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       mongod - MongoDB Server


       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.



       --help, -h
              Returns a basic help and usage text.

              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.)

              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

       --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.  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.

              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.

              New in version 2.4.

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

       --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.

              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

              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.

              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

              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."

              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

       --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.

                                  │ValueSetting                          │
                                  │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.

              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.

              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.

              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

       --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.

              Permits  JSONP  access via an HTTP interface. Consider the security implications of
              allowing this activity before enabling this option.

              Disable authentication. Currently the default. Exists for future compatibility  and

              Disables the HTTP interface.

              Disables the durability journaling. By default, mongod enables journaling in 64-bit
              versions after v2.0.

              Disables the preallocation of data files. This will shorten the start  up  time  in
              some   cases,  but  can  cause  significant  performance  penalties  during  normal

              Disables the scripting engine.

              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

                                  │LevelSetting                          │

                                  │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.

              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.

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

              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.

              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.

              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.

              If you set --syncdelay to 0, MongoDB will not sync the memory mapped files to disk.
              Do not set this value on production systems.

              Returns  diagnostic system information and then exits. The information provides the
              page size, the number of physical pages,  and  the  number  of  available  physical

              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

       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.

              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

       --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.

              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

              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.

              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.

              Configures mongod to run as a replication master.

              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.

              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
              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.

              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.

              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

              /administration/ssl for full documentation of MongoDB's support.

              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

              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.

              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.


       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.


       MongoDB Documentation Project


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