Bug 1791853

Summary: Provide guidance and reference values for MongoDB cache when using WiredTiger engine
Product: Red Hat Satellite Reporter: Andrea Perotti <aperotti>
Component: PulpAssignee: satellite6-bugs <satellite6-bugs>
Status: CLOSED DUPLICATE QA Contact: Lai <ltran>
Severity: urgent Docs Contact:
Priority: high    
Version: 6.6.0CC: ltran, ttereshc
Target Milestone: UnspecifiedKeywords: Triaged
Target Release: Unused   
Hardware: Unspecified   
OS: Unspecified   
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Last Closed: 2021-04-20 09:01:55 UTC Type: Bug
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Bug Blocks: 1399395    

Description Andrea Perotti 2020-01-16 15:47:24 UTC 
Description of problem:

The switch to the wiredTiger Storage Engine, offered has a great performance improvement has brought also a big memory issue: as reported in upstream documentation[0] the engine can consume up to half of all memory for its local cache.

[0] https://docs.mongodb.com/manual/core/wiredtiger/

In the solution is reported how to limit the cache size:

https://access.redhat.com/solutions/4505561

but that value is not tested. Customer are left with no reasonable/tested/reference value.

This situation leave customers with two bad options:
- the risk that OOM killer will stop Mongo in case of resources contention
- the risk to affect performance by choosing an arbitrary value for the cache size


Version-Release number of selected component (if applicable):
Sat 6.5+


Actual results:
No guidance on how to avoid mongo taking possession of a Sat6

Expected results:
Having guidance with documented values according to host numbers or other parameters, in a shape like https://github.com/RedHatSatellite/satellite-support/tree/master/tuning-profiles
Comment 8 Tanya Tereshchenko 2021-04-20 09:01:55 UTC 

*** This bug has been marked as a duplicate of bug 1798668 ***