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https://issues.apache.org/jira/browse/HDFS-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13883728#comment-13883728
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Jimmy Xiang commented on HDFS-4239:
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We can release the lock after the volume is marked down. No new block will be
allocated to this volume. How about those blocks on this volume being writing?
The writing could take forever, for example, a rarely updated HLog file. I was
thinking to fail the writing pipeline so that the client can set up another
pipeline. Any problem with that?
> 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: Jimmy Xiang
> Attachments: hdfs-4239.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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