Hi Graham, I guess you couldn't find much about this as it has more to do with common sense than magic formulae. If you have 4k-sector drives, align everything at multiples of 4k, use filesystem-units of multiples of 4k. As I read and it also seems very logical from the ATA / SCSI point of view, a stripe size of 256k seems most straight forward. This is the largest amount of data (a.t.m.) that can be read or written with a single command to a disk. What should I say more? Well, block 63 is too oldschool, coming from the CHS-alignment of old disks. It doesn't make any sense nowadays. My suggestion: - use GPT partitioning (for safeness into the future) - align the first partition at block 64 - use a filesystem chunk size of at least 4k (depending on the data you want to store you might use even larger chunks) Hope it helps, Stefan Am 05.06.2010 22:51, schrieb Graham Mitchell: > I've spent the last couple of days doing some googling, and my goodle-fu > seems to have deserted me at the moment. > > I'm looking for some guides and/or words of wisdom on how to partition disks > with optimal alignment for RAID devices, and also the same for laying file > systems on those devices. I've just (re)created a 15 drive RAID 6 array, and > I've partitioned the disk, and I'm building the array on partition 1, which > I see starts at block 63 - I am guessing that this is non-optimal? Is there > a magic formula that can be used to work out what the optimal starting block > on the disk should be, so that we can avoid (or at least reduce) the > read/modify/write penalty on the physical drives? > > Is there also a magic formula for doing the same for file systems laid down > on a RAID device? I guess that this would depend on the type of superblock > used, since there seems to be different locations (start, end, start +4k) > for it. > > I've read thru the manual pages (shocking I know), and I can't see anything > mentioned in there, and there's certainly no --optimal-alignment option > there (any chance for next version - lol). > > Can someone point me in the direction of some reading about this please? > > Thanks. > > > Graham > > -- > 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
