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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: replication - how do I know the status?
Date Thu, 13 Sep 2012 21:48:15 GMT
On Thu, Sep 13, 2012 at 2:28 PM, Neil Yalowitz <neilyalowitz@gmail.com> wrote:
> This is a great answer, I can see that particular ganglia metric sharply
> increased when the issue began.  Thanks much.


> One followup question:
> Can a distressed slave cluster cause performance issues on the master
> cluster?  It appears our performance problem was occurring on the slave
> peer, but the master cluster almost crashed as well.  I'm trying to
> determine if that was a coincidence or something more...

That's a tougher one, but FWIW the work required on the master cluster
is low compared to what the slave has to do; the master just needs to
read a bunch of edits and send them whereas the slave has to write
them to the WAL, add them to the MemStore, eventually flush and
compact, etc.

Also if you had a big MR job that ran on the master and that inserted
a lot of data, I would assume that it made everything slower. If it's
also what caused swapping then it would explain a lot.


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