mongostat

macOS Sierra and Go 1.6 Incompatibility

Users running on macOS Sierra require the 3.2.10 or newer versionof mongostat.

Synopsis

The mongostat utility provides a quick overview of thestatus of a currently running mongodor mongosinstance. mongostat is functionally similar to theUNIX/Linux file system utility vmstat, but provides data regardingmongod and mongos instances.

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

Availability

The mongostat tool is part of the MongoDB tools package. Consult theinstallation guide for your platform forinstructions on how to install the tools package as part of yourMongoDB installation.

The tools package is also available from theMongoDB Download Center,either as a separate tools download, or contained within theTGZ or ZIP downloads, depending on platform. On Windows, the MSI installer includes all tools as part of the default installation.

Tip

If downloading the TGZ or ZIP files from the DownloadCenter, you may want to update your PATH environmentvariable to include the directory where you installed these tools.See the installation guidefor your platform for more information.

Required Access

In order to connect to a mongod that enforces authorizationwith the —auth option, specify the—username and —password options, and the connecting user must have theserverStatus privilege action on the cluster resources.

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

Behavior

FIPS

Starting in version 4.2, MongoDB removes the —sslFIPSModeoption for mongostat. mongostatwill use FIPS compliant connections tomongod/mongos if themongod/mongos instances areconfigured to use FIPS mode.

Options

  • mongostat
  • —help
  • Returns information on the options and use of mongostat.
  • —verbose, -v
  • Increases the amount of internal reporting returned on standard outputor in log files. Increase the verbosity with the -v form byincluding the option multiple times, (e.g. -vvvvv.)
  • —version
  • Returns the mongostat release number.
  • —uri=<connectionString>

New in version 3.4.6.

Specify a resolvable URIconnection string (enclose in quotes) to connect to the MongoDB deployment.

  1. --uri="mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]"

For information on the components of the connection string, seethe Connection String URI Format documentation.

Note

For TLS/SSL options, use the command-line options instead of theURI options for TLS/SSL (Available starting in4.2).

Important

The following command-line options cannot be used in conjunctionwith —uri option:

  • —host=<hostname><:port>, -h=<hostname><:port>
  • Default: localhost:27017

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

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

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

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

Note

You cannot specify both —host and —uri.

  • —port=<port>
  • Default: 27017

Specifies the TCP port on which the MongoDB instance listens forclient connections.

Note

You cannot specify both —port and —uri.

  • —ipv6
  • Removed in version 3.0.

Enables IPv6 support and allows mongostat to connect to theMongoDB instance using an IPv6 network. Prior to MongoDB 3.0, youhad to specify —ipv6 to use IPv6. In MongoDB 3.0 and later, IPv6is always enabled.

  • —ssl

New in version 2.6.

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

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslCAFile=<filename>

New in version 2.6.

Specifies the .pem file that contains the root certificate chainfrom the Certificate Authority. Specify the file name of the.pem file using relative or absolute paths.

Starting in version 3.4, if —tlsCAFile/net.tls.CAFile (ortheir aliases —sslCAFile/net.ssl.CAFile) is not specifiedand you are not using x.509 authentication, the system-wide CAcertificate store will be used when connecting to an TLS/SSL-enabledserver.

To use x.509 authentication, —tlsCAFile or net.tls.CAFilemust be specified unless using —tlsCertificateSelector or—net.tls.certificateSelector. Or if using the ssl aliases,—sslCAFile or net.ssl.CAFile must be specified unless using—sslCertificateSelector or net.ssl.certificateSelector.

Warning

Version 3.2 and earlier: For TLS/SSL connections (—ssl) tomongod and mongos, if the mongostat runs without the—sslCAFile, mongostat will not attemptto validate the server certificates. This creates a vulnerabilityto expired mongod and mongos certificates aswell as to foreign processes posing as valid mongod ormongos instances. Ensure that you always specify theCA file to validate the server certificates in cases whereintrusion is a possibility.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslPEMKeyFile=<filename>

New in version 2.6.

Specifies the .pem file that contains both the TLS/SSL certificateand key. Specify the file name of the .pem file using relativeor absolute paths.

This option is required when using the —ssl option to connectto a mongod or mongos that hasCAFile enabled withoutallowConnectionsWithoutCertificates.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslPEMKeyPassword=<value>

New in version 2.6.

Specifies the password to de-crypt the certificate-key file (i.e.—sslPEMKeyFile). Use the—sslPEMKeyPassword optiononly if the certificate-key file is encrypted. In all cases, themongostat will redact the password from all logging andreporting output.

