[SOLR-4354] Replication should perform full copy if slave's generation higher than master's

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 4.1
• Fix Version/s: 4.2
• Component/s: replication (java)
• Assignee: Mark Miller
• Reporter: Amit Nithian
• Created: 25/Jan/13 07:23
• Updated: 10/May/13 10:32
• Resolved: 25/Jan/13 17:46

Description

We have dual masters each incrementally indexing from our MySQL database and sit behind a virtual hostname in our load balancer. As such, it's possible that the generation numbers between the masters for a given index are not in sync. Slaves are configured to replicate from this virtual host (and pin based on source/dest IP hash) so we can add and remove masters as necessary (great for maintenance).

For the most part this works but we've seen the following happen:

• Slave has been pulling from master A
• Master A goes down for maint and now will pull from master B (which has a lower generation number for some reason than master A).
• Slave now tries to pull from master B (has higher index version than slave but lower generation).
• Slave downloads index files, moves them to the index/ directory but these files are deleted during the doCommit() phase (looks like older generation data is deleted).
• Index remains as-is and no change.

Issue Links

• duplicates: SOLR-4303 On replication, if the generation of the master is lower than the slave we need to force a full copy of the index.