How to Monitor MongoDB

MongoDB provides various metrics through their serverStatus command call. Setting up monitoring for MongoDB with Nixstats is easy, you can read more at our helpdesk.

Important MongoDB Metrics

The most important metrics to watch and alert to for MongoDB are asserts which represent errors. More details about asserts can be found in the mongodb log files, we recommend setting up logging to Nixstats for easy management. You can setup a daily log alert to notify you of any assert errors in your logs.

MongoDB Metrics

The following metrics are available from the MongoDB monitoring plugin. Source code is available on GitHub.

• asserts-msg

  Indicate internal server exceptions. Check the log file for more information about these messages.

• asserts-regular

  Per operation invariants (for example “unexpected failure while reading a BSON document”). Check the log file for more information about these messages.

• asserts-rollovers

  The number of times that the rollover counters have rolled over since the last time the MongoDB process started.

• asserts-user

  Indicates error returned to the client such as a duplicate key exception or write error.

• asserts-warning

  Indicates less serious errors such as a low ulimit. Check the log file for more information about these messages.

• connections-available

  The number of unused incoming connections available.

• connections-current

  The number of incoming connections from clients to the database server .

• connections-totalCreated

  Count of all incoming connections created to the server. This number includes connections that have since closed.

• globalLock-activeClients-readers

  The number of the active client connections performing read operations.

• globalLock-activeClients-total

  The total number of internal client connections to the database including system threads as well as queued readers and writers.

• globalLock-activeClients-writers

  The number of active client connections performing write operations.

• globalLock-currentQueue-total

  The total number of operations queued waiting for the lock.

• globalLock-currentQueue-writers

  The number of operations that are currently queued and waiting for the write lock. A consistently small write-queue, particularly of shorter operations, is no cause for concern.

• globalLock-currentQueue-readers

  The number of operations that are currently queued and waiting for the read lock. A consistently small read-queue, particularly of shorter operations, should cause no concern.

• isprimary

  1 for primary replicaset status, 0 for secondary.

• locks-collection-acquireCount-r

• locks-collection-acquireCount-w

• locks-database-acquireCount-R

• locks-database-acquireCount-W

• locks-database-acquireCount-r

• locks-database-acquireCount-w

• locks-database-acquireWaitCount-W

• locks-database-acquireWaitCount-r

• locks-database-acquireWaitCount-w

• locks-database-timeAcquiringMicros-W

• locks-database-timeAcquiringMicros-r

• locks-database-timeAcquiringMicros-w

• locks-global-acquireCount-W

• locks-global-acquireCount-r

• locks-global-acquireCount-w

• locks-global-acquireWaitCount-W

• locks-global-acquireWaitCount-r

• locks-global-acquireWaitCount-w

• locks-global-timeAcquiringMicros-W

• locks-global-timeAcquiringMicros-r

• locks-global-timeAcquiringMicros-w

• locks-metadata-acquireCount-W

• locks-oplog-acquireCount-W

• locks-oplog-acquireCount-r

• locks-oplog-acquireCount-w

• mem-bits

  Indicates a 64bit or 32bit instance of mongod

• mem-resident

  The value of mem.resident is roughly equivalent to the amount of RAM, in mebibyte (MiB), currently used by the database process.

• mem-supported

• mem-virtual

  Displays the quantity, in mebibyte (MiB), of virtual memory used by the mongod process.

• members

  The amount of members in a replicaset.

• opLatencies-commands-latency

  Query latency for command queries in microseconds.

• opLatencies-commands-ops

  The number of operations performed on the collection.

• opLatencies-reads-latency

  Query latency for read queries in microseconds.

• opLatencies-reads-ops

  The number of operations performed on the collection.

• opLatencies-writes-latency

  Query latency for write queries in microseconds.

• opLatencies-writes-ops

  The number of operations performed on the collection.

• opcounters-command

  The amount of command operations per second.

• opcounters-delete

  The amount of delete operations per second.

• opcounters-getmore

  The amount of getmore operations per second.

• opcounters-insert

  The amount of insert operations per second.

• opcounters-query

  The amount of query operations per second.

• opcounters-update

  The amount of update operations per second.

• opcountersRepl-command

  The number of replicated command operations per second.

• opcountersRepl-delete

  The number of replicated delete operations per second.

• opcountersRepl-getmore

  The number of replicated getmore operations per second.

• opcountersRepl-insert

  The number of replicated insert operations per second.

• opcountersRepl-query

  The number of replicated query operations per second.

• opcountersRepl-update

  The number of replicated update operations per second.

• transactions-retriedCommandsCount

  The total number of retry attempts that have been received after the corresponding retryable write command has already been committed

• transactions-retriedStatementsCount

  The total number of write statements associated with the retried commands in transactions.retriedCommandsCount.

• transactions-transactionsCollectionWriteCount

  The number of writes to the config.transactions collection, triggered when a new retryable write statement is committed.