Please forgive me if this shows up twice, I tried to send once but it has taken an improbable time and still not shown up, so it's time to try again. Following a premature (3 months) disk failure, I created a RAID 1 array. I understand the basic idea of RAID, but have never used the tools to do it before (not on Linux, not on anything). As I built it, I knew there were many things I didn't know about, but hoped I could learn slowly in "spare" time. For example: does RAID move bad blocks on it's elements, or does it just dump the doubtful device? If RAID finds a disk problem, does it tell me about it, and if so how? If RAID rejects a device, particularly if it's for "transient" reasons like a single bad sector, can I re-prepare the disk manually and get it back into service. If I have to replace a failed disk, how do I do that? Anyway, these questions are still unanswered (after about 3 months...) and guess what: I'm pretty sure I have a drive failure. It makes odd noises, like the other one did :( I poked around, and managed to work out the existance of the mdadm command, and found this: # mdadm --detail /dev/md0 /dev/md0: Version : 00.90.01 Creation Time : Thu Sep 1 05:49:50 2005 Raid Level : raid1 Array Size : 156280192 (149.04 GiB 160.03 GB) Device Size : 156280192 (149.04 GiB 160.03 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Sat Oct 8 09:38:25 2005 State : clean, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 0 Spare Devices : 0 UUID : b829bc95:3f42a40e:5a8be8f6:4fadb25c Events : 0.1345011 Number Major Minor RaidDevice State 0 0 0 - removed 1 34 1 1 active sync /dev/hdg1 I don't really know what I'm looking at, but the output looks bad, right? I also found this in dmesg's output: md: Autodetecting RAID arrays. md: autorun ... md: considering hdg1 ... md: adding hdg1 ... md: adding hde1 ... md: created md0 md: bind<hde1> md: bind<hdg1> md: running: <hdg1><hde1> md: kicking non-fresh hde1 from array! md: unbind<hde1> md: export_rdev(hde1) raid1: raid set md0 active with 1 out of 2 mirrors md: ... autorun DONE. Which also looks bad, don't you think? So, can anyone please tell me in the short term: 1) Is hde indeed out of the array as it appears? 2) How can I determine what the failure is? (is it "a few" bad sectors, too many to want to reuse the drive, or a more complete failure) 3) Can I reformat, move bad sectors, clean up the drive (if it's a minor failure) and get it back into service, and if so how? 4) If I elect/have to replace the drive, what do I do to make it take up it's ordained place in the md array? Then in the longer term, where should I be looking for the docs so I can know this for myself in future? Many thanks, Simon "You can tell whether a man is clever by his answers. You can tell whether a man is wise by his questions." Naguib Mahfouz __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com