OPTIONS

mongostat

Synopsis

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.

See also

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.

mongostat connects to the mongod instance running on the local host interface on TCP port 27017; however, mongostat can connect to any accessible remote mongod instance.

Access Control Requirements

In order to connect to a mongod that enforces authorization with the --auth option, specify the --username and --password options. The specified user must have sufficient credentials to run the:dbcommand:serverStatus command, which is the clusterAdmin role.

Options

mongostat
mongostat
--help

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.)

--version

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:

<replica_set_name>/<hostname1><:port>,<hostname2:<port>,...
--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.

--ipv6

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.

--ssl

New in version 2.4: MongoDB added support for SSL connections to mongod instances in mongostat.

Note

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.

By default, mongostat assumes that the database specified to the --db argument holds the user’s credentials, unless you specify --authenticationDatabase.

See userSource, system.users Privilege Documents and User Privilege Roles in MongoDB for more information about delegated authentication in MongoDB.

--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.

--noheaders

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.)

--http

Configures mongostat to collect data using the HTTP interface rather than a raw database connection.

--discover

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.

--all

Configures mongostat to return all optional fields.

<sleeptime>

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.

Fields

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:

inserts

The number of objects inserted into the database per second. If followed by an asterisk (e.g. *), the datum refers to a replicated operation.

query

The number of query operations per second.

update

The number of update operations per second.

delete

The number of delete operations per second.

getmore

The number of get more (i.e. cursor batch) operations per second.

command

The number of commands per second. On slave and secondary systems, mongostat presents two values separated by a pipe character (e.g. |), in the form of local|replicated commands.

flushes

The number of fsync operations per second.

mapped

The total amount of data mapped in megabytes. This is the total data size at the time of the last mongostat call.

size

The amount of virtual memory in megabytes used by the process at the time of the last mongostat call.

non-mapped

The total amount of virtual memory excluding all mapped memory at the time of the last mongostat call.

res

The amount of resident memory in megabytes used by the process at the time of the last mongostat call.

faults

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.

locked

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.

qr

The length of the queue of clients waiting to read data from the MongoDB instance.

qw

The length of the queue of clients waiting to write data from the MongoDB instance.

ar

The number of active clients performing read operations.

aw

The number of active clients performing write operations.

netIn

The amount of network traffic, in bytes, received by the MongoDB instance.

This includes traffic from mongostat itself.

netOut

The amount of network traffic, in bytes, sent by the MongoDB instance.

This includes traffic from mongostat itself.

conn

The total number of open connections.

set

The name, if applicable, of the replica set.

repl

The replication status of the member.

Value Replication Type
M master
SEC secondary
REC recovering
UNK unknown
SLV slave

Usage

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:

mongostat --discover
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