[DOCS-545] Documentation on backing up a sharded cluster is incorrect Created: 24/Sep/12  Updated: 30/Oct/23  Resolved: 30/Oct/12

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

Type: Bug Priority: Major - P3
Reporter: William Zola Assignee: Sam Kleinman (Inactive)
Resolution: Done Votes: 1
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
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Related
related to SERVER-3456 Running fsync+lock on config server d... Closed
Participants:
Days since reply: 11 years, 16 weeks, 1 day ago

 Description   

The preferred method for backing up a sharded cluster is as follows:

  • Stop the balancer using sh.stopBalancer()
  • Shut down one of the config servers
  • Perform a backup on all of the shards (filesystem backup preferred)
  • Back up the shut down config server (filesystem backup preferred)
  • Restart the down config server
  • Restart the balancer using sh.startBalancer()

This procedure is not documented in the manual. In addition, the procedure which is documented in the manual has the following errors:
1) It says to shut down the balancer using direct operations on the 'config.settings' collection. This is incorrect: the correct method is to use sh.stopBalancer()

2) If you shut down the balancer using direct operations, there is a delay between the time you issue the command and the time that the balancer stops. If you don't wait for the balancer to fully stop, then the backup will be inconsistent. One of the features of using sh.stopBalancer() is that it will wait for the balancer to fully stop

3) Locking the shards is not necessary if you are doing filesystem backups using snapshots: it's only necessary if you're using OS-level file copies

I suggest replacing the current procedure in the manual with the above procedure, and then suggesting stopping the balancer as an alternative method.



 Comments   
Comment by Sam Kleinman (Inactive) [ 30/Oct/12 ]

Please reopen if you think that the commit does not resolve the issue.

Comment by auto [ 30/Oct/12 ]

Author:

{u'date': u'2012-10-30T14:02:52-07:00', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-545 and DOCS-678 clarifying sharded backup procedures
Branch: master
https://github.com/mongodb/docs/commit/416b7ea57df999c52bdc173fd28e1ddc66539d81

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