Run-time Database Configuration
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The command line and configuration file interfaces provide MongoDB administrators with a large number of options and settings for controlling the operation of the database system. This document provides an overview of common configurations and examples of best-practice configurations for common use cases.
While both interfaces provide access to the same collection of options and settings, this document primarily uses the configuration file interface.
If you installed MongoDB with a package manager such as
apton Linux or
brewon macOS, or with the MSI installer on Windows, a default configuration file has been provided as part of your installation:PlatformMethodConfiguration FileLinux
/usr/local/etc/mongod.conf(on Intel processors), or
/opt/homebrew/etc/mongod.conf(on Apple Silicon processors)WindowsMSI Installer
If you installed MongoDB via a downloaded
ZIPfile, you will need to create your own configuration file. The basic example configuration is a good place to start.
For package installations of MongoDB on Linux or macOS, an
initialization script which uses this default configuration file is also
provided. This initialization script can be used to start the
mongod on these platforms in the following manner:
On Linux systems that use the systemd init system (the
sudo systemctl start mongod
On Linux systems that use the SystemV init init system (the
sudo service mongod start
On macOS, using the
brew services start firstname.lastname@example.org
If you installed MongoDB using a
ZIP file, you will need
to create your own configuration file. A
basic example configuration can be found later in
this document. Once you have created a configuration file, you can start
a MongoDB instance with this configuration file by using either the
mongod. For example, on Linux:
mongod --config /etc/mongod.conf mongod -f /etc/mongod.conf
Modify the values in the
mongod.conf file on your system to
control the configuration of your database instance.
Configure the Database
Consider the following basic configuration:
processManagement: fork: true net: bindIp: localhost port: 27017 storage: dbPath: /var/lib/mongo systemLog: destination: file path: "/var/log/mongodb/mongod.log" logAppend: true storage: journal: enabled: true
For most standalone servers, this is a sufficient base configuration. It makes several assumptions, but consider the following explanation:
true, which enables a daemon mode for
mongod, which detaches (i.e. "forks") the MongoDB from the current session and allows you to run the database as a conventional server.
localhost, which forces the server to only listen for requests on the localhost IP. Only bind to secure interfaces that the application-level systems can access with access control provided by system network filtering (i.e. "firewall").
27017, which is the default MongoDB port for database instances. MongoDB can bind to any port. You can also filter access based on port using network filtering tools.
UNIX-like systems require superuser privileges to attach processes to ports lower than 1024.
true. This disables all but the most critical entries in output/log file, and is not recommended for production systems. If you do set this option, you can use
setParameterto modify this setting during run time.
/var/lib/mongo, which specifies where MongoDB will store its data files.
If you installed MongoDB on Linux using a package manager, such as
/etc/mongod.conffile provided with your MongoDB installation sets the following default
dbPath, depending on your Linux distro:PlatformPackage ManagerDefault
dbPathRHEL / CentOS and Amazon
/var/lib/mongoUbuntu and Debian
The user account that
mongodruns under will need read and write access to this directory.
/var/log/mongodb/mongod.logwhich is where
mongodwill write its output. If you do not set this value,
mongodwrites all output to standard output (e.g.
true, which ensures that
mongoddoes not overwrite an existing log file following the server start operation.
true, which enables journaling. Journaling ensures single instance write-durability. 64-bit builds of
mongodenable journaling by default. Thus, this setting may be redundant.
Given the default configuration, some of these values may be redundant. However, in many situations explicitly stating the configuration increases overall system intelligibility.
The following configuration options are useful for limiting access to a
net: bindIp: localhost,10.8.0.10,192.168.4.24,/tmp/mongod.sock security: authorization: enabled
This example provides four values to the
localhost, the localhost interface;
10.8.0.10, a private IP address typically used for local networks and VPN interfaces;
192.168.4.24, a private network interface typically used for local networks; and
/tmp/mongod.sock, a Unix domain socket path.
Because production MongoDB instances need to be accessible from multiple database servers, it is important to bind MongoDB to multiple interfaces that are accessible from your application servers. At the same time it's important to limit these interfaces to interfaces controlled and protected at the network layer.
- Setting this option to
trueenables the authorization system within MongoDB. If enabled you will need to log in by connecting over the
localhostinterface for the first time to create user credentials.
