Mongo DB

omkd Daemon will not start, or starts and fails immediately

If the mongod daemon is not running omkd will never start. Ever.

Use df -h to check for drive space. if available space for the participation the Mongo DB is stored in is <5% the dB will not start. Determine what is taking up space, usually application log file but may also be syslog, snmpTraps, or nfdump files waiting to be processed.

In-memory Sort Operations

If the following repetitive error is observed in /usr/local/omk/log/opEvents.log it may be related to a MongoDB resource issue.

[Sat Nov  3 20:47:51 2018] [error] supervisor[4683] worker process 5424 exited with code 255
[Sat Nov  3 20:47:51 2018] [info] worker process terminated after only 1s, delaying restart for 32s

Look for a corresponding error in mongod.log

2018-11-03T20:47:51.596+0000 E QUERY    [conn507] Plan executor error during find command: FAILURE, stats: { stage: "SORT", nRetu
rned: 0, executionTimeMillisEstimate: 550, works: 459671, advanced: 0, needTime: 459670, needYield: 0, saveState: 3592, restoreSt
ate: 3592, isEOF: 0, invalidates: 0, sortPattern: { time: -1 }, memUsage: 33554492, memLimit: 33554432, inputStage: { stage: "SOR
T_KEY_GENERATOR", nReturned: 0, executionTimeMillisEstimate: 380, works: 459670, advanced: 0, needTime: 2, needYield: 0, saveStat
e: 3592, restoreState: 3592, isEOF: 0, invalidates: 0, inputStage: { stage: "COLLSCAN", filter: { $and: [] }, nReturned: 459668, 
executionTimeMillisEstimate: 90, works: 459669, advanced: 459668, needTime: 1, needYield: 0, saveState: 3592, restoreState: 3592,
 isEOF: 0, invalidates: 0, direction: "forward", docsExamined: 459668 } } }

This MongoDB error is related to an in-memory sort, default memory limit of 32MB as descibed here:

https://docs.mongodb.com/manual/reference/limits/#Sort-Operations

The memory limit for 'in-memory sort' operations may be increased as described here:

https://jira.mongodb.org/browse/SERVER-23768