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¶
- --help, -h
- Returns a basic help and usage text.
- --version
- Returns the version of the mongod daemon.
- --config <filename>, -f <filename>
- Specifies a configuration file, that you can use to specify
runtime-configurations. While the options are equivalent and accessible
via the other command line arguments, the configuration file is the
preferred method for runtime configuration of mongod. See the "
/reference/configuration-options" document for more
information about these options.
- --verbose, -v
- Increases the amount of internal reporting returned on
standard output or in the log file specified by --logpath. Use the
-v form to control the level of verbosity by including the option
multiple times, (e.g. -vvvvv.)
- --quiet
- Runs the mongod instance in a quiet mode that
attempts to limit the amount of output. This option suppresses:
- •
- output from database commands, including
drop, dropIndexes, diagLogging, validate, and
clean.
- •
- replication activity.
- •
- connection accepted events.
- •
- connection closed events.
- --port <port>
- Specifies a TCP port for the mongod to listen for
client connections. By default mongod listens for connections on
port 27017.
UNIX-like systems require root privileges to use ports with numbers lower
than 1024.
- --bind_ip <ip address>
- The IP address that the mongod process will bind to
and listen for connections. By default mongod listens for
connections on the localhost (i.e. 127.0.0.1 address.) You may
attach mongod to any interface; however, if you attach
mongod to a publicly accessible interface ensure that you have
implemented proper authentication and/or firewall restrictions to protect
the integrity of your database.
- --maxConns <number>
- Specifies the maximum number of simultaneous connections
that mongod will accept. This setting will have no effect if it is
higher than your operating system's configured maximum connection tracking
threshold.
- Note
- You cannot set maxConns to a value higher than
20000.
- --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 run-time.
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.
- --logpath <path>
- Specify a path for the log file that will hold 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
- When specified, this option ensures that mongod
appends new entries to the end of the logfile rather than overwriting the
content of the log when the process restarts.
- --syslog
- New in version 2.1.0.
Sends all logging output to the host's syslog system rather than to
standard output or a log file as with --logpath.
- Warning
- You cannot use --syslog with --logpath.
- --pidfilepath <path>
- Specify a file location to hold the "PID"
or process ID of the mongod process. Useful for tracking the
mongod process in combination with the mongod --fork option.
Without a specified --pidfilepath option, mongos creates no
PID file.
- --keyFile <file>
- Specify the path to a key file to store authentication
information. This option is only useful for the connection between replica
set members.
- See also
-
" Replica Set Security" and "
/administration/replica-sets."
- --nounixsocket
- Disables listening on the UNIX socket. Unless set to false,
mongod and mongos provide a UNIX-socket.
- --unixSocketPrefix <path>
- Specifies a path for the UNIX socket. Unless this option
has a value, mongod and mongos, create a socket with the
/tmp as a prefix.
- --fork
- Enables a daemon mode for mongod that runs
the process to 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 shell. If no
users exist, the localhost interface will continue to have access to the
database until the you create the first user.
See the Security and Authentication page for more information
regarding this functionality.
- --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.
- --dbpath <path>
- Specify a directory for the mongod instance to store
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.
- --diaglog <value>
- 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
--diaglog is for internal use and not intended for most users.
- 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.
- --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.
- --journal
- Enables operation journaling to ensure write durability and
data consistency. mongod enables journaling by default on 64-bit
builds of versions after 2.0.
- --journalOptions <arguments>
- Provides functionality for testing. Not for general use,
and may affect database integrity.
- --journalCommitInterval <value>
- Specifies the maximum amount of time for mongod to
allow between journal operations. The default value is 100 milliseconds,
while possible values range from 2 to 300 milliseconds. Lower values
increase the durability of the journal, at the expense of disk
performance.
To force mongod to commit to the journal more frequently, you can
specify j:true. When a write operation with j:true pending,
mongod will reduce journalCommitInterval to a third of the
set value.
- --ipv6
- Specify this option to enable IPv6 support. This will allow
clients to connect to mongod using IPv6 networks. mongod
disables IPv6 support by default in mongod and all utilities.
- --jsonp
- Permits JSONP access via an HTTP interface. Consider
the security implications of allowing this activity before enabling this
option.
- --noauth
- Disable authentication. Currently the default. Exists for
future compatibility and clarity.
- --nohttpinterface
- Disables the HTTP interface.
- --nojournal
- Disables the durability journaling. By default,
mongod enables journaling in 64-bit versions after v2.0.
- --noprealloc
- Disables the preallocation of data files. This will shorten
the start up time in some cases, but can cause significant performance
penalties during normal operations.
- --noscripting
- Disables the scripting engine.
- --notablescan
- Forbids operations that require a table scan.
- --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; this provides for approximately 24,000
namespaces. Each collection, as well as each index, counts as a
namespace.
- --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.
- --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>
- Modify limit on the number of data files per database. This
option requires the --quota setting. The default value for
--quotaFiles is 8.
- --rest
- Enables the simple REST API.
- --repair
- Runs a repair routine on all databases. This is equivalent
to shutting down and running the repairDatabase database command on
all databases.
