On Sat, 2005-08-27 at 08:56 +1000, Neil Brown wrote: > On Friday August 26, strombrg@xxxxxxxxxxxxxxx wrote: > > > > I've been working on a RAID setup with dual RAID controllers and > > three expansion boxes - 48 disks in all, including data, parity and > > global spares. > > If there are 48 drives, why do your drive-numbers go up to 59? > Confusing but not important. Agreed. The hardware likes to do that. > Presumably these are 360G drives (or there abouts) and you are hoping > to use about 42 for data and the remaining 6 for redundancy. Around 380G. > I feel this a bit tight but could be workable. > > If you were using Linux-soft-raid, I would probably suggest 3 16-drive raid6 > arrays, possibly making 1 a 15 drive raid6 so there is one global spare. > However I gather you are using hardware RAID - do the controllers > support RAID6 ?? I'd feel better about RAID 6, but the hardware doesn't support it. > > Please be sure to use a fixed-pitch font when viewing the tables found > > below. BTW, if people weren't so terrified of HTML, I could just make a > > nice HTML table for easy reading without silly font requirements... > > You mean some mail readers use variable-width-fonts to display > text/plain? How broken! Heh. > > > > > > Does anyone have any comments on: > > > > 1) The sanity of these 10 disk RAID 5's? > > It depends on the drives. > If you are using you-only-get-what-you-pay-for-IDE-drives, then I > would say it is insane. > If you are using you-pay-for-the-quality SCSI drives, then you should > be fairly safe. They're SATA's. > > > > 2) The degree of loss of reliability incurred by moving 3 disks from > > global spare to data? > > That depends a bit on your warranty arrangements on the drives. If > it's next-day-replacement (Really, truly) then it is probably OK. If > it is 'send us the bad drive and we'll see what we can do', then I > would suggest thinking again. This'll be the next thing I ask the vendor. > > > > 3) The degree of loss of reliability incurred by moving 2 disks from > > global spare to data? > > > > Should be safe enough. > > However I don't understand why you have 4 9+1 arrays, and 1 X+1 for > varying X. Maybe 9+1 is the largest the controller will give you, so > you have to go to 5 arrays. > In that case, 4 8+1 arrays, 1 9+1 array, and 2 global spares would > seem a more sensible arrangement. I'm going to pitch this (or maybe 3 8+1's) to the owner of the equipment and the vendor. It was the vendor that suggested the 9+1's. - 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
