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https://issues.apache.org/jira/browse/HBASE-23035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17179347#comment-17179347
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Pankaj Kumar edited comment on HBASE-23035 at 8/18/20, 3:58 AM:
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{quote}This jira change the "retain" assignment to round-robin assignment,
which is same with 1.x.x version. This change will make the failover faster and
improve availability.
{quote}
Yeah [~zghao] , failover will be faster and regions will be available soon but
this will impact the scan performance in non-cloud scenario.
But currently branch-1 retains the assinement during SCP if same RS came up
(please correct me if I miss something),
[https://github.com/apache/hbase/blob/c2e0cf989e4a86169219161d4d889db80288e636/hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/ServerCrashProcedure.java#L556]
IMO, we should make retain assignment configurable, so that user can decide as
per their use case.
was (Author: pankajkumar):
{quote}This jira change the "retain" assignment to round-robin assignment,
which is same with 1.x.x version. This change will make the failover faster and
improve availability.
{quote}
Yeah [~zghao] , failover will be faster and regions will be available soon but
this will impact the scan performance in non-cloud scenario.
But currently branch-1 retains the assinement during SCP if same RS came up
(please correct me if I miss something),
[https://github.com/apache/hbase/blob/c2e0cf989e4a86169219161d4d889db80288e636/hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/ServerCrashProcedure.java#L556]
IMO, we should make retain assignment configurable, so that user can decide s
per their use case.
> 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-alpha-1, 2.3.0, 2.2.1, 2.1.6
> Reporter: Guanghao Zhang
> Assignee: Guanghao Zhang
> Priority: Major
> Fix For: 3.0.0-alpha-1, 2.3.0, 2.1.7, 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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