`mongostat`¶

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Mac OSX Sierra and Go 1.6 Incompatibility

Users running on Mac OSX Sierra require the 3.2.10 or newer version of 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.

Run mongostat from the system command line, not the mongo shell.

Required Access¶

In order to connect to a mongod that enforces authorization with the --auth option, specify the --username and --password options, and the connecting user must have the serverStatus privilege action on the cluster resources.

The built-in role clusterMonitor provides this privilege as well as other privileges. To create a role with just the privilege to run mongostat, see Create a Role to Run mongostat.

Options¶

mongostat¶

mongostat¶

--help¶: Returns information on the options and use of mongostat.

--verbose, -v¶: Increases the amount of internal reporting returned on standard output or in log files. Increase the verbosity with the -v form by including the option multiple times, (e.g. -vvvvv.)

--version¶: Returns the mongostat release number.

--host <hostname><:port>, -h <hostname><:port>¶

Default: localhost:27017

Specifies a resolvable hostname for the mongod to which to connect. By default, the mongostat attempts to connect to a MongoDB instance running on the localhost on port number 27017.

To connect to a replica set, you can specify the set member or members to report on, as in the following (see also the --discover flag):

--host <hostname1><:port>,<hostname2><:port>,<...>

Changed in version 3.0.0: If you use IPv6 and use the <address>:<port> format, you must enclose the portion of an address and port combination in brackets (e.g. [<address>]).

--port <port>¶

Default: 27017

Specifies the TCP port on which the MongoDB instance listens for client connections.

--ipv6¶

Removed in version 3.0.

Enables IPv6 support and allows mongostat to connect to the MongoDB instance using an IPv6 network. Prior to MongoDB 3.0, you had to specify --ipv6 to use IPv6. In MongoDB 3.0 and later, IPv6 is always enabled.

--ssl¶: New in version 2.6.

Enables connection to a mongod or mongos that has TLS/SSL support enabled.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslCAFile <filename>¶: New in version 2.6.

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.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

Warning

Version 3.2 and earlier: For SSL connections (--ssl) to mongod and mongos, if the mongostat runs without the --sslCAFile, mongostat will not attempt to validate the server certificates. This creates a vulnerability to expired mongod and mongos certificates as well as to foreign processes posing as valid mongod or mongos instances. Ensure that you always specify the CA file to validate the server certificates in cases where intrusion is a possibility.

--sslPEMKeyFile <filename>¶

New in version 2.6.

Specifies the .pem file that contains both the TLS/SSL certificate and key. Specify the file name of the .pem file using relative or absolute paths.

This option is required when using the --ssl option to connect to a mongod or mongos that has CAFile enabled without allowConnectionsWithoutCertificates.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslPEMKeyPassword <value>¶

New in version 2.6.

Specifies the password to de-crypt the certificate-key file (i.e. --sslPEMKeyFile). Use the --sslPEMKeyPassword option only if the certificate-key file is encrypted. In all cases, the mongostat will redact the password from all logging and reporting output.

If the private key in the PEM file is encrypted and you do not specify the --sslPEMKeyPassword option, the mongostat will prompt for a passphrase. See SSL Certificate Passphrase.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslCRLFile <filename>¶: New in version 2.6.

Specifies the .pem file that contains the Certificate Revocation List. Specify the file name of the .pem file using relative or absolute paths.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslAllowInvalidCertificates¶: New in version 2.6.

Bypasses the validation checks for server certificates and allows the use of invalid certificates. When using the allowInvalidCertificates setting, MongoDB logs as a warning the use of the invalid certificate.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslAllowInvalidHostnames¶: New in version 3.0.

Disables the validation of the hostnames in TLS/SSL certificates. Allows mongostat to connect to MongoDB instances even if the hostname in their certificates do not match the specified hostname.

Changed in version 3.0: Most MongoDB distributions include support for TLS/SSL. See Configure mongod and mongos for TLS/SSL and TLS/SSL Configuration for Clients for more information about TLS/SSL and MongoDB.

Changed in version 3.4: If --sslCAFile is not specified when connecting to an TLS/SSL-enabled server, the system-wide CA certificate store will be used.

