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https://issues.apache.org/jira/browse/HDFS-6293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13995711#comment-13995711
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Haohui Mai commented on HDFS-6293:
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bq. If we only think about this, we can deprecate OIV and NN's ability to save
the old format, once we have a long term alternative solution.
My only concern is that the legacy fsimage / oiv are somewhat broken already,
they are slightly out of dated and contain incomplete information. For example,
features like ACL and rolling upgrades are in the new PB-based fsimage only.As
the system continue to evolve down the road (e.g., HDFS-2006), the use cases of
the legacy fsimage / oiv are limited to what we have right now, and it's
unlikely that the new use cases will be addressed.
Thanks to PB and the new format, I think we have a much better story on the
compatibility of the fsimage. I think it might be worthwhile to consider to
keep the format stable in 2.x and to externalize the responsibility of
analyzing the fsimage.
> Issues with OIV processing PB-based fsimages
> --------------------------------------------
>
> Key: HDFS-6293
> URL: https://issues.apache.org/jira/browse/HDFS-6293
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.4.0
> Reporter: Kihwal Lee
> Assignee: Haohui Mai
> Priority: Blocker
> Attachments: HDFS-6293.000.patch, HDFS-6293.001.patch,
> HDFS-6293.002-save-deprecated-fsimage.patch,
> HDFS-6293_sbn_ckpt_retention.patch,
> HDFS-6293_sbn_ckpt_retention_oiv_legacy.patch, Heap Histogram.html
>
>
> There are issues with OIV when processing fsimages in protobuf.
> Due to the internal layout changes introduced by the protobuf-based fsimage,
> OIV consumes excessive amount of memory. We have tested with a fsimage with
> about 140M files/directories. The peak heap usage when processing this image
> in pre-protobuf (i.e. pre-2.4.0) format was about 350MB. After converting
> the image to the protobuf format on 2.4.0, OIV would OOM even with 80GB of
> heap (max new size was 1GB). It should be possible to process any image with
> the default heap size of 1.5GB.
> Another issue is the complete change of format/content in OIV's XML output.
> I also noticed that the secret manager section has no tokens while there were
> unexpired tokens in the original image (pre-2.4.0). I did not check whether
> they were also missing in the new pb fsimage.
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