From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Landman Subject: Re: HBA Adaptor advice Date: Fri, 20 May 2011 08:48:23 -0400 Message-ID: <4DD66317.70400@gmail.com> References: <4DD50C89.8060006@wildgooses.com> <20110520020853.GC4759@bitfolk.com> <4DD61948.8050302@wildgooses.com> <4DD65C18.5090804@gmail.com> <20110520183413.64fe3ccc@natsu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110520183413.64fe3ccc@natsu> Sender: linux-raid-owner@vger.kernel.org To: Roman Mamedov Cc: Ed W , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 05/20/2011 08:34 AM, Roman Mamedov wrote: > On Fri, 20 May 2011 08:18:32 -0400 > Joe Landman wrote: > >> Second off, you can turn any of the expensive RAID cards into an 'JBOD' >> by doing something like this: >> >> 1) have the unit configured in RAID mode >> >> 2) build virtual disks out of single drives, as RAID0. >> >> 3) iterate 2 until you exhaust your drives. >> >> 4) make sure you prevent these drives from messing with your boot drive >> order ... some bioses "helpfully" reorganize new drives for you by >> messing with this list. >> >> Once the drive is a 1 disk RAID0, you get the cache, and the BBU for the >> cache. Yeah, its a little weird. But it does work (we've done this >> with some LSI8888's). > > But can you then access SMART of the individual drives? I don't view the loss of direct SMART access as a bad thing ... most of the RAID cards will give you CLI access to this data, if in a convoluted manner. SMART's utility is generally pretty questionable (see the Google paper for a discussion on the profound lack of correlation of SMART parameters with actual failure rates). But its there if you want it. > Or will you see only some bogus block devices which do not accept SMART > commands, do not return real drive identity, and present themselves as RAID0 > #1, RAID0 #2 etc. instead? The RAID will provide you an abstraction (e.g. a layer you have to walk through) to your disks. Seeing what composes the RAID is generally not hard, though you might need to write a quick and dirty parser for this. The block devices are not bogus. They are logical block devices. -- Joseph Landman, Ph.D Founder and CEO Scalable Informatics, Inc. email: landman@scalableinformatics.com web : http://scalableinformatics.com http://scalableinformatics.com/sicluster phone: +1 734 786 8423 x121 fax : +1 866 888 3112 cell : +1 734 612 4615