option to connect to a mongod or mongos that has sslCAFile enabled without sslWeakCertificateValidation.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslPEMKeyPassword <value>
New in version 2.6.

Specifies the password to de-crypt the certificate-key file (i.e. --sslPEMKeyFile). Use --sslPEMKeyPassword only if the certificate-key file is encrypted. In all cases, mongod will redact the password from all logging and reporting output.

If the private key in the PEM file is encrypted and you do not specify --sslPEMKeyPassword, mongod will prompt for a passphrase. See ssl-certificate-password.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslClusterFile <filename>
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.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslClusterPassword <value>
New in version 2.6.

Specifies the password to de-crypt the x.509 certificate-key file specified with --sslClusterFile. Use --sslClusterPassword only if the certificate-key file is encrypted. In all cases, mongod will redact the password from all logging and reporting output.

Changed in version 2.6: If the x.509 key file is encrypted and you do not specify --sslClusterPassword, mongod will prompt for a passphrase. See ssl-certificate-password.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslCAFile <filename>
New in version 2.6.

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 SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslCRLFile <filename>
New in version 2.6.

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 SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslAllowInvalidCertificates
New in version 2.6.

Bypasses the validation checks for server certificates and allows the use of invalid certificates. When using the sslAllowInvalidCertificates setting, MongoDB logs as a warning the use of the invalid certificate.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslWeakCertificateValidation
New in version 2.4.

Disables the requirement for SSL certificate validation that --sslCAFile enables. With --sslWeakCertificateValidation, mongod will accept connections when the client does not present a certificate when establishing the connection.

If the client presents a certificate and mongod has --sslWeakCertificateValidation enabled, mongod will validate the certificate using the root certificate chain specified by --sslCAFile and reject clients with invalid certificates.

Use --sslWeakCertificateValidation if you have a mixed deployment that includes clients that do not or cannot present certificates to mongod.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

--sslFIPSMode
New in version 2.6.

Directs mongod to use the FIPS mode of the installed OpenSSL library. Your system must have a FIPS compliant OpenSSL library to use --sslFIPSMode.

The default distribution of MongoDB does not contain support for SSL. For more information on MongoDB and SSL, see http://docs.mongodb.org/manual/tutorial/configure-ssl.

Audit Options

--auditDestination
Enables auditing. The --auditDestination 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 the 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: The audit system is available only in MongoDB Enterprise.

--auditFormat
Specifies the format of the output file if --auditDestination is file. The --auditFormat 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: The audit system is available only in MongoDB Enterprise.

--auditPath
Specifies the output file for auditing if --auditDestination has value of file. The --auditPath option can take either a full path name or a relative path name.

NOTE: The audit system is available only in MongoDB Enterprise.

--auditFilter
Specifies the filter to limit the types of operations the audit system records. The option takes a document of the form:

{ atype: <expression> }

For authentication operations, the option can also take a document of the form:

{ atype: <expression>, "param.db": <database> }

NOTE: The audit system is available only in MongoDB Enterprise.

AUTHOR

MongoDB Documentation Project

COPYRIGHT

2011-2014, MongoDB, Inc.