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From Sean Busbey <>
Subject Re: ISAM file location vs. read performance
Date Sun, 12 Jan 2014 23:17:39 GMT
On Sun, Jan 12, 2014 at 4:42 PM, William Slacum <> wrote:

> Some data on short circuit reads would be great to have.
What kind of data are you looking for? Just HDFS read rates? or
specifically Accumulo when set up to make use of it?

> I'm unsure of how correct the "compaction leading to eventual locality"
> postulation is. It seems, to me at least, that in the case of a multi-block
> file, the file system would eventually try to distribute those blocks
> rather than leave them all on a single host.

I know in HBase set ups, it's common to either disable the HDFS Balancer or
just disable for a namespace containing the part of the filesystem that
handles HBase. Otherwise, when the blocks are moved off to other hosts you
get performance degradation until compaction can happen again. I would
expect the same thing ought to be done for Accumulo.

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