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https://issues.apache.org/jira/browse/YARN-666?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13656331#comment-13656331
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Siddharth Seth commented on YARN-666:
-------------------------------------
bq. Steps to upgrade a YARN cluster: do you think it would make sense to
upgrade the NMs first before upgrading the RM. If something goes wrong
(hopefully not), users can fall-back to the older version.
This really depends. There are situations which involve only an NM bug-fix. For
such cases, the RM doesn't even need to be upgraded/restarted. Also depends on
whether new APIs are being added to the RM which upgraded NMs may use.
bq. Considerations (Upgrading the MR runtime): Until YARN/MR go into separate
projects and release cycles, upgrading YARN alone (say 2.1.0 to 2.1.2)
shouldn't affect the clients (MR) - no?
This depends upon individual deployments. Sites may choose to deploy YARN/MR in
a way where they can be upgraded independently. The same example - MR 2.1.2
which contains AM/MR runtime fixes running against YARN 2.1.0. That's one of
the main goals of MR being user-land code. Until work preserving restart is
implemented, there should be a way to upgrade MR without affecting the cluster.
bq. I am assuming the version check will be similar to the one in HDFS-2983.
We can definitely learn from that - if we want to support more specific
versions than just the ones on individual protcols. I don't think YARN has any
version checks at the moment, other than the ones performed on API versions by
the RPC layer.
> [Umbrella] Support rolling upgrades in YARN
> -------------------------------------------
>
> Key: YARN-666
> URL: https://issues.apache.org/jira/browse/YARN-666
> Project: Hadoop YARN
> Issue Type: Improvement
> Affects Versions: 2.0.4-alpha
> Reporter: Siddharth Seth
> Attachments: YARN_Rolling_Upgrades.pdf
>
>
> Jira to track changes required in YARN to allow rolling upgrades, including
> documentation and possible upgrade routes.
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