If the private key in the PEM file is encrypted and you do notspecify the —sslPEMKeyPassword option, the mongostat will promptfor a passphrase. See TLS/SSL Certificate Passphrase.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslCRLFile=<filename>

New in version 2.6.

Specifies the .pem file that contains the Certificate RevocationList. Specify the file name of the .pem file using relative orabsolute paths.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslAllowInvalidCertificates

New in version 2.6.

Bypasses the validation checks for server certificates and allowsthe use of invalid certificates. When using theallowInvalidCertificates setting, MongoDB logs as awarning the use of the invalid certificate.

Starting in MongoDB 4.0, if you specify—sslAllowInvalidCertificates ornet.ssl.allowInvalidCertificates: true (or in MongoDB 4.2, thealias —tlsAllowInvalidateCertificates ornet.tls.allowInvalidCertificates: true) when using x.509authentication, an invalid certificate is only sufficient toestablish a TLS/SSL connection but is insufficient forauthentication.

Warning

Although available, avoid using the—sslAllowInvalidCertificates option if possible. If the use of—sslAllowInvalidCertificates is necessary, only use the optionon systems where intrusion is not possible.

If the mongo shell (and otherMongoDB Tools) runs with the—sslAllowInvalidCertificates option, themongo shell (and otherMongoDB Tools) will not attempt to validatethe server certificates. This creates a vulnerability to expiredmongod and mongos certificates aswell as to foreign processes posing as validmongod or mongos instances. If youonly need to disable the validation of the hostname in theTLS/SSL certificates, see —sslAllowInvalidHostnames.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —sslAllowInvalidHostnames

New in version 3.0.

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

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

  • —username=<username>, -u=<username>
  • Specifies a username with which to authenticate to a MongoDBdatabase that uses authentication. Use in conjunction with the—password and—authenticationDatabase options.

Note

You cannot specify both —username and —uri.

  • —password=<password>, -p=<password>
  • Specifies a password with which to authenticate to a MongoDBdatabase that uses authentication. Use in conjunction with the—username and—authenticationDatabase options.

Changed in version 3.0.2: To prompt the user for the password, pass the —username option without —password orspecify an empty string as the —password value, as in—password="" .

Note

You cannot specify both —password and —uri.

Note

You cannot specify both —authenticationDatabase and —uri.

—authenticationDatabase is required for mongodand mongos instances that use Authentication.

  • —authenticationMechanism=<name>
  • Default: SCRAM-SHA-1

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

Changed in version 4.0: MongoDB removes support for the deprecated MongoDBChallenge-Response (MONGODB-CR) authentication mechanism.

MongoDB adds support for SCRAM mechanism using the SHA-256 hashfunction (SCRAM-SHA-256).

ValueDescriptionSCRAM-SHA-1RFC 5802 standardSalted Challenge Response Authentication Mechanism using the SHA-1hash function.SCRAM-SHA-256RFC 7677 standardSalted Challenge Response Authentication Mechanism using the SHA-256hash function.

Requires featureCompatibilityVersion set to 4.0.

New in version 4.0.

MONGODB-X509MongoDB TLS/SSL certificate authentication.GSSAPI (Kerberos)External authentication using Kerberos. This mechanism isavailable only in MongoDB Enterprise.PLAIN (LDAP SASL)External authentication using LDAP. You can also use PLAINfor authenticating in-database users. PLAIN transmitspasswords in plain text. This mechanism is available only inMongoDB Enterprise.

Note

You cannot specify both —authenticationMechanism and —uri.

  • —gssapiServiceName=<string>

New in version 2.6.

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

This option is available only in MongoDB Enterprise.

  • —gssapiHostName=<string>

New in version 2.6.

Specify the hostname of a service using GSSAPI/Kerberos. Only required if the hostname of a machine doesnot 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 foreasier reading, as in the following sample output:

  1. insert query update delete getmore command dirty used flushes vsize  res qrw arw net_in net_out conn                time
  2.    991    *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
  3.    989    *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
  4.    988    *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
  5.    976    *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 followingsample output:

  1. insert query update delete getmore command dirty used flushes      vsize       res qrw arw   net_in net_out conn                      time
  2.    992    *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
  3.    989    *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
  4.    996    *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
  5.    987    *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 fieldsin the mongostat output.

Use dot notation to specifyserverStatus fields, as inmetrics.document.inserted.

