Xiaolin Ha created HBASE-22767:
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             Summary: System table RIT STUCK if their RSGroup has no highest 
version RSes
                 Key: HBASE-22767
                 URL: https://issues.apache.org/jira/browse/HBASE-22767
             Project: HBase
          Issue Type: Bug
          Components: rsgroup
            Reporter: Xiaolin Ha
            Assignee: Xiaolin Ha


AM chooses highest version region servers as participants for system tables, 
including META table. If system table group has no highest version region 
servers, then the reassignment of their regions will be always the BOGUS server 
defined in RSGroup. 

In our test environment using branch-2.2, we isolate system tables in a rsgroup 
containing only one server. And when upgrading RSs, we have met the problem 
that META is always assigned to the BOGUS server while the group server has 
already been online for a while. META RIT is stuck and can not be recovered by 
hbck2.

I made a UT reproduce this problem, steps are:

1. add a group, move 1 server to it;

2. move meta table to the group;

3. restart the group server and downgrade its version;

4. meta rit stuck.

 

ROOT cause is AM filters highest version RSs for system tables. So if we do not 
change the versions of system table group servers, but upgrade the versions of 
other group servers, then if there is reassignment for any system tables, such 
as balancer moving their regions, RIT STUCK!! 

 

 

 



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