[SERVER-26260] downgrade_replset.js and minor_version_downgrade_replset.js can fail due to v:2 index Created: 22/Sep/16  Updated: 19/Nov/16  Resolved: 23/Sep/16

Status: Closed
Project: Core Server
Component/s: Internal Code
Affects Version/s: None
Fix Version/s: 3.3.15

Type: Bug Priority: Major - P3
Reporter: David Storch Assignee: David Storch
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Backwards Compatibility: Fully Compatible
Operating System: ALL
Sprint: Query 2016-10-10
Participants:
Linked BF Score: 0

 Description   

These tests downgrade a replica set after running setFeatureCompatibiliityVersion:"3.2". The sFCV command returns "ok" after dropping a v:2 index on admin.system.version with "majority" writeConcern. This means that after receiving "ok", the index drop will not roll back, and all nodes will eventually become downgrade-able (since a node can only be downgraded until after the v:2 index is dropped). However, not all nodes are immediately downgrade-able. The test can attempt to downgrade a secondary that has not yet applied the dropIndex command. The node fails to start up with an error such as the following:

[js_test:minor_version_downgrade_replset] 2016-09-22T04:55:49.573+0000 d20011| 2016-09-22T04:55:49.572+0000 F INDEX    [initandlisten] Found an invalid index { v: 2, key: { version: 1 }, name: "incompatible_with_version_32", ns: "admin.system.version" } on the admin.system.version collection: this version of mongod cannot build new indexes of version number 2

In order to fix, the test should wait for the secondaries to catch up to the primary before attempting to downgrade.

If an operator encounters this situation in practice, the intention is that she or he restarts the node as 3.4 and tries to downgrade again once it has caught up.



 Comments   
Comment by Githook User [ 23/Sep/16 ]

Author:

{u'username': u'dstorch', u'name': u'David Storch', u'email': u'david.storch@10gen.com'}

Message: SERVER-26260 make tests await replication of FCV before downgrade
Branch: master
https://github.com/mongodb/mongo/commit/2009fc942491098a4bd17001a2278af471e3cb08

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