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

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

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

  • rate()
  • Use .rate() to view the rate per second at which aserverStatus field is changing from mongostat call tocall.

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

  • diff()
  • Use .diff() to view how much a serverStatus field haschanged since the previous mongostat call. The intervalbetween calls is specified by <sleeptime>.

View Field Changes with .diff() illustrates how to usemongostat 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 specifiedserverStatus fields after the default mongostat output.

Use dot notation to specifyserverStatus fields, as inmetrics.document.inserted.

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

  1. mongostat -O=host=H,time=T

mongostat supports specifying either-O or -o: you cannot includeboth 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 withthe sleeptime argument to control the duration of amongostat operation.

Unless —rowcount is specified, mongostatwill return an infinite number of rows (e.g. value of 0.)

  • —discover
  • Discovers and reports on statistics from all members of a replicaset or sharded cluster. When connected to any member of areplica set, —discover all non-hidden members of the replica set. When connected to a mongos,mongostat will return data from all shards inthe cluster. If a replica set provides a shard in the sharded cluster,mongostat will report on non-hidden members of that replicaset.

The mongostat —host option is not required butpotentially useful in this case.

Changed in version 2.6: When running with —discover, mongostat nowrespects —rowcount.

  • —http
  • Configures mongostat to collect data using the HTTP interfacerather than a raw database connection.

Changed in version 3.6: MongoDB 3.6 removes the deprecated HTTP interface and REST API toMongoDB.

  • —json

New in version 3.0.0.

Returns output for mongostat in JSON format.

  • —interactive

New in version 3.4.

Display mongostat output in an interactive non-scrolling interfacerather than the default scrolling output.

—interactive is not available with the —jsonoption.

See: View Statistics in an Interactive Interface for an example of —interactive.

  • <sleeptime>
  • Default: 1

The final mongostat argument is the length of time, in seconds, thatmongostat waits in between calls. By default mongostatreturns one call every second.

mongostat returns values that reflect the operationsover a 1 second period. For values of <sleeptime> greaterthan 1, mongostat averages data to reflect averageoperations per second.

Fields

mongostat returns values that reflect the operations over a1 second period. When mongostat <sleeptime> has a valuegreater than 1, mongostat averages the statistics to reflectaverage operations per second.

mongostat outputs the following fields:

  • inserts
  • The number of objects inserted into the database per second. Iffollowed by an asterisk (e.g. *), the datum refers to areplicated 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. Onsecondary systems, mongostat presents two valuesseparated by a pipe character (e.g. |), in the form oflocal|replicated commands.
  • flushes

Changed in version 3.0.

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

  • dirty

New in version 3.0.

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

  • vsize
  • The amount of virtual memory in megabytes used by the process atthe time of the last mongostat call.
  • res
  • The amount of resident memory in megabytes used by the process atthe time of the last mongostat call.
  • locked

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

The percent of time in a global write lock.

  • qr
  • The length of the queue of clients waiting to read data from theMongoDB instance.
  • qw
  • The length of the queue of clients waiting to write data from theMongoDB 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**MmasterSECsecondaryRECrecoveringUNKunknownRTRmongos process (“router”)ARBarbiter

Examples

Specify mongostat Collection Period and Frequency

In the first example, mongostat will return data everysecond for 20 seconds. mongostat collects data from themongod instance running on the localhost interface onport 27017. All of the following invocations produce identicalbehavior:

  1. mongostat --rowcount=20 1
  2. mongostat --rowcount=20
  3. mongostat -n=20 1
  4. mongostat -n=20

In the next example, mongostat returns data every 5 minutes(or 300 seconds) for as long as the program runs. mongostatcollects data from the mongod instance running on thelocalhost interface on port 27017. The followinginvocations produce identical behavior:

  1. mongostat --rowcount=0 300
  2. mongostat -n=0 300
  3. mongostat 300

In the following example, mongostat returns data every 5minutes for an hour (12 times.) mongostat collects datafrom the mongod instance running on the localhost interfaceon port 27017. The following invocations produce identicalbehavior:

  1. mongostat --rowcount=12 300
  2. mongostat -n=12 300

Add Fields to mongostat Output

New in version 3.4.

