On Mon, Mar 23, 2009 at 6:02 PM, Jon Hardcastle <jd_hardcastle@xxxxxxxxx> wrote: > > I'd like to understand how you even go attaching that many devices to a system.. I am 'comparatively' new to this.. and have a 6 raid5 system.. not enterprise.. and i have slammed into case/power/sat slot issues already. What sort of hardware must one use to grow to a 36 array system! well, i am using a DAS in a JBOD mode. Cards are LSI logic Fiber channel. > ----------------------- > N: Jon Hardcastle > E: Jon@xxxxxxxxxxxxxxx > '..Be fearful when others are greedy, and be greedy when others are fearful.' > ----------------------- > > > --- On Mon, 23/3/09, Bill Davidsen <davidsen@xxxxxxx> wrote: > >> From: Bill Davidsen <davidsen@xxxxxxx> >> Subject: Re: How to configure 36 disks ? >> To: "Raz" <raziebe@xxxxxxxxx> >> Cc: linux-fsdevel@xxxxxxxxxxxxxxx, "Linux RAID Mailing List" <linux-raid@xxxxxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx, linux-aio@xxxxxxxxx, "linux-ide@xxxxxxxxxxxxxxx" <linux-ide@xxxxxxxxxxxxxxx> >> Date: Monday, 23 March, 2009, 3:35 PM >> Raz wrote: >> > Hello >> > I need to configure 3xDAS'es, each with 12 disks. >> > All three DAS'es are connected to a single >> machine. >> > I have the following requirements (in this order of >> importance) >> > from the storage: >> > >> > 1. redundancy. >> > having two disks failing in one raid5 breaks the >> entire raid. when >> > you have 30TB storage >> > it is a disaster. >> > >> > 2. performance. >> > My code eliminates Linux raid5/6 write penalty. I >> managed to do by >> > manipulating xfs and patching linux raid5 a bit. >> > >> > 3. modularity ( a "grow" and it will be nice >> to have "shrink" ) >> > file system and volume must be able to grow. >> shrinking is possible >> > by unifying multiple file systems >> > under unionfs or aufs. >> > >> > 4. Utilize storage size. >> > >> > I assume each disk is 1TB. >> > >> > >> ___ snip ___ >> >> > Any other ideas ? >> >> Yes, you have the whole solution rotated 90 degrees. >> Consider your original solution #2 below... You have no >> redundancy if one whole DAS box fails, which is certainly a >> possible failure mode. If you put the RAID0 horizontally, >> two arrays size six in each DAS, then RAID6 vertically, if >> one DAS fails completely you still have a functioning >> system, and the failure results for individual drives >> remains about the same, while the rebuild time will be >> longer. >> >> Solution #2 >> raid0 >> DAS1: raid6: D,D,D,D,D,D | >> raid6: D,D,D,D,D,D | >> | >> DAS2: raid6: D,D,D,D,D,D | xfs. >> raid6: D,D,D,D,D,D | >> | >> DAS3: raid6: D,D,D,D,D,D | >> raid6: D,D,D,D,D,D | >> >> >> In addition, you can expand this configuration by adding >> more DAS units. This addresses several of your goals. >> >> In practice, just to get faster rebuild as the array gets >> larger, I suspect you would find it was worth making the >> horizontal arrays RAID5 instead of RAID0, just to minimize >> time to full performance. >> >> -- bill davidsen <davidsen@xxxxxxx> >> CTO TMR Associates, Inc >> >> "You are disgraced professional losers. And by the >> way, give us our money back." >> - Representative Earl Pomeroy, Democrat of North Dakota >> on the A.I.G. executives who were paid bonuses after a >> federal bailout. >> >> >> -- >> To unsubscribe from this list: send the line >> "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at >> http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
