From owner-freebsd-fs@FreeBSD.ORG Wed Jul 11 01:19:08 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 490EB1065674 for ; Wed, 11 Jul 2012 01:19:08 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from blade.simplesystems.org (blade.simplesystems.org [65.66.246.74]) by mx1.freebsd.org (Postfix) with ESMTP id 0A9608FC12 for ; Wed, 11 Jul 2012 01:19:07 +0000 (UTC) Received: from freddy.simplesystems.org (freddy.simplesystems.org [65.66.246.65]) by blade.simplesystems.org (8.14.4+Sun/8.14.4) with ESMTP id q6B1J6DC027267; Tue, 10 Jul 2012 20:19:06 -0500 (CDT) Date: Tue, 10 Jul 2012 20:19:05 -0500 (CDT) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: Jason Usher In-Reply-To: <1341946657.18535.YahooMailClassic@web122505.mail.ne1.yahoo.com> Message-ID: References: <1341946657.18535.YahooMailClassic@web122505.mail.ne1.yahoo.com> User-Agent: Alpine 2.01 (GSO 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (blade.simplesystems.org [65.66.246.90]); Tue, 10 Jul 2012 20:19:06 -0500 (CDT) Cc: freebsd-fs@freebsd.org Subject: Re: chaining JBOD chassic to server ... why am I scared ? (ZFS) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 11 Jul 2012 01:19:08 -0000 On Tue, 10 Jul 2012, Jason Usher wrote: > > But this scares me ... > > - two different power sources - so the "head unit" can lose power > independent of the JBOD device ... how well does that turn out ? Most of your concerns are things which have been normal for fiber channel based arrays for quite a few years already. SAS cables are shorter so there is a better chance that everything is on the same power and in the same rack. >From my limited experience, getting everything on the same power helps with managing things. > Just how well does ZFS v28 deal with these kind of situations, and > do I have a good reason to be awfully shy about doing this ? I have been on zfs mailing lists for many years and few of the issues reported have been due to ZFS. Usually problems are due to failing memory, bad cables, and SATA drives on SAS expanders. SAS disks work better in large arrays. There have been people running several hundred disks without problem. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/