-O allows you to specify fields fromserverStatus output to add to the defaultmongostat output. The following example adds the hostand version fields as well as the network.numRequests field,which will display as “network requests”, to the defaultmongostat output:

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

The mongostat output would then resemble:

  1. insert query update delete getmore command dirty used flushes vsize   res qrw arw net_in net_out conn                time            host version network requests
  2.     *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
  3.     *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
  4.     *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 itsoutput. You can specify any serverStatus field as amongostat output column. The following example specifies thehost, time, and metrics.document.inserted fields:

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

The mongostat output would then resemble:

  1.            host                time metrics.document.inserted
  2. localhost:37017 Oct 11 12:21:17.370                         0
  3. localhost:37017 Oct 11 12:21:18.371                         0
  4. localhost:37017 Oct 11 12:21:19.371                         0
  5. 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 anumerical field has changed from one mongostat call to thenext. For example, you can view the rate at which documents have beeninserted during an insert operation. .rate() can thereforehelp you view the performance of your mongod instance.

The following example reports on the rate of change of themetrics.document.insertedserverStatus field. Theinvocation uses -o’s ability to specify the name of an columnto label metrics.document.inserted.rate() as “inserted rate” andmetrics.document.inserted as “inserted”:

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

The output would then resemble:

  1.            host mem.bits inserted rate inserted
  2. localhost:37017       64           501     3455
  3. localhost:37017       64           967    13128
  4. localhost:37017       64           972    22851
  5. localhost:37017       64           214    25000
  6. localhost:37017       64             0    25000

View Field Changes with .diff()

New in version 3.4.

.diff() returns the difference between the currentserverStatus field value and the value from the previousmongostat call. The following example returns statistics onthe number of documents being inserted into a collection: inserteddiff is the difference in themetrics.document.inserted field between subsequentcalls, while inserted is the value ofmetrics.document.inserted:

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

The output would then resemble:

  1.            host mem.bits inserted diff inserted
  2. localhost:27017       64             0    25359
  3. localhost:27017       64            94    25453
  4. localhost:27017       64           938    26391
  5. localhost:27017       64           964    27355
  6. localhost:27017       64           978    28333

View Statistics for a Replica Set or Sharded Cluster

In many cases, using the —discover optionwill help provide a more complete snapshot of the state of an entiregroup of machines. If a mongos process connected to asharded cluster is running on port 27017 of the localmachine, you can use the following form to return statistics from allmembers of the cluster:

  1. mongostat --discover

View Statistics in an Interactive Interface

New in version 3.4.

Use the —interactive option toview statistics in a non-scrolling ncurses -styleinteractive output. The —interactive option lets you highlight specifichosts, columns, or fields to view. When combined with —discover,—interactive displays statistics for all members of areplica set or sharded cluster, as in the following example:

  1. mongostat --discover --interactive

The output for a sharded cluster would then resemble:

  1.                   host insert query update delete getmore command dirty used flushes mapped vsize   res faults qrw arw net_in net_out conn set repl                time
  2. hostname.local:27018     *0    *0     *0     *0       0     1|0  0.0% 0.0%       0        3.25G 25.0M    n/a 0|0 1|0   157b   43.9k   19 tic  PRI Nov  2 11:44:46.439
  3. hostname.local:27019     *0    *0     *0     *0       0     2|0  0.0% 0.0%       0        3.18G 26.0M    n/a 0|0 1|0   322b   44.4k   12 tic  SEC Nov  2 11:44:46.439
  4. hostname.local:27020     *0    *0     *0     *0       0     2|0  0.0% 0.0%       0        3.18G 26.0M    n/a 0|0 1|0   322b   44.4k   12 tic  SEC Nov  2 11:44:46.439
  5. hostname.local:27021   2017    *0     *0     *0     826  1029|0  0.0% 0.0%       0        3.25G 31.0M    n/a 0|0 1|0  1.74m   1.60m   20 tac  PRI Nov  2 11:44:46.439
  6. hostname.local:27022  *2021    *0     *0     *0       0     2|0  0.0% 0.0%       0        3.19G 32.0M    n/a 0|0 1|0   322b   44.6k   12 tac  SEC Nov  2 11:44:46.438
  7. hostname.local:27023  *2022    *0     *0     *0       0     3|0  0.0% 0.0%       0        3.19G 33.0M    n/a 0|0 1|0   323b   44.7k   12 tac  SEC Nov  2 11:44:46.438
  8.      localhost:27017   2071    *0     *0     *0       0  2073|0                  0     0B 2.43G 9.00M      0 0|0 0|0   249k    130k    4      RTR Nov  2 11:44:47.429
  9.  
  10. Press '?' to toggle help

Additional Information

For more information about monitoring MongoDB, seeMonitoring for MongoDB.

For more background on other MongoDB status outputs see:

For an additional utility that provides MongoDB metrics seemongotop.