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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HDFS-4239) Means of telling the datanode to stop using a sick disk
Date Fri, 14 Nov 2014 19:39:36 GMT

     [ https://issues.apache.org/jira/browse/HDFS-4239?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Yongjun Zhang resolved HDFS-4239.
---------------------------------
    Resolution: Duplicate

Hi Stack,

This issue turned out to be a duplicate of HDFS-1362, which is resolved now.

I'm closing this jira as duplicate. Please re-open if you think there is additional issue
to be addressed there.

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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