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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6358) Bulkloading from remote filesystem is problematic
Date Sat, 04 Aug 2012 00:47:03 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13428508#comment-13428508
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Todd Lipcon commented on HBASE-6358:
------------------------------------

bq. not breaking the current use case of non-local bulk loading when size or speed requirements
are modest

If the size and speed don't matter, then wouldn't you have just used a normal (non-bulk-load)
MR job to load the data?

I think funneling the load through one host basically defeats the purpose of bulk load. Perhaps
it could be available as an option for people just testing out, but I would prefer the default
to be a failure, and you have to enable the copy with a {{-copyToCluster}} or something.
                
> Bulkloading from remote filesystem is problematic
> -------------------------------------------------
>
>                 Key: HBASE-6358
>                 URL: https://issues.apache.org/jira/browse/HBASE-6358
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 0.94.0
>            Reporter: Dave Revell
>            Assignee: Dave Revell
>         Attachments: 6358-suggestion.txt, HBASE-6358-trunk-v1.diff, HBASE-6358-trunk-v2.diff,
HBASE-6358-trunk-v3.diff
>
>
> Bulk loading hfiles that don't live on the same filesystem as HBase can cause problems
for subtle reasons.
> In Store.bulkLoadHFile(), the regionserver will copy the source hfile to its own filesystem
if it's not already there. Since this can take a long time for large hfiles, it's likely that
the client will timeout and retry. When the client retries repeatedly, there may be several
bulkload operations in flight for the same hfile, causing lots of unnecessary IO and tying
up handler threads. This can seriously impact performance. In my case, the cluster became
unusable and the regionservers had to be kill -9'ed.
> Possible solutions:
>  # Require that hfiles already be on the same filesystem as HBase in order for bulkloading
to succeed. The copy could be handled by LoadIncrementalHFiles before the regionserver is
called.
>  # Others? I'm not familiar with Hadoop IPC so there may be tricks to extend the timeout
or something else.
> I'm willing to write a patch but I'd appreciate recommendations on how to proceed.

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