on 6-12-2008 10:28 AM Les Mikesell spake the following: > Scott Silva wrote: >>> >>>>> >>>>> I'm curious as to why 2 complete dd'd copies don't pair at boot. >>>>> One comes up running and it does work to mdadm --add the partner >>>>> partitions and after the resync they do automatically pair at boot. >>>>> >>>> Are they dd copies of the different nodes (IE.. dd copy of sda >>>> paired with dd copy of sdb)? >>> >>> No - what was sda was dd'd twice with the dups put in sda and sdb. >>> >> That is why it didn't work. The superblock knows which drive it was >> on, and knows if there are dupes. > > But I thought the locations were re-detected at boot/assembly time. > > The other question is whether it is possible to change the uuid while > the system is running or if it would have to be done from a CD boot. > I've cloned several machines from one initial setup and if copies of the > disks ever find their way back into one box I'd prefer not to have the > wrong set try to re-sync. > The locations can re-detect, but I still think it will stop if it detects 2 identical superblocks. I don't think you can change the UUID of a running array, and I'm not sure if you can do it easily on a stopped array. I think the safest thing is to use the --add to join the pair. Since they are dd clones, the sync should be fairly fast. Just be careful. I know that it seems like an easy way to clone machines, but I think there are better and safer ways to clone machines. -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!! -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 258 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20080612/f7922a52/attachment-0005.sig>