On Mon, Apr 26, 2010 at 11:18:50AM -0700, Michael Evans wrote: > > However as long as you remember that currently raid10 cannot be grown > (*may have very very recently changed) you can use any of the layouts > you like (I tend to prefer the 'far' layout). > > mdadm --create ... --layout=(man mdadm) blockdev0 blockdev1 blockdev2 blockdev3 > > n2 == Creates almost the behavior you described; each stripe consists > of b0c0 b0c1 b1c0 b1c1 (blockXcopyY) > o2 == Data backup is in the next stripe: that is mirrored and rotated > stripes: b0c0 b1c0 b2c0 b3c0 // b3c1 b0c1 b1c1 b2c1 > f2 == The first half is like raid0; the second half is like the o2 > above, but over the entire first half. mnjae, the second part of a f2 layout is also laid out in a raid0 fashion. > More info on far from man 4 md > When 'far' replicas are chosen, the multiple copies of a given > chunk are laid out quite distant from each other. The first copy > of all data blocks will be striped across the early part of all > drives in RAID0 fashion, and then the next copy of all blocks will be > striped across a later section of all drives, always ensuring that all > copies of any given block are on different drives. > > The 'far' arrangement can give sequential read performance > equal to that of a RAID0 array, but at the cost of reduced write > performance. If you employ a file system (like ext3), then the elevator algorithm tends to eliminate the write performance hit. best regards keld -- 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
