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https://issues.apache.org/jira/browse/HBASE-1442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12711262#action_12711262
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Evgeny Ryabitskiy edited comment on HBASE-1442 at 5/20/09 11:10 AM:
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In future we can move Region's assignment to HRSs to make everything scalable.
* But question: how to choose that HRS that should make decisions about
assignment?
One easy way is to put assignment managing on HRS that holds META regions.
So each HRS that holds at least one METARegion should manage assignment for all
User Regions in that META.
* Ok, so HRS that holds META manages Region's assignment in that META, but how
to decide where to assign that Regions? to which HRS?
We can use Hash Ring for METARegions to get maping METARegion -> HRS. Like in
every DHT but simple variant without replication.
So in the result: cluster start/stop will take as much time as it will take to
slowest HRS holding META to manage regions in that META.
just thoughts that comes after my small research :) Not sure if it already
appeared here...
was (Author: apparition):
In future we can move Region's assignment to HRSs to make everything
scalable.
* But question: how to choose that HRS that should make decisions about
assignment?
One easy way is to put assignment managing on HRS that holds META regions.
So each HRS that holds at least one METARegion should manage assignment for all
User Regions in that META.
* Ok, so HRS that holds META manages Region's assignment in that META, but how
to decide where to assign that Regions? to which HRS?
We can use Hash Ring for METARegions to get maping METARegion -> HRS. Like in
every DHT but simple variant without replication.
just thoughts that comes after my small research :) Not sure if it already
appeared here...
> Large number of regions slows down start and stop of HBase clusters
> -------------------------------------------------------------------
>
> Key: HBASE-1442
> URL: https://issues.apache.org/jira/browse/HBASE-1442
> Project: Hadoop HBase
> Issue Type: Improvement
> Reporter: Lars George
>
> A cluster with tables that have thousands of regions will take a long time to
> start and shut down.
> During the start the META table is scanned which takes a long time. Also at
> least minor compaction are performed that add to the delay as by default
> there is a 20sec wait time between the each compaction.
> Also region assignment may be not right assigning 10 regions at a time while
> unbalancing the servers.
> Shutting a large cluster down also takes a long time before everything is
> persisted and shut down orderly. Times in excess of 10 minutes have been
> noted. It needs to be investigated where this time is spent.
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