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! ----------------------- 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
