[DOCS-3679] Document that addShard can break existing balance Created: 30/Jun/14  Updated: 16/Mar/15  Resolved: 09/Jul/14

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: v1.3.8

Type: Improvement Priority: Critical - P2
Reporter: Alexander Komyagin Assignee: Sam Kleinman (Inactive)
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

http://docs.mongodb.org/manual/reference/command/addShard/


Issue Links:
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Participants:
Days since reply: 9 years, 32 weeks ago

 Description   

When you have a lot of sharded collections perfectly balanced across X shards, adding a new shard will cause all existing collections to rebalance across X+1 shards, which might take some time.

I suggest to put a note about this in our docs, as some users apparently expect mongoS to only rebalance newly sharded collections.



 Comments   
Comment by Githook User [ 09/Jul/14 ]

Author:

{u'username': u'tychoish', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-3679: adding note about balancing to addShard pages
Branch: master
https://github.com/mongodb/docs/commit/e2b7d708f263e7f900a371985ff74a91195827aa

Comment by sam flint [ 30/Jun/14 ]

This is relevant when you are doing time series in collections, because you want to expand the sharded cluster for the future but not worry about balancing the past. I had to turn the balancer off the use the sh.diasbleBalacning() for all previous collections. Then I had to re create all future collections to use the 4 shards instead of 3. This was more of an over site on my part but it was extremely hard to fix.

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