[SERVER-8752] Improve visibility of Balancer operation Created: 27/Feb/13  Updated: 22/Mar/17  Resolved: 11/Aug/14

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: None
Fix Version/s: 2.7.5

Type: Improvement Priority: Major - P3
Reporter: Andre de Frere Assignee: David Hows
Resolution: Done Votes: 5
Labels: cap-ticket-needed, community-team, pull-request
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
is depended on by DOCS-5071 Document config.actionlog collection Closed
is depended on by DOCS-3400 Comment on: "manual/reference/method/... Closed
Related
related to SERVER-14882 Modify sh.status to include output fr... Closed
Tested
Sprint: Server 2.7.3, Server 2.7.4, Server 2.7.5
Participants:

 Description   

What the balancer is actually currently doing can be opaque. In times when the shards are out of balance and do not appear to be balancing, and where there is no good indication in the logs indicating an issue with the balancer, it would be useful to have some way of querying what the balancer is actually doing.

The locks collection does not give you enough information, as you can only reliably tell if the balancer is on or not, or if it is currently in a balancing round. You can't tell if the balancer is currently calculating, or moving a chunk or not able to move chunks for some reason that is not an error. In either case, having more insight into what the balancer is currently doing would help diagnose issues.

If there is a location or object to store state of the balancer this could make it available to be queried from the shell or drivers, given that additional logging may not be the solution



 Comments   
Comment by Githook User [ 14/Aug/14 ]

Author:

{u'username': u'daveh86', u'name': u'daveh86', u'email': u'howsdav@gmail.com'}

Message: SERVER-8752 Fixed 'what' field value in Actionlog

Closes #744

Signed-off-by: Benety Goh <benety@mongodb.com>
Branch: master
https://github.com/mongodb/mongo/commit/1f5428d02542074a49e054172f4dac46b06fd97b

Comment by Benety Goh [ 14/Aug/14 ]

Author:

{u'username': u'daveh86', u'name': u'David Hows', u'email': u'howsdav@gmail.com'}

Message: SERVER-8752 Add config.actionlog
Branch: master
https://github.com/mongodb/mongo/commit/cf2917a1e94959a696642407425f89fe14ccb1b4

Comment by David Hows [ 27/Jan/14 ]

Little bit of scope creep. SERVER-12472 is around failing a migration when indexes are missing. Increasing visibility would be worthwhile for that case too.

There is also an option for a command which would review all the indexes on each of the shards.

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