--sslFIPSMode¶: New in version 2.6.

Directs the mongostat to use the FIPS mode of the installed OpenSSL library. Your system must have a FIPS compliant OpenSSL library to use the --sslFIPSMode option.

Note

FIPS-compatible SSL is available only in MongoDB Enterprise. See Configure MongoDB for FIPS for more information.

--username <username>, -u <username>¶: Specifies a username with which to authenticate to a MongoDB database that uses authentication. Use in conjunction with the --password and --authenticationDatabase options.

--password <password>, -p <password>¶: Specifies a password with which to authenticate to a MongoDB database that uses authentication. Use in conjunction with the --username and --authenticationDatabase options.

Changed in version 3.0.0: If you do not specify an argument for --password, mongostat returns an error.

Changed in version 3.0.2: If you wish mongostat to prompt the user for the password, pass the --username option without --password or specify an empty string as the --password value, as in --password "" .

--authenticationDatabase <dbname>¶

Specifies the database in which the user is created. See Authentication Database.

--authenticationDatabase is required for mongod and mongos instances that use Authentication.

--authenticationMechanism <name>¶

Default: SCRAM-SHA-1

Changed in version 2.6: Added support for the PLAIN and MONGODB-X509 authentication mechanisms.

Changed in version 3.0: Added support for the SCRAM-SHA-1 authentication mechanism. Changed default mechanism to SCRAM-SHA-1.

Specifies the authentication mechanism the mongostat instance uses to authenticate to the mongod or mongos.

Value	Description
SCRAM-SHA-1	RFC 5802 standard Salted Challenge Response Authentication Mechanism using the SHA1 hash function.
MONGODB-CR	MongoDB challenge/response authentication.
MONGODB-X509	MongoDB TLS/SSL certificate authentication.
GSSAPI (Kerberos)	External authentication using Kerberos. This mechanism is available only in MongoDB Enterprise.
PLAIN (LDAP SASL)	External authentication using LDAP. You can also use `PLAIN` for authenticating in-database users. `PLAIN` transmits passwords in plain text. This mechanism is available only in MongoDB Enterprise.

--gssapiServiceName¶

New in version 2.6.

Specify the name of the service using GSSAPI/Kerberos. Only required if the service does not use the default name of mongodb.

This option is available only in MongoDB Enterprise.

--gssapiHostName¶

New in version 2.6.

Specify the hostname of a service using GSSAPI/Kerberos. Only required if the hostname of a machine does not match the hostname resolved by DNS.

This option is available only in MongoDB Enterprise.

--humanReadable boolean¶

Default: True

New in version 3.4.

When true, mongostat formats dates and quantity values for easier reading, as in the following sample output:

insert query update delete getmore command dirty used flushes vsize  res qrw arw net_in net_out conn                time
  *0     *0     *0       0     2|0  3.4% 4.5%       0 2.90G 297M 0|0 0|0  12.9m   84.2k    2 Oct  6 09:45:37.478
  *0     *0     *0       0     2|0  3.6% 4.7%       0 2.91G 310M 0|0 0|0  12.9m   84.1k    2 Oct  6 09:45:38.476
  *0     *0     *0       0     1|0  3.7% 4.8%       0 2.92G 323M 0|0 0|0  12.8m   83.8k    2 Oct  6 09:45:39.481
  *0     *0     *0       0     2|0  3.9% 5.0%       0 2.94G 335M 0|0 0|0  12.7m   83.7k    2 Oct  6 09:45:40.476

When false, mongostat returns the raw data, as in the following sample output:

insert query update delete getmore command dirty used flushes      vsize       res qrw arw   net_in net_out conn                      time
  *0     *0     *0       0     2|0   1.3  2.4       0 2941255680 149946368 0|0 0|0 12913607   84271    2 2016-10-06T09:45:25-04:00
  *0     *0     *0       0     1|0   1.5  2.6       0 2974810112 163577856 0|0 0|0 12873225   84087    2 2016-10-06T09:45:26-04:00
  *0     *0     *0       0     1|0   1.6  2.8       0 2972712960 177209344 0|0 0|0 12955423   84345    2 2016-10-06T09:45:27-04:00
  *0     *0     *0       0     1|0   1.8  2.9       0 2989490176 190840832 0|0 0|0 12861852   84008    2 2016-10-06T09:45:28-04:00

-o <field list>¶

New in version 3.4.

