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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HBASE-3144) Freeze and thaw for regions and/or regionservers
Date Wed, 16 Jul 2014 23:15:07 GMT

     [ https://issues.apache.org/jira/browse/HBASE-3144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Andrew Purtell resolved HBASE-3144.

    Resolution: Not a Problem

> Freeze and thaw for regions and/or regionservers
> ------------------------------------------------
>                 Key: HBASE-3144
>                 URL: https://issues.apache.org/jira/browse/HBASE-3144
>             Project: HBase
>          Issue Type: New Feature
>          Components: regionserver
>            Reporter: Karthik Ranganathan
> When frozen, a region would not flush new files or delete old files.
> Context:
> Was talking to Dhruba about the possibility of a fast intra-cluster copy, and he says
it is totally do-able. The idea is this: if there is a HBase table that is very large (multiple
terabytes) then distcp takes a long time. The major bottleneck is the cross rack network transfer
time. We can easily avoid this by going to each of the block replicas and replicating them
on the same machine from one disk to another. For our infrastructure setup, this could make
hours of copy time seconds.
> If we are able to implement the above, then copying an entire HBase table will only take
seconds. Now we just have to ensure that the region files do not "change" during this period
- so we need to disable compactions and flushes. Hence the need for the freeze and thaw of
regions in a region server.
> The way this would work is to flush a region, freeze it, snapshot it, then thaw it and
let normal operations proceed. The snapshot would proceed at disk read/write speed so it should
take only seconds per region.

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