Date: Mon, 5 Apr 2010 12:24:15 -0500 (CDT) From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us> To: Mikle Krutov <nekoexmachina@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: Fwd: Re: Strange ZFS performance Message-ID: <alpine.GSO.2.01.1004051219390.17188@freddy.simplesystems.org> In-Reply-To: <20100405095245.GA1152@takino.homeftp.org> References: <20100405073059.GA68655@icarus.home.lan> <20100405095245.GA1152@takino.homeftp.org>
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On Mon, 5 Apr 2010, Mikle Krutov wrote: > Any information i could provide to help us know what's the source of the problem? The svc_t value I saw posted in one of your mails was outrageously large. I suggest running iostat -x 30 while doing long-duration write and see what the actual values are. It seems likely that you are overrunning what your controller or disk is capable of handling and this is creating an I/O backlog which is far greater than what it would be if zfs had queued fewer simultaneous requests. It may be that tuning zfs_vdev_max_pending to a small value may help keep your controller from being overloaded. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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