[SERVER-25516] Add setParameter option to 3.2 to prevent the replica set monitor from ever giving up on monitoring a set Created: 09/Aug/16  Updated: 03/Apr/19  Resolved: 12/Sep/16

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: None
Fix Version/s: 3.2.10

Type: Bug Priority: Major - P3
Reporter: Spencer Brody (Inactive) Assignee: Andy Schwerin
Resolution: Done Votes: 0
Labels: code-and-test
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Documented
is documented by DOCS-8793 Document changes to removeShard proce... Closed
Related
related to SERVER-23192 mongos and shards will become unusabl... Closed
Backwards Compatibility: Fully Compatible
Operating System: ALL
Sprint: Sharding 2016-09-19
Participants:
Case:

 Description   
Issue Status as of Oct 07, 2016

ISSUE DESCRIPTION AND IMPACT
As a workaround for SERVER-23192, MongoDB 3.2.10 introduced an option where a node never stops monitoring a replica set once it has started, no matter how long it appears to be down for. Using this option means you can encounter problems if you remove a shard then add back a shard with the same replica set name.

This parameter is set to false by default, and can be set by executing following command:

db.adminCommand( {setParameter: 1, 'timeOutMonitoringReplicaSets': true} )

DIAGNOSIS AND AFFECTED VERSIONS
This option is included MongoDB 3.2.10 and subsequent releases of MongoDB 3.2. Please note that it is not included in MongoDB 3.4.

REMEDIATION AND WORKAROUNDS
If the operator wishes to re-add the shard using different hosts at a later date, the operator has two choices:

  1. Restart all the affected nodes.
  2. Toggle the timeOutMonitoringReplicaSets server parameter introduced in SERVER-25516 from false to true on each affected node. Once the the shard is discovered, switch timeOutMonitoringReplicaSets back to false, usually this process takes about two minutes.
Original description

As a workaround for SERVER-23192 on 3.2 we can introduce an option where we never stop monitoring a replica set once we've started, no matter how long it appears to be down for. Using this option means you can encounter problems if you remove a shard then add back a shard with the same replica set name.



 Comments   
Comment by Githook User [ 12/Sep/16 ]

Author:

{u'username': u'andy10gen', u'name': u'Andy Schwerin', u'email': u'schwerin@mongodb.com'}

Message: SERVER-25516 By default, never stop monitoring replica sets in mongos.
Branch: v3.2
https://github.com/mongodb/mongo/commit/5cb9cc75fe39e183b004ca3f0b641098d06e279c

Comment by Andy Schwerin [ 08/Sep/16 ]

Re-opening because, per offline discussion, we're going to change the default value of the parameter to "never stop monitoring a set".

Comment by Githook User [ 26/Aug/16 ]

Author:

{u'username': u'stbrody', u'name': u'Spencer T Brody', u'email': u'spencer@mongodb.com'}

Message: SERVER-25516 Add setParameter to prevent giving up on monitoring replica sets
Branch: v3.2
https://github.com/mongodb/mongo/commit/bca02ccf20c3165fe13e8cf19bb4cff2872f7590

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