[
https://issues.apache.org/jira/browse/HADOOP-5027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12667731#action_12667731
]
Konstantin Shvachko commented on HADOOP-5027:
---------------------------------------------
Since this is about block reports in the context of appends the following
question should be appropriate here. May be also related to "tmp" directories
discussion in HADOOP-4663.
When I open a file for append the last block of the file is copied from the
main storage to a tmp directory to be treated as if it is just being created.
Then on the next blockReport since the block is not in the main storage it will
not be reported to the name-node. And the name-node should mark it as
under-replicated triggering replication process. Replication will not be able
to proceed as all replicas on other machines are in the same state, that is in
tmp directory. Is that a problem?
The main problem here I think is that the name-node removes the location of the
replica if it was not reported during a block report. If all 3 nodes report
that they don't have the block, the block will become not readable, that is the
name-node cannot give clients any locations of the block.
> Block report processing should compare gneration stamp
> ------------------------------------------------------
>
> Key: HADOOP-5027
> URL: https://issues.apache.org/jira/browse/HADOOP-5027
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Reporter: Tsz Wo (Nicholas), SZE
> Fix For: 0.19.1
>
> Attachments: 5027_20090114.patch
>
>
> If a reported block has a different generation stamp then the one stored in
> the NameNode, the reported block will be considered as invalid. This is
> incorrect since blocks with larger generation stamp are valid.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
