On Thu, Oct 21, 2010 at 08:59:13AM -0700, Nataraj wrote: > fred smith wrote: > > On Tue, Oct 19, 2010 at 07:34:19PM -0700, Nataraj wrote: > > > >> > >> I've seen this kind of thing happen when the autodetection stuff > >> misbehaves. I'm not sure why it does this or how to prevent it. Anyway, > >> to recover, I would use something like: > >> > >> mdadm --stop /dev/md125 > >> mdadm --stop /dev/md126 > >> > >> If for some reason the above commands fail, check and make sure it has > >> not automounted the file systems from md125 and md126. Hopefully this > >> won't happen. > >> > >> Then use: > >> mdadm /dev/md0 -a /dev/sdXX > >> To add back the drive which belongs in md0, and similar for md1. In > >> general, it won't let you add the wrong drive, but if you want to check use: > >> mdadm --examine /dev/sda1 | grep UUID > >> and so forth for all your drives and find the ones with the same UUID. > >> > > > > Well, I've already tried to use --fail and --remove on md125 and md126 > > but I'm told the members are still active. > > > > mdadm /dev/md126 --fail /dev/sdb1 --remove /dev/sdb1 > > mdadm /dev/md125 --fail /dev/sdb2 --remove /dev/sdb2 > > > You want to use --stop for the md125 and md126. Those are the raid > devices that are not correct. Once they are stopped, you can take the > drives from them and return them to md0 and md1 where they belong.! > > You will need to add the correct drive that was originally paired in > each raid set, but as I mentioned, it won't let you add the wrong > drives, so just try adding sdb1 to md0, then if it doesn't work, add it > to sdb1. You can't fail out drives from arrays that only have one drive. Thanks for the additional information. I'll try backing up everything this weekend then will take a stab at it. someone said earlier that the differing raid superblocks were probably the cause of the misassignment in the first place. but I have no clue how the superblocks could have become messed up, can any of you comment on that? willl I need to hack at that issue, too, before I can succeed? thanks again! > > Nataraj > > mdadm /dev/md126 --fail /dev/sdb1 --remove /dev/sdb1 > > mdadm: set /dev/sdb1 faulty in /dev/md126 > > > > > > mdadm: hot remove failed for /dev/sdb1: Device or resource busy > > > > with the intention of then re-adding them to md0 and md1. > > > > so I tried: > > > > mdadm /dev/md0 --fail /dev/sda1 --remove /dev/sda1 > > and got a similar message. > > > > at which point I knew I was in over my head. > > > > > >> When I create my Raid arrays, I always use the option --bitmap=internal. > >> With this option set, a bitmap is used to keep track of which pages on > >> the drive are out of date and then you only resync pages which need > >> updating instead of recopying the whole drive when this happens. In the > >> past I once added a bitmap to an existing raid1 array using something > >> like this. This may not be the exact command, but I know it can be done: > >> mdadm /dev/mdN --bitmap=internal > >> > >> Adding the bitmap is very worthwhile and saves time and risk of data > >> loss by not having to recopy the whole partition. > >> > >> Nataraj -- ---- Fred Smith -- fredex at fcshome.stoneham.ma.us ----------------------------- The Lord detests the way of the wicked but he loves those who pursue righteousness. ----------------------------- Proverbs 15:9 (niv) -----------------------------