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HBase, mail # dev - Unscientific comparison of fully-cached zipfian reading


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Re: Unscientific comparison of fully-cached zipfian reading
Jean-Daniel Cryans 2013-05-23, 17:00
On Wed, May 22, 2013 at 10:36 AM, lars hofhansl <[EMAIL PROTECTED]> wrote:
> The 2000-4000 was just glancing at the HMaster page every now and then.

Ah sorry to have focused on that.

> The main point I was trying to make is that the only difference is the
> number of block cache misses (which is low in the SequentialRead case and
> very high in the RandomRead case), and the number of cache misses is almost
> the same as the number of a requests.

Re-reading your email, it seems we tested different things. In my
case, whatever cache I was hitting was the only one I was planning to
hit. If I was reading from the OS cache, I was disabling the block
cache.

> (The cache misses are traced via OpenTSDB).
>
> I'll repeat my test with a single region server only. Was your test in a
> cluster or with a single region server?

The whole setup is described in the document.

J-D