- Warning
- In general, if you have an intact copy of your data, such
as would exist on a very recent backup or an intact member of a replica
set, do not use repairDatabase or related options like
db.repairDatabase() in the mongo shell or mongod
--repair. Restore from an intact copy of your data.
- Note
- 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 will refuse to start. In these cases you should start
mongod without the
--repair option to allow
mongod to
recover data from the journal. This will complete more quickly and will result
in a more consistent and complete data set.
To continue the repair operation despite the journal files, shut down
mongod cleanly and restart with the
--repair option.
- Note
- --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.
- --setParameter <options>
- New in version 2.4.
Specifies an option to configure on startup. Specify multiple options with
multiple --setParameter options. See /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
- •
- traceExceptions
- --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.
- --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.
- --shutdown
- Used in control scripts, the --shutdown will
cleanly and safely terminate 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.
--shutdown is only available on Linux systems.
- --syncdelay <value>
- mongod writes data very quickly to the journal, and
lazily to the data files. --syncdelay controls how much time can
pass before MongoDB flushes data to the database files via an
fsync operation. The default setting is 60 seconds. In almost every
situation you should not set this value and use the default setting.
The serverStatus command reports the background flush thread's status
via the backgroundFlushing field.
syncdelay has no effect on the journal files or
journaling.
- Warning
- If you set --syncdelay to 0, MongoDB will not
sync the memory mapped files to disk. Do not set this value on production
systems.
- --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.
- --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.
- Note
- 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.
- --traceExceptions
- For internal diagnostic use only.
Replication Options¶
- --replSet <setname>
- Use this option to configure replication with replica sets.
Specify a setname as an argument to this set. All hosts must have the same
set name.
- See also
-
" /replication," "
/administration/replica-sets," and "
/reference/replica-configuration"
- --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.
- --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.
- 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.
- --replIndexPrefetch
- New in version 2.2.
You must use --replIndexPrefetch in conjunction with replSet.
The default value is all and available options are:
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, the
--autoresync option allows this slave to automatically resync if
the local data is more than 10 seconds behind the master. This option may
be problematic if the oplog is too small (controlled by the
--oplogSize option.) If the oplog not large enough to store
the difference in changes between the master's current state and the state
of the slave, this node will forcibly resync itself unnecessarily. When
you set the If the --autoresync option the slave will not attempt
an automatic resync more than once in a ten minute period.
Sharding 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 mongod with
this option is 27019 and mongod writes all data files to the
/configdb sub-directory of the --dbpath directory.
- --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.
- --noMoveParanoia
- Disables a "paranoid mode" for data writes for
chunk migration operation. See the chunk migration and
moveChunk command documentation for more information.
By default mongod will save copies of migrated chunks on the
"from" server during migrations as "paranoid mode."
Setting this option disables this paranoia.
SSL Options¶
- See
-
/administration/ssl for full documentation of MongoDB's
support.
- --sslOnNormalPorts
- New in version 2.2.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
Enables SSL for
mongod. With
--sslOnNormalPorts, a
mongod
requires SSL encryption for all connections on the default MongoDB port, or
the port specified by
--port. By default,
--sslOnNormalPorts is
disabled.
- --sslPEMKeyFile <filename>
- New in version 2.2.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
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
When using
--sslOnNormalPorts, you must specify
--sslPEMKeyFile.
- --sslPEMKeyPassword <value>
- New in version 2.2.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
Specifies the password to de-crypt the certificate-key file (i.e.
--sslPEMKeyFile). Only use
--sslPEMKeyPassword if the
certificate-key file is encrypted. In all cases,
mongod will redact the
password from all logging and reporting output.
Changed in version 2.4:
--sslPEMKeyPassword is only needed when the
private key is encrypted. In earlier versions
mongod would require
--sslPEMKeyPassword whenever using
--sslOnNormalPorts, even when
the private key was not encrypted.
- --sslCAFile <filename>
- New in version 2.4.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
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
- --sslCRLFile <filename>
- New in version 2.4.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
Specifies the
.pem file that contains the Certificate Revocation List.
Specify the file name of the
.pem file using relative or absolute paths
- --sslWeakCertificateValidation
- New in version 2.4.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
Disables the requirement for SSL certificate validation, that
--sslCAFile
enables. With
--sslWeakCertificateValidation,
mongod will accept
connections if 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.
- --sslFIPSMode
- New in version 2.4.
- Note
- The default distribution of MongoDB does not
contain support for SSL. To use SSL you can either compile MongoDB with
SSL support or use the MongoDB Subscriber Edition. See
/administration/ssl for more information about SSL and
MongoDB.
When specified,
mongod will use the FIPS mode of the installed OpenSSL
library. Your system must have a FIPS compliant OpenSSL library to use
--sslFIPSMode.
USAGE¶
In common usage, the invocation of
mongod will resemble the following in
the context of an initialization or control script:
mongod --config /etc/mongodb.conf
See the "
/reference/configuration-options" for more
information on how to configure
mongod using the configuration file.
AUTHOR¶
MongoDB Documentation Project
COPYRIGHT¶
2011-2013, 10gen, Inc.