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From Andrew Purtell <apurt...@apache.org>
Subject Re: hbase mttr vs. hdfs
Date Fri, 13 Jul 2012 16:31:53 GMT
On Fri, Jul 13, 2012 at 6:27 AM, N Keywal <nkeywal@gmail.com> wrote:
> I looked at this part of hdfs code, and
> - it's not simple to add it in a clean way, even if doing it is possible.
> - i was wrong the the 3s hearbeat: the hearbeat is every 5 minutes
> actually. So changing this would not be without a lot of side effects.
> - as a side note HADOOP-8144 is interesting...
> So not writing the WAL on the local machine could be a good medium
> term option, that could likely be implemented with HDFS-385 (made
> available recently in "branch-1". I don't know what it stands for).

"branch-1" is the root of Hadoop 1, the next release should be
branched from there.

Changing the block placement policy for HBase WALs to avoid the local
machine is interesting. Those who could make use of this approach
would be those who:

    - Control their NameNode, it's classpath, and it's configuration

    - Would make the risk assessment that it is acceptable to plug
something in there from the HBase project

    - Are not using another block placement policy, either the one
from HDFS-RAID or their own

Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet
Hein (via Tom White)

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