From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p44AWvsl070797 for ; Wed, 4 May 2011 05:32:58 -0500 Received: from greer.hardwarefreak.com (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 170CC11CBB82 for ; Wed, 4 May 2011 03:36:34 -0700 (PDT) Received: from greer.hardwarefreak.com (mo-65-41-216-221.sta.embarqhsd.net [65.41.216.221]) by cuda.sgi.com with ESMTP id IoU5paGEUwcsQQ4C for ; Wed, 04 May 2011 03:36:34 -0700 (PDT) Received: from [192.168.100.53] (gffx.hardwarefreak.com [192.168.100.53]) by greer.hardwarefreak.com (Postfix) with ESMTP id 485416C0F7 for ; Wed, 4 May 2011 05:36:34 -0500 (CDT) Message-ID: <4DC12C2F.8060800@hardwarefreak.com> Date: Wed, 04 May 2011 05:36:31 -0500 From: Stan Hoeppner MIME-Version: 1.0 Subject: Re: XFS/Linux Sanity check References: <20110503031856.GA9114@dastard> In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com On 5/3/2011 11:05 AM, Paul Anderson wrote: > I'm still perfectly willing to buy good HW RAID cards, don't get me > wrong, but their main benefit to me will be the battery backed cache, > not the performance. Good RAID cards have many more advantages than battery cache and performance. One is moving a RAID card and its attached arrays from a failed host to a new one. In the case of the hardware RAID card usually all that is required is loading the HBA driver and mounting the filesystem. Such a move of an mdraid array is usually, well, not nearly as straightforward, to put it kindly. > Keep in mind that it is hard to balance a HW RAID card across multiple > SAS expanders -you can certainly get a -16e card of some sort, but > then it does ALL of the I/O to those 4 expanders ALL of the time. I'm note sure I know exactly what you mean here Paul. You seem to be talking about RAID card <-> drive chassis cabling flexibility and symmetrical bandwidth. The following two SAS expander/switch products are likely worth a quick read: http://www.intel.com/Products/Server/RAID-controllers/re-res2sv240/RES2SV240-Overview.htm http://www.lsi.com/channel/products/switch/sas6160/index.html Using an LSI 9260-4i single 8087 port RAID card, the Intel expander, and some 8087/8088 panel converters, one could attach *5* x 24 drive LSI 620J SAS JBOD chassis for a total of 120 drives with equal bandwidth to/from all drives, about 2GB/s total bandwidth, RAID ASIC limited. Few would want to connect 120 drives to such a single port RAID controller, but this example demonstrates that symmetry can be achieved across a large number of cascaded SAS expander ASICs (6 total) with a lot of drives. -- Stan _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs