Disabling the region replication doesn't remove secondaries regions

[#1]

Hi there,

I have some issue with disable the region replication for a table.

HBase version: 2.0.2.3.1.4.0-315

I have region replication enabled on a single table (REGION_REPLICATION => 2), which doubled amount of regions of the table. I keep it for a while and then changed region replication to 1 (via alter 'table', 'cf', {REGION_REPLICATION => '1'}).

What I expected to see is the number of region go down. But it wasn't happened.

What I tried:

• run major compaction
• restart region servers
• disable region_replica_replication

Does anyone know what is the procedure for disabling a region replication and how to get rid of secondaries regions?

[#2]

Hello @kras 

I was able to reproduce the concerned behaviour as well. Checking internally on the Steps to safely remove the Secondary Regions. Shall Update the Post once a Solution is found.

- Smarak

[#3 · Accepted solution]

Hello @kras 

Unfortunately, there is no Clean Way to remove such Secondary Regions. The concerned issue is tracked via HBASE-24720. 1 Quick Fix would be to create a Snapshot on say, Table_A (Which had RegionReplication reduced from 2 to 1), CloneSnapshot to a new Table (Table_B). Table_B would have 1 Region. 

- Smarak