[DOCS-1189] update/correct documentation for _secondaryThrottle Created: 03/Mar/13  Updated: 30/Oct/23  Resolved: 05/Mar/13

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

Type: Bug Priority: Major - P3
Reporter: Asya Kamsky Assignee: Sam Kleinman (Inactive)
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to DOCS-4341 update/correct documentation for _sec... Closed
is related to SERVER-7779 Tune _secondaryThrottle in order to m... Closed
Participants:
Days since reply: 10 years, 50 weeks, 2 days ago

 Description   

In all three places where _secondaryThrottle is mentioned
http://docs.mongodb.org/manual/tutorial/manage-chunks-in-sharded-cluster/
http://docs.mongodb.org/manual/tutorial/configure-sharded-cluster-balancer/#require-replication-before-chunk-migration-secondary-throttle
http://docs.mongodb.org/manual/reference/command/moveChunk/#movechunk

the following is unclear or needs to be fixed (for 2.4):

In 2.4 the default setting of _secondaryThrottle is 'true' (was false before).

When it's set to true, the following is what those three pages say:

"When set to true, MongoDB ensures replication to secondaries before allowing new chunk migrations."

  • this is misleading - MongoDB always ensures replication to majority before even entering critical section of migration of each chunk. This option will slow down copying and deleting by ensuring replication (to one secondary) of every single document during copy/delete. The key is this option add continuous checking of replication instead of "one time" basically.

"When enabled, secondary throttle puts a

{ w : 2 }

write concern on deletes and on copies, which means the balancer waits for those operations to replicate to at least one secondary before migrating chunks.When enabled, secondary throttle puts a

{ w : 2 }

write concern on deletes and on copies, which means the balancer waits for those operations to replicate to at least one secondary before migrating chunks."

This is exactly correct, except for the last clause - should be "before continuing with the next document" - this is happening in the midst of chunk migration.

"_secondaryThrottle (boolean) – Optional. Set to false by default. If set to true, the balancer waits for replication to secondaries while copying and deleting data during migrations."

This is 100% correct (for 2.2) I just want to make sure it got changed to "Set to true by default" (for 2.4).



 Comments   
Comment by auto [ 05/Mar/13 ]

Author:

{u'date': u'2013-03-04T18:17:03Z', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-1189: change to secondaryThrottle for 2.4
Branch: master
https://github.com/mongodb/docs/commit/2a0609ebce596cfcf7e986e24092f2bfbdcfbdeb

Comment by auto [ 04/Mar/13 ]

Author:

{u'date': u'2013-03-04T18:05:40Z', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-1189: minor change to secondaryThrotle note to correct language relevant to 2.2
Branch: v2.2
https://github.com/mongodb/docs/commit/61c3819d5fe82054666b9067ee955467c0144cbf

Comment by auto [ 04/Mar/13 ]

Author:

{u'date': u'2013-03-04T18:05:40Z', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-1189: minor change to secondaryThrotle note to correct language relevant to 2.2
Branch: master
https://github.com/mongodb/docs/commit/d307b3ffc6d03da66d7e706af60d69d29110d2bd

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