I have a drive that has bad sectors. Lots of them. smartctl shows # 1 Short offline Completed: read failure 20% 530 1953520877 A simple ddrescue to this part of the disk gets this: Mar 16 10:41:28 elm kernel: [ 8643.123397] sd 3:0:0:0: [sdd] 1953525168 512-byte hardware sectors (1000205 MB) <snip<>51/40:00:f0:5c:70/00:00:74:00:00/e0 Emask 0x9 (media error) Mar 16 10:41:29 elm kernel: [ 8644.190060] ata4.00: status: { DRDY ERR } Mar 16 10:41:29 elm kernel: [ 8644.190099] ata4.00: error: { UNC } and reports 30 or so errors. mdstat tells me: md0 : active raid5 sdd1[0] sdb1[2] sda1[1] 1953519872 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU] So sdd1 is in there. /dev/sdd1 is the full disk Now this is an enterprise class disk so I thought re-writing the blocks would be worthwhile as a first step. (It is being RMAed but if it succeeds then I'll stop the array, mirror/replace the disk and start the array - less risky than a resync). However (two runs of) echo repair > /sys/block/md0/md/sync_action ran to completion without *any* errors being reported in syslog (or anywhere) Is this expected? It suggests that it isn't reading the bad parts of sdd. It certainly hasn't repaired it and I'm none the wiser... kernel is 2.6.26-1-xen-686 mdadm v2.6.7.2 PS This is an excellent place where I'd love to add in a new 'spare' disk, mirror sdd to the new disk (apart from the bad sectors which should come from the array) and then swap new for old. Instead I'm going to have to go degraded and sync - risking a sector read failure on one of the other drives and a restore from backup :( -- "Don't worry, you'll be fine; I saw it work in a cartoon once..." -- 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