[SERVER-35034] Shard balancing failed Created: 16/May/18  Updated: 08/Jun/18  Resolved: 17/May/18

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

Type: Bug Priority: Major - P3
Reporter: Abhi Assignee: Kelsey Schubert
Resolution: Done Votes: 0
Labels: Bug
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

PROD


Operating System: ALL
Participants:

 Description   

Data balancing fails on MOngo cluster with 1 mongos and 3 mongods.. All the data for the collection fs.chunks stays in the same shard with the following error.

Env: Ubuntu- AWS m3.large,

 

error from sh.status()

6 : Failed with error 'could not acquire collection lock for test.fs.chunks to migrate chunk [{ : MinKey },{ : MaxKey }) :: caused by :: Lock for migrating chunk [{ : MinKey }, { : MaxKey }) in test.fs.chunks is taken.', from shard0001 to shard0000
3826 : Failed with error 'moveChunk failed to engage TO-shard in the data transfer: can't accept new chunks because there are still 7 deletes from previous migration', from shard0000 to shard0001
7655 : Failed with error 'moveChunk failed to engage TO-shard in the data transfer: can't accept new chunks because there are still 4 deletes from previous migration', from shard0001 to shard0000



 Comments   
Comment by Kelsey Schubert [ 17/May/18 ]

Hi abhisam,

Thanks for reporting this issue. This error message indicates that the balancer is waiting for documents on the receiving shard to be deleted (likely because some documents were previously migrated off of this shard) before starting a new migration to that shad.

From the information provided, I do not see anything to indicate a bug in the MongoDB server. For MongoDB-related support discussion please post on the mongodb-user group or Stack Overflow with the mongodb tag. A question like this involving more discussion would be best posted on the mongodb-users group.

Kind regards,
Kelsey

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