Replication and Sharding Configuration
replica set configuration is straightforward, and only
requires that the
replSetName have a value that is consistent
among all members of the set. Consider the following:
replication: replSetName: set0
Use descriptive names for sets. Once configured, use
mongosh to add hosts to the replica set.
To enable authentication for the replica set using
keyfiles , add the following
keyFile option :
security: keyFile: /srv/mongodb/keyfile
keyFile enables authentication and
specifies a keyfile for the replica set member to use when
authenticating to each other.
The Replica Set Security section for information on configuring authentication with replica sets.
The Replication document for more information on replication in MongoDB and replica set configuration in general.
|||Sharded clusters and replica sets can use x.509 for membership verification instead of keyfiles. For details, see x.509.|
mongod instances with different
mongod configurations for the config servers and the shards. The config servers store the cluster's
metadata, while the shards store the data.
To configure the config server
mongod instances, in the
configuration file, specify
configsvr for the
Changed in version 3.4: Starting in version 3.4, MongoDB removes support for mirrored config servers and config servers must be deployed as a replica set.
sharding: clusterRole: configsvr net: bindIp: 10.8.0.12 port: 27001 replication: replSetName: csRS
To deploy config servers as a replica set, the config servers must run
the WiredTiger Storage Engine.
replica set and add members.
To configure the shard
mongod instances, specify
shardsvr for the
sharding.clusterRole setting, and if
running as a replica set, the replica set name:
sharding: clusterRole: shardsvr replication: replSetName: shardA
If running as a replica set,
shard replica set and add members.
For the router (i.e.
mongos), configure at least one
mongos process with the following setting:
sharding: configDB: csRS/10.8.0.12:27001
You can specify additional members of the config server replica set by specifying hostnames and ports in the form of a comma separated list after the replica set name.
The Sharding section of the manual for more information on sharding and cluster configuration.
Run Multiple Database Instances on the Same System
In many cases running multiple instances of
mongod on a
single system is not recommended. On some types of deployments
 and for testing purposes you may need to run more than
mongod on a single system.
In these cases, use a base configuration for each instance, but consider the following configuration values:
storage: dbPath: /var/lib/mongo/db0/ processManagement: pidFilePath: /var/lib/mongo/db0.pid
dbPath value controls the location of the
mongod instance's data directory. Ensure that each database
has a distinct and well labeled data directory. The
pidFilePath controls where
places it's process ID (PID) file. As this tracks the specific
mongod file, it is crucial that file be unique and well
labeled to make it easy to start and stop these processes.
Create additional init scripts and/or adjust your existing MongoDB configuration and init script as needed to control these processes.
||| Single-tenant systems with SSD or other high
performance disks may provide acceptable performance levels for
The following configuration options control various
behaviors for diagnostic purposes:
operationProfiling.modesets the database profiler level. The profiler is not active by default because of the possible impact on the profiler itself on performance. Unless this setting is on, queries are not profiled.
operationProfiling.slowOpThresholdMsconfigures the threshold which determines whether a query is "slow" for the purpose of the logging system and the profiler. The default value is 100 milliseconds. Set to a lower value if the logging system and the database profiler do not return useful results or set to a higher value to only log the longest running queries.
Starting in version 4.2, secondary members of a replica set now log oplog entries that take longer than the slow operation threshold to apply. These slow oplog messages:
Are logged for the secondaries in the
Are logged under the
REPLcomponent with the text
applied op: <oplog entry> took <num>ms.
Do not depend on the log levels (either at the system or component level)
Do not depend on the profiling level.
May be affected by
slowOpSampleRate, depending on your MongoDB version:
In MongoDB 4.2, these slow oplog entries are not affected by the
slowOpSampleRate. MongoDB logs all slow oplog entries regardless of the sample rate.
In MongoDB 4.4 and later, these slow oplog entries are affected by the
The profiler does not capture slow oplog entries.
systemLog.verbositycontrols the amount of logging output that
mongodwrite to the log. Only use this option if you are experiencing an issue that is not reflected in the normal logging level.
Starting in MongoDB 3.0, you can also specify verbosity level for specific components using the
systemLog.component.<name>.verbositysetting. For the available components, see
component verbosity settings.
For more information, see also Database Profiling and MongoDB Performance.