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https://issues.apache.org/jira/browse/HBASE-24152?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17104054#comment-17104054
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Zheng Wang commented on HBASE-24152:
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{quote}Why not just give host3 a more attractive score?
Up the weights for host1 and host2 because they are 'only' hdd.
Starting a new scoring that is exclusively about SSD doesn't seem like the
right direction. Better if when scoring a host for the balancer, there is one
scoring only which has taking into account all factors -- count of regions
already assigned, as well as whether host host has SSD or not.
{quote}
Your proposal is target to move more regions to the hosts which has ssd, but it
has three disadvantages:
1、Need to get the config of dfs.datanode.data.dir from namenode to judge
whether a host has ssd or not.
2、The hosts may be mixed storage that have both hdd and ssd, so we can not easy
to specify a consistent weight for them.
3、Only make effect after compaction.
The proposal in this issue is about locality, target to the local replica is
also the ssd replica, it has two advantages:
1、No need to get config from namenode.
2、Could make effect immediately after movement.
{quote}
Is this feature for the case where only some hosts in the cluster have SSD?
{quote}
Yeah, we do not need to worry about that these hosts will has too many regions,
restrained by the effect of RegionCountSkewCostFunction.
Thanks.
> Add ServerSsdLocalityCostFunction to StochasticLoadBalancer
> -----------------------------------------------------------
>
> Key: HBASE-24152
> URL: https://issues.apache.org/jira/browse/HBASE-24152
> Project: HBase
> Issue Type: New Feature
> Components: Balancer
> Reporter: Zheng Wang
> Assignee: Zheng Wang
> Priority: Major
>
> When use ONE_SSD storagy policy, or ALL_SSD but has not enough SSD, there
> will be some hdfs blocks on DISK and others on SSD,so it is reasonable to
> consider the locality of ssd for StochasticLoadBalancer.
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