Clara Xiong created HBASE-15251:
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Summary: During a cluster restart, Hmaster thinks it is a failover
by mistake
Key: HBASE-15251
URL: https://issues.apache.org/jira/browse/HBASE-15251
Project: HBase
Issue Type: Bug
Components: master
Affects Versions: 0.98.15, 2.0.0
Reporter: Clara Xiong
Assignee: Clara Xiong
We often need to do cluster restart as part of release for a cluster of > 1000
nodes. We have tried our best to get clean shutdown but 50% of the time,
hmaster still thinks it is a failover. This increases the restart time from 5
min to 30 min and decreases locality from 95% to 5% since we didn't use a
balancer. We had a bug HBASE-14129 but the fix didn't work.
After adding more logging and inspecting the logs, we identified two things
that trigger the failover handling:
1. When Hmaster.AssignmentManager detects any dead servers on service manager
during joinCluster(), it determines this is a failover without further check. I
added a check whether there is even any region assigned to these servers.
During a clean restart, the regions are not even assigned.
2. When there are some leftover empty folders for log and split directories or
empty wal files, it is already treated as a failover. I added a check for that.
Although this can be resolved by manual clean up, it is still too tedious for
restarting a large cluster.
Patch will follow shortly.
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