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https://issues.apache.org/jira/browse/HDFS-10887?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yongjun Zhang updated HDFS-10887:
---------------------------------
Attachment: HDFS-10887.001.patch
Upload patch rev 001.
The solution in this patch is to introduce two switches to "dfsadmin -metaSave"
command, to enable dumping out the blocks with fewer than minRepl replicas, and
dumping out the full block map.
When these switches are turned on, the patch requires safemode, because dumping
out the blocks may interfere with normal service.
This may appear a little weird, since normal "metaSave" doesn't require
safemode, and it's only required when the new switches are turned on. In case
that's an issue, I also implemented another solution that introduces a new
"hdfs debug" command, which is dedicated to for this purpose. But metaSave also
log some other useful information about blocks, so it may be better to dump
them altogether.
> Provide admin/debug tool to dump block map
> ------------------------------------------
>
> Key: HDFS-10887
> URL: https://issues.apache.org/jira/browse/HDFS-10887
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs, namenode
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-10887.001.patch
>
>
> From time to time, when NN restarts, we see
> {code}
> "The reported blocks X needs additional Y blocks to reach the threshold
> 0.9990 of total blocks Z. Safe mode will be turned off automatically.
> {code}
> We'd wonder what these blocks that still need block reports are, and what DNs
> they could possibly be located, what happened to these DNs.
> This jira to to propose a new admin or debug tool to dump the block map info
> with the blocks that have fewer than minRepl replicas.
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