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https://issues.apache.org/jira/browse/HBASE-23035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16935637#comment-16935637
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Guanghao Zhang edited comment on HBASE-23035 at 9/24/19 1:21 AM:
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Read HBASE-18946 again. So the initial problem is "Region replicas should be
assigned to different servers". But the fix looks not good in HBASE-18946. It
tried to round-robin assign when create table with region replica. And retain
the old location for region replica when failover. But load balancer still have
chance to break this and assign region replica to same server? I thought the
initial problem should be fixed by load balancer. And the failover no need
retain the old deployment.
was (Author: zghaobac):
Read HBASE-18946 again. So the initial problem is "Region replicas should be
assigned to different servers". But the fix looks not good in HBASE-18946. It
tried to round-robin assign when create table with region replica. And retain
the old location for region replica when failover. But load balancer still have
change to break this and assign region replica to same server? I thought the
initial problem should be fixed by load balancer. And the failover no need
retain the old deployment.
> Retain region to the last RegionServer make the failover slower
> ---------------------------------------------------------------
>
> Key: HBASE-23035
> URL: https://issues.apache.org/jira/browse/HBASE-23035
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 3.0.0, 2.3.0, 2.2.1, 2.1.6
> Reporter: Guanghao Zhang
> Assignee: Guanghao Zhang
> Priority: Major
> Fix For: 3.0.0, 2.3.0, 2.2.2
>
>
> Now if one RS crashed, the regions will try to use the old location for the
> region deploy. But one RS only have 3 threads to open region by default. If a
> RS have hundreds of regions, the failover is very slower. Assign to same RS
> may have good locality if the Datanode is deploied on same host. But slower
> failover make the availability worse. And the locality is not big deal when
> deploy HBase on cloud.
> This was introduced by HBASE-18946.
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