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https://issues.apache.org/jira/browse/HDFS-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13889769#comment-13889769
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Todd Lipcon commented on HDFS-4239:
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Couple quick high-level comments:
- what's the authorization requirement here? The patch doesn't seem to do any
access control, but I wouldn't want a non-admin to make these changes.
- it seems odd that the "mark this volume dead" is non-persistent across
restarts. If a disk is "dying", I'm nervous that someone would mark it bad, and
then a later rolling restart of the service would revive it. Something like a
config file of "blacklisted volume IDs" and a 'refresh' RPC might be more
resistant to this type of issue -- or a marker file like "disallow_this_volume"
in the storage directory?
> 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, hdfs-4239_v2.patch, hdfs-4239_v3.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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