[
https://issues.apache.org/jira/browse/HDFS-2971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13213943#comment-13213943
]
Suresh Srinivas commented on HDFS-2971:
---------------------------------------
bq. The highest gen stamp in an image or log tells you if it's older than
another file system.
Do you mean to say, when you have multiple images/edits, the one with the
highest gen stamp is the latest? Shouldn't transaction ID introduced in
HDFS-1073 be used for this purpose? Or are you planning do this in an older
release, if so updating the target version would help.
bq. You don't want to update to saved image/logs that are old as that can cause
data loss (you start the NN and it starts removing blocks with a new GS).
Images are never updated.
For editlog, assuming it is what I said previously, loading older image + older
editlog pair would result in system coming up with incomplete data and hence
loss of data is expected.
So the tools that are proposed, is this some thing that an operator would use
to determine the latest edits/image. I fail to understand who and how this will
be used.
> some improvements to the manual NN metadata recovery tools
> ----------------------------------------------------------
>
> Key: HDFS-2971
> URL: https://issues.apache.org/jira/browse/HDFS-2971
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: libhdfs
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: 2012-02-17_0001-OEV-enhancements-pt.-2.patch,
> HDFS-2971__print_highest_generation_stamp.txt
>
>
> Some improvements to the manual NN metadata recovery tools.
> Specifically, we want the Offline Edit Viewer (oev) tool to prints out the
> highest generation stamp that was encountered when processing the edit log.
> We also want OEV to look for large gaps in the generation stamp, as these can
> indicate corruption. The minimum gap to look for should be configurable with
> -G or --genStampGap.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
