pkumarsinha commented on pull request #3463:
URL: https://github.com/apache/hadoop/pull/3463#issuecomment-928262899
> One other consideration is the behavior as it stands now for HDFS clusters
that have disabled xattrs with `dfs.namenode.xattrs.enabled=false`. (The
default for this property is `true` in recent versions, and with a lot of
people wanting at-rest encryption, it's become less common to set to `false`.)
>
> In current behavior, the NameNode will throw an `IOException` (not a more
specific subclass) that propagates to the client. DistCp will catch that and
throw its own `XAttrsNotSupportedException`.
>
> With this patch, the NameNode still throws `IOException`, but now DistCp
propagates that straight to the caller instead of throwing
`XAttrsNotSupportedException`. There is a risk that this could cause subtle
behavioral differences for higher-layer tooling (Oozie? Airflow?) that
coordinates DistCp jobs.
>
> I'm not certain there is a problem, but I agree with @steveloughran that
there is reason to be cautious. It's also difficult to anticipate if custom
`FileSystem` implementers have overridden and thrown a different exception,
despite the base class providing `UnsupportedOperationException` out of the box.
Thanks for the review @cnauroth. I would agree on your observation on
behavioral difference on dfs.namenode.xattrs.enabled being 'false'.
@steveloughran / @cnauroth Is there any recommendation here for the patch?
My only concern is and the one I have faced as well is when
dfs.namenode.xattrs.enabled='true' , the Xattr was supported by FS impl
(DistributedFileSystem.java) and despite I got the error that Xattr is not
supported. This hides the actual cause (probably an intermittent network issue
or so).
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