[DOCS-491] Working-set calculation, RAM, oplog, non-mapped memory, and faults Created: 05/Sep/12  Updated: 30/Oct/23  Resolved: 03/Jan/13

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Improvement Priority: Major - P3
Reporter: A. Jesse Jiryu Davis Assignee: Bob Grabar
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Participants:
Days since reply: 11 years, 6 weeks, 4 days ago

 Description   

Based on customer interaction, it seems we need a better doc than this one for calculating how much RAM you need for your app:

http://www.mongodb.org/display/DOCS/Checking+Server+Memory+Usage#CheckingServerMemoryUsage-WorkingSetSize

I think there's some useful verbiage in my responses to CS-4233, and probably scattered all over in a million answers from 10gen staff to questions over the years of the form, "Do I have enough RAM?"

Here are the points I think we should hit:
*) Relationship b/w db storage and working set
*) OS's LRU cache strategy
*) Impact of journaling
*) Using page faults and other MMS gauges to detect when you need more RAM
*) What is non-mapped memory? It's basically a linear function of connection count.
*) The oplog can be ignored when calculating working set (for some reason, that customer thought it was especially important when the opposite is true)



 Comments   
Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2013-01-05T15:17:39Z', u'email': u'samk@10gen.com', u'name': u'Sam Kleinman'}

Message: DOCS-491 editing and organization
Branch: master
https://github.com/mongodb/docs/commit/5395dd089582398f65a891f1f31e137da5e7e190

Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2013-01-05T14:50:37Z', u'email': u'samk@10gen.com', u'name': u'Sam Kleinman'}

Message: merge: DOCS-491
Branch: master
https://github.com/mongodb/docs/commit/c7cd7b7573f6d0ac526fbe7095ecb18bb4df37bd

Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2012-12-21T16:28:38Z', u'email': u'bob.grabar@10gen.com', u'name': u'Bob Grabar'}

Message: DOCS-491 review edits
Branch: master
https://github.com/mongodb/docs/commit/54b54d64d325bd827d93b6a98c5b6687ef798eda

Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2012-12-20T23:03:53Z', u'email': u'bob.grabar@10gen.com', u'name': u'Bob Grabar'}

Message: DOCS-491 review edits
Branch: master
https://github.com/mongodb/docs/commit/529f32c9a2f0c9a8f066873e2e4fb521f9020689

Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2012-12-19T20:24:39Z', u'email': u'bob.grabar@10gen.com', u'name': u'Bob Grabar'}

Message: DOCS-491 first draft
Branch: master
https://github.com/mongodb/docs/commit/e54bc217a070102aaf517e046ed96c4095926e94

Comment by auto [ 05/Jan/13 ]

Author:

{u'date': u'2012-12-19T19:52:36Z', u'email': u'bob.grabar@10gen.com', u'name': u'Bob Grabar'}

Message: DOCS-491 memory faqs
Branch: master
https://github.com/mongodb/docs/commit/5cdac48c260f9320e2035f37fa616805f534c053

Comment by Sam Kleinman (Inactive) [ 04/Oct/12 ]

Perhaps for a section for the crud documentation somewhere?

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