I just discovered (the hard way, sigh, but not too much data loss) that a 4-drive RAID 10 array had the mirroring set up incorrectly. Given 4 drvies A, B, C and D, I had intended to mirror A<->C and B<->D, so that I could split the mirror and run on either (A,B) or (C,D). However, it turns out that the mirror pairs are A<->B and C<->D. So pulling both A and B off-line results in a non-functional array. So basically what I need to do is to decommission B and C, and rebuild the array with them swapped: A, C, B, D. Can someone tell me if the following incantation is correct? mdadm /dev/mdX -f /dev/B -r /dev/B mdadm /dev/mdX -f /dev/C -r /dev/C mdadm --zero-superblock /dev/B mdadm --zero-superblock /dev/C mdadm /dev/mdX -a /dev/C mdadm /dev/mdX -a /dev/B I'm assuming that fresh spares will be assigned to the lowest available slot. I just get nervous about commands with names like --zero-superblock when I have data I'd rather not lose. Thanks! - 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
