Date: Fri, 20 Jan 2012 12:51:54 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Nikolay Denev <ndenev@gmail.com> 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 Message-ID: <4F19474A.9020600@FreeBSD.org> In-Reply-To: <059C17DB-3A7B-41AA-BF91-2F8EBAF17D01@gmail.com> References: <4EAF00A6.5060903@FreeBSD.org> <05E0E64F-5EC4-425A-81E4-B6C35320608B@neveragain.de> <4EB05566.3060700@FreeBSD.org> <20111114210957.GA68559@in-addr.com> <059C17DB-3A7B-41AA-BF91-2F8EBAF17D01@gmail.com>
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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
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