When specified, mongostat includes only the specified fields in the mongostat output.

Use dot notation to specify serverStatus fields, as in metrics.document.inserted.

To specify a custom name for a field, use <field>=<customName>, as in:

mongostat -o 'host=H,time=T,version=MongoDB Version'

-o supports the following methods to modify the information returned for a given serverStatus field:

rate()¶

Use rate() to view the rate per second at which a serverStatus field is changing from mongostat call to call.

View Rate of Change for a Field with rate() illustrates how to use mongostat with -o and the rate() method.

diff()¶

Use diff() to view how much a serverStatus field has changed since the previous mongostat call. The interval between calls is specified by <sleeptime>.

View Field Changes with diff() illustrates how to use mongostat with -o and the diff() method.

mongostat supports specifying either -o or -O: you cannot include both options.

See Specify mongostat Output Fields for an example of -o.

-O <field list>¶

New in version 3.4.

When specified, mongostat includes the specified serverStatus fields after the default mongostat output.

Use dot notation to specify serverStatus fields, as in metrics.document.inserted.

To specify a custom name for a field, use <field>=<customName>, as in:

mongostat -O host=H,time=T

mongostat supports specifying either -O or -o: you cannot include both options.

See Add Fields to mongostat Output for an example of -O.

--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.

Deprecated since version 3.2: HTTP interface for MongoDB

--discover¶

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.

Changed in version 2.6: When running with --discover, mongostat now respects --rowcount.

--all¶: Configures mongostat to return all optional fields.

--json¶: New in version 3.0.0.

Returns output for mongostat in JSON format.

<sleeptime>¶

Default: 1

The final mongostat 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

Changed in version 3.0.

For the WiredTiger Storage Engine, flushes refers to the number of WiredTiger checkpoints triggered between each polling interval.

For the MMAPv1 Storage Engine, flushes represents the number of fsync operations per second.

dirty: New in version 3.0.

Only for WiredTiger Storage Engine. The percentage of the WiredTiger cache with dirty bytes, calculated by wiredTiger.cache.tracked dirty bytes in the cache / wiredTiger.cache.maximum bytes configured.

used: New in version 3.0.

Only for WiredTiger Storage Engine. The percentage of the WiredTiger cache that is in use, calculated by wiredTiger.cache.bytes currently in the cache / wiredTiger.cache.maximum bytes configured.

mapped: Changed in version 3.0.

Only for MMAPv1 Storage Engine. The total amount of data mapped in megabytes. This is the total data size at the time of the last mongostat call.

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

non-mapped

Changed in version 3.0.

Only for MMAPv1 Storage Engine.

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

mongostat only returns this value when started with the --all option.

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

faults: Changed in version 3.0.

Only for MMAPv1 Storage Engine. The number of page faults per second.

Changed in version 2.1: Before version 2.1, this value was only provided for MongoDB instances running on Linux hosts.

lr: New in version 3.2.

Only for MMAPv1 Storage Engine. The percentage of read lock acquisitions that had to wait. mongostat displays lr|lw if a lock acquisition waited.

lw: New in version 3.2.

Only for MMAPv1 Storage Engine. The percentage of write lock acquisitions that had to wait. mongostat displays lr|lw if a lock acquisition waited.

lrt: New in version 3.2.

Only for MMAPv1 Storage Engine. The average acquire time, in microseconds, of read lock acquisitions that waited. mongostat displays lrt|lwt if a lock acquisition waited.

lwt: New in version 3.2.

Only for MMAPv1 Storage Engine. The average acquire time, in microseconds, of write lock acquisitions that waited. mongostat displays lrt|lwt if a lock acquisition waited.

locked: Changed in version 3.0: Only appears when mongostat runs against pre-3.0 versions of MongoDB instances.

The percent of time in a global write lock.

idx miss: Changed in version 3.0.

