Date: Thu, 14 Feb 2013 14:00:30 +0100 From: Sven Brandenburg <sven@crashme.org> To: freebsd-scsi@freebsd.org Subject: Re: Increase mps sequential read performance with ZFS/zvol Message-ID: <511CDFEE.10307@crashme.org> In-Reply-To: <20130205023609.GA99100@FreeBSD.org> References: <510E987C.4090509@oxit.fi> <510E9FD1.5070907@freebsd.org> <20130205023609.GA99100@FreeBSD.org>
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On 02/05/2013 03:36 AM, John wrote: [..] > Gmultipath is used to bind the disks such that each disk can be > addressed by either controller and the I/O balanced. > > The zfs pool consists of 24 mirrors, each pair one from each shelf. > The multipaths are rotated such that I/O is balanced between shelves > and controllers. [..] Not sure if this applicable to your problem but in a similar setup like yours, I found gmultipath in round-robin mode to be terrible for performance. Afaik the D2700 have their own caching controllers and may shield you from this, but if HBAs are directly connected to the disk, concurrent IO requests from two 'sides' via gmultipath seem to terrorize them, cutting effective read performance down by at least 75%. Try to switch gmultipath to active/passive. I bet its faster :) regards, Sven
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