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https://issues.apache.org/jira/browse/HDFS-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14212757#comment-14212757
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Yongjun Zhang commented on HDFS-4239:
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HI [~qwertymaniac],
My bad that I did not notice your earlier comment
{quote}
I just noticed Steve's comment referring the same - should've gone through
properly before spending google cycles. I feel HDFS-1362 implemented would
solve half of this - and the other half would be to make the removals
automatic. Right now the checkDiskError does not eject if its slow - as long as
its succeed, which would have to be done via this JIRA I think. The re-add
would be possible via HDFS-1362.
{quote}
until now. So we need to use the functionality provided by HDFS-1362 to
automatically remove a sick disk. It seems the original goal of HDFS-4239 is
the same as HDFS-1362 (right?), and we can create a new jira for automatically
removing a sick disk?
Thanks.
> Means of telling the datanode to stop using a sick disk
> -------------------------------------------------------
>
> Key: HDFS-4239
> URL: https://issues.apache.org/jira/browse/HDFS-4239
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: stack
> Assignee: Yongjun Zhang
> Attachments: hdfs-4239.patch, hdfs-4239_v2.patch, hdfs-4239_v3.patch,
> hdfs-4239_v4.patch, hdfs-4239_v5.patch
>
>
> If a disk has been deemed 'sick' -- i.e. not dead but wounded, failing
> occasionally, or just exhibiting high latency -- your choices are:
> 1. Decommission the total datanode. If the datanode is carrying 6 or 12
> disks of data, especially on a cluster that is smallish -- 5 to 20 nodes --
> the rereplication of the downed datanode's data can be pretty disruptive,
> especially if the cluster is doing low latency serving: e.g. hosting an hbase
> cluster.
> 2. Stop the datanode, unmount the bad disk, and restart the datanode (You
> can't unmount the disk while it is in use). This latter is better in that
> only the bad disk's data is rereplicated, not all datanode data.
> Is it possible to do better, say, send the datanode a signal to tell it stop
> using a disk an operator has designated 'bad'. This would be like option #2
> above minus the need to stop and restart the datanode. Ideally the disk
> would become unmountable after a while.
> Nice to have would be being able to tell the datanode to restart using a disk
> after its been replaced.
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