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https://issues.apache.org/jira/browse/HDFS-14771?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16916642#comment-16916642
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Stephen O'Donnell commented on HDFS-14771:
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The only change to the fsimage is in the index which is written at the end of
the file, and the change add some additional optional entries to the index.
On branch 3, we tested if this new image can be read by OIV and a namenode
without the patch, and both were fine. The reason is that the NN loops over the
sections of the index and skips those it does not expect to see. OIV looks for
specific entries in the index, and hence does not consider the newly added
entries.
We therefore concluded that this change could be added without up-versioning
the image as this change does not break backward compatibility.
{quote}
consider this feature is not ready completely, such as OIV support mentioned by
HDFS-14617 and so on
{quote}
On branch 3, OIV works with no issues. There are enhancements we can make to
OIV to improve it to do things in parallel and create an image with parallel
sections, but they are not needed to allow this feature to work on branch 3. If
a users needs to make use of OIV with HDFS-14617 applied, there are no
limitations there - OIV will work. I have not tested that on branch 2, but it
can be done as part of this Jira. Does OIV fail on branch 2 with this patch,
and if so do we have a log or stack trace to look into it further?
> Backport HDFS-14617 to branch-2 (Improve fsimage load time by writing
> sub-sections to the fsimage index)
> --------------------------------------------------------------------------------------------------------
>
> Key: HDFS-14771
> URL: https://issues.apache.org/jira/browse/HDFS-14771
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Affects Versions: 2.10.0
> Reporter: He Xiaoqiao
> Assignee: He Xiaoqiao
> Priority: Major
> Attachments: HDFS-14771.branch-2.001.patch
>
>
> This JIRA aims to backport HDFS-14617 to branch-2: fsimage load time by
> writing sub-sections to the fsimage index.
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