Only for MMAPv1 Storage Engine. 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
RTR	mongos process (“router”)
ARB	arbiter

Use¶

Specify `mongostat` Collection Period and Frequency¶

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. 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. The following invocations produce identical behavior:

mongostat --rowcount 12 300
mongostat -n 12 300

Add Fields to `mongostat` Output¶

New in version 3.4.

-O allows you to specify fields from serverStatus output to add to the default mongostat output. The following example adds the host and version fields as well as the network.numRequests field, which will display as “network requests”, to the default mongostat output:

mongostat -O 'host,version,network.numRequests=network requests'

The mongostat output would then resemble:

insert query update delete getmore command dirty used flushes vsize   res qrw arw net_in net_out conn                time            host version network requests
    *0    *0     *0     *0       0     2|0  0.0% 0.0%       0 2.51G 19.0M 0|0 0|0   158b   39.4k    2 Oct 11 12:14:45.878 localhost:37017  3.3.14               91
    *0    *0     *0     *0       0     1|0  0.0% 0.0%       0 2.51G 19.0M 0|0 0|0   157b   39.3k    2 Oct 11 12:14:46.879 localhost:37017  3.3.14               95
    *0    *0     *0     *0       0     1|0  0.0% 0.0%       0 2.51G 19.0M 0|0 0|0   157b   39.2k    2 Oct 11 12:14:47.884 localhost:37017  3.3.14               99

Specify `mongostat` Output Fields¶

New in version 3.4.

-o specifies the columns mongostat includes in its output. You can specify any serverStatus field as a mongostat output column. The following example specifies the host, time, and metrics.document.inserted fields:

mongostat -o 'host,time,metrics.document.inserted'

The mongostat output would then resemble:

           host                time metrics.document.inserted
localhost:37017 Oct 11 12:21:17.370                         0
localhost:37017 Oct 11 12:21:18.371                         0
localhost:37017 Oct 11 12:21:19.371                         0
localhost:37017 Oct 11 12:21:20.368                         0

View Rate of Change for a Field with `rate()`¶

New in version 3.4.

rate() enables you to view the rate per second at which a numerical field has changed from one mongostat call to the next. For example, you can view the rate at which documents have been inserted during an insert operation. rate() can therefore help you view the performance of your mongod instance.

The following example reports on the rate of change of the metrics.document.inserted serverStatus field. The invocation uses -o’s ability to specify the name of an column to label metrics.document.inserted.rate() as “inserted rate” and metrics.document.inserted as “inserted”:

mongostat -o 'host,mem,bits,metrics.document.inserted.rate()=inserted rate,metrics.document.inserted=inserted' --rowcount 5

The output would then resemble:

           host mem.bits inserted rate inserted
localhost:37017       64           501     3455
localhost:37017       64           967    13128
localhost:37017       64           972    22851
localhost:37017       64           214    25000
localhost:37017       64             0    25000

View Field Changes with `diff()`¶

New in version 3.4.

diff() returns the difference between the current serverStatus field value and the value from the previous mongostat call. The following example returns statistics on the number of documents being inserted into a collection: inserted diff is the difference in the metrics.document.inserted field between subsequent calls, while inserted is the value of metrics.document.inserted:

mongostat -o 'host,mem.bits,metrics.document.inserted.diff()=inserted diff,metrics.document.inserted=inserted' --rowcount 5

The output would then resemble:

           host mem.bits inserted diff inserted
localhost:27017       64             0    25359
localhost:27017       64            94    25453
localhost:27017       64           938    26391
localhost:27017       64           964    27355
localhost:27017       64           978    28333

View Statistics for a Replica Set or Sharded Cluster¶

In many cases, using the --discover option 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

← mongoexport mongotop →

mongostat¶

Synopsis¶

Required Access¶

Options¶

Fields¶

Use¶

Specify mongostat Collection Period and Frequency¶

Add Fields to mongostat Output¶

Specify mongostat Output Fields¶

View Rate of Change for a Field with rate()¶

View Field Changes with diff()¶

View Statistics for a Replica Set or Sharded Cluster¶

`mongostat`¶

Specify `mongostat` Collection Period and Frequency¶

Add Fields to `mongostat` Output¶

Specify `mongostat` Output Fields¶

View Rate of Change for a Field with `rate()`¶

View Field Changes with `diff()`¶