[
https://issues.apache.org/jira/browse/HDFS-7208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14163169#comment-14163169
]
Ming Ma commented on HDFS-7208:
-------------------------------
We can work around it by setting dfs.datanode.failed.volumes.tolerated to zero
so that as long as there is one disk failure, NN will remove that DN. For the
fix, there are several possible approaches.
1. Have DN notify NN via DatanodeProtocol.reportBadBlocks for these blocks.
2. Modify DatanodeProtocol.errorReport so that DN can pass storage id to NN.
3. Have DN send blockReport for this failed storage so that NN can detect that.
Appreciate any suggestions.
> NN doesn't schedule replication when a DN storage fails
> -------------------------------------------------------
>
> Key: HDFS-7208
> URL: https://issues.apache.org/jira/browse/HDFS-7208
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Ming Ma
>
> We found the following problem. When a storage device on a DN fails, NN
> continues to believe replicas of those blocks on that storage are valid and
> doesn't schedule replication.
> A DN has 12 storage disks. So there is one blockReport for each storage. When
> a disk fails, # of blockReport from that DN is reduced from 12 to 11. Given
> dfs.datanode.failed.volumes.tolerated is configured to be > 0, NN still
> considers that DN healthy.
> 1. A disk failed. All blocks of that disk are removed from DN dataset.
>
> {noformat}
> 2014-10-04 02:11:12,626 WARN
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Removing
> replica BP-1748500278-xx.xx.xx.xxx-1377803467793:1121568886 on failed volume
> /data/disk6/dfs/current
> {noformat}
> 2. NN receives DatanodeProtocol.DISK_ERROR. But that isn't enough to have NN
> remove the DN and the replicas from the BlocksMap. In addition, blockReport
> doesn't provide the diff given that is done per storage.
> {noformat}
> 2014-10-04 02:11:12,681 WARN org.apache.hadoop.hdfs.server.namenode.NameNode:
> Disk error on DatanodeRegistration(xx.xx.xx.xxx,
> datanodeUuid=f3b8a30b-e715-40d6-8348-3c766f9ba9ab, infoPort=50075,
> ipcPort=50020,
> storageInfo=lv=-55;cid=CID-e3c38355-fde5-4e3a-b7ce-edacebdfa7a1;nsid=420527250;c=1410283484939):
> DataNode failed volumes:/data/disk6/dfs/current
> {noformat}
> 3. Run fsck on the file and confirm the NN's BlocksMap still has that replica.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
