The mongostat utility provides a quick overview of the status of a currently running mongod or mongos instance. mongostat is functionally similar to the UNIX/Linux file system utility vmstat, but provides data regarding mongod and mongos instances.
For more information about monitoring MongoDB, see Monitoring for MongoDB.
For more background on various other MongoDB status outputs see:
For an additional utility that provides MongoDB metrics see mongotop.
Returns a basic help and usage text.
- --verbose, -v¶
Increases the amount of internal reporting returned on the command line. Increase the verbosity with the -v form by including the option multiple times, (e.g. -vvvvv.)
Returns the version of the mongostat utility.
- --host <hostname><:port>¶
Specifies a resolvable hostname for the mongod from which you want to export data. By default mongostat attempts to connect to a MongoDB instance running on the localhost port number 27017.
Optionally, specify a port number to connect a MongoDB instance running on a port other than 27017.
To connect to a replica set, you can specify the replica set seed name, and a seed list of set members, in the following format:
- --port <port>¶
Specifies the port number, if the MongoDB instance is not running on the standard port. (i.e. 27017) You may also specify a port number using the mongostat --host command.
Enables IPv6 support that allows mongostat to connect to the MongoDB instance using an IPv6 network. All MongoDB programs and processes, including mongostat, disable IPv6 support by default.
New in version 2.4: MongoDB added support for SSL connections to mongod instances in mongostat.
SSL support in mongostat is not compiled into the default distribution of MongoDB. See Connect to MongoDB with SSL for more information on SSL and MongoDB.
Additionally, mongostat does not support connections to mongod instances that require client certificate validation.
Allows mongostat to connect to mongod instance over an SSL connection.
- --username <username>, -u <username>¶
Specifies a username to authenticate to the MongoDB instance, if your database requires authentication. Use in conjunction with the mongostat --password option to supply a password.
- --password <password>, -p <password>¶
Specifies a password to authenticate to the MongoDB instance. Use in conjunction with the mongostat --username option to supply a username.
If you specify a --username, and do do not pass an argument to --password, mongostat will prompt for a password interactively. If you do not specify a password on the command line, --password must be the last argument specified.
- --authenticationDatabase <dbname>¶
New in version 2.4.
Specifies the database that holds the user’s (e.g --username) credentials.
- --authenticationMechanism <name>¶
New in version 2.4.
Specifies the authentication mechanism. By default, the authentication mechanism is MONGODB-CR, which is the MongoDB challenge/response authentication mechanism. In MongoDB Enterprise, mongostat also includes support for GSSAPI to handle Kerberos authentication.
See Deploy MongoDB with Kerberos Authentication for more information about Kerberos authentication.
Disables the output of column or field names.
- --rowcount <number>, -n <number>¶
Controls the number of rows to output. Use in conjunction with the sleeptime argument to control the duration of a mongostat operation.
Unless --rowcount is specified, mongostat will return an infinite number of rows (e.g. value of 0.)
Configures mongostat to collect data using the HTTP interface rather than a raw database connection.
With this option mongostat discovers and reports on statistics from all members of a replica set or sharded cluster. When connected to any member of a replica set, --discover all non-hidden members of the replica set. When connected to a mongos, mongostat will return data from all shards in the cluster. If a replica set provides a shard in the sharded cluster, mongostat will report on non-hidden members of that replica set.
The mongostat --host option is not required but potentially useful in this case.
The final argument is the length of time, in seconds, that mongostat waits in between calls. By default mongostat returns one call every second.
mongostat returns values that reflect the operations over a 1 second period. For values of <sleeptime> greater than 1, mongostat averages data to reflect average operations per second.
mongostat returns values that reflect the operations over a 1 second period. When mongostat <sleeptime> has a value greater than 1, mongostat averages the statistics to reflect average operations per second.
mongostat outputs the following fields:
The number of objects inserted into the database per second. If followed by an asterisk (e.g. *), the datum refers to a replicated operation.
The number of query operations per second.
The number of update operations per second.
The number of delete operations per second.
The number of get more (i.e. cursor batch) operations per second.
The number of fsync operations per second.
The total amount of data mapped in megabytes. This is the total data size at the time of the last mongostat call.
The amount of virtual memory in megabytes used by the process at the time of the last mongostat call.
The total amount of virtual memory excluding all mapped memory at the time of the last mongostat call.
The amount of resident memory in megabytes used by the process at the time of the last mongostat call.
Changed in version 2.1.
The number of page faults per second.
Before version 2.1 this value was only provided for MongoDB instances running on Linux hosts.
The percent of time in a global write lock.
Changed in version 2.2: The locked db field replaces the locked % field to more appropriate data regarding the database specific locks in version 2.2.
- locked db
New in version 2.2.
The percent of time in the per-database context-specific lock. mongostat will report the database that has spent the most time since the last mongostat call with a write lock.
This value represents the amount of time that the listed database spent in a locked state combined with the time that the mongod spent in the global lock. Because of this, and the sampling method, you may see some values greater than 100%.
- idx miss
The percent of index access attempts that required a page fault to load a btree node. This is a sampled value.
The length of the queue of clients waiting to read data from the MongoDB instance.
The length of the queue of clients waiting to write data from the MongoDB instance.
The number of active clients performing read operations.
The number of active clients performing write operations.
The amount of network traffic, in bytes, received by the MongoDB instance.
This includes traffic from mongostat itself.
The amount of network traffic, in bytes, sent by the MongoDB instance.
This includes traffic from mongostat itself.
The total number of open connections.
The name, if applicable, of the replica set.
In the first example, mongostat will return data every second for 20 seconds. mongostat collects data from the mongod instance running on the localhost interface on port 27017. All of the following invocations produce identical behavior:
mongostat --rowcount 20 1 mongostat --rowcount 20 mongostat -n 20 1 mongostat -n 20
In the next example, mongostat returns data every 5 minutes (or 300 seconds) for as long as the program runs. mongostat collects data from the mongod instance running on the localhost interface on port 27017. Both of the following invocations produce identical behavior.
mongostat --rowcount 0 300 mongostat -n 0 300 mongostat 300
In the following example, mongostat returns data every 5 minutes for an hour (12 times.) mongostat collects data from the mongod instance running on the localhost interface on port 27017. Both of the following invocations produce identical behavior.
mongostat --rowcount 12 300 mongostat -n 12 300
In many cases, using the --discover will help provide a more complete snapshot of the state of an entire group of machines. If a mongos process connected to a sharded cluster is running on port 27017 of the local machine, you can use the following form to return statistics from all members of the cluster: