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Sender: Alexander Motin <mavbsd@gmail.com>
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Date: Fri, 20 Jan 2012 12:51:54 +0200
From: Alexander Motin <mav@FreeBSD.org>
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To: Nikolay Denev <ndenev@gmail.com>
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Cc: Gary Palmer <gpalmer@freebsd.org>,
	FreeBSD-Current <freebsd-current@freebsd.org>,
	Dennis K?gel <dk@neveragain.de>, freebsd-geom@freebsd.org
Subject: Re: RFC: GEOM MULTIPATH rewrite
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On 01/20/12 10:09, Nikolay Denev wrote:
> Another thing I've observed is that active/active probably only makes sense if you are accessing single LUN.
> In my tests where I have 24 LUNS that form 4 vdevs in a single zpool, the highest performance was achieved
> when I split the active paths among the controllers installed in the server importing the pool. (basically "gmultipath rotate $LUN" in rc.local for half of the paths)
> Using active/active in this situation resulted in fluctuating performance.

How big was fluctuation? Between speed of one and all paths?

Several active/active devices without knowledge about each other with 
some probability will send part of requests via the same links, while 
ZFS itself already does some balancing between vdevs.

-- 
Alexander Motin