on 6-11-2008 10:41 AM Les Mikesell spake the following: > Ross S. W. Walker wrote: >> >>>>>> If you have a disk with several partitions set up as members of a >>>>>> raid1 md devices, can you make a dd image of that disk to replace >>>>>> its matching drive with identical partitions or are there >>>>>> differences between the mirrored partitions? >>>>> you can 'dd' the MBR and then re-add the partitions to the raid for >>>>> resyncing with 'mdadm'. >>>>> >>>>> # dd if=/dev/sda of=/dev/sdb bs=512 count=1 >>>>> # mdadm /dev/md0 --add /dev/sdb1 >>>>> # mdadm /dev/md1 --add /dev/sdb2 >>>>> >>>>> If you want to really make sure you got everything you could dd the >>>>> whole first track with: >>>>> >>>>> # dd if=/dev/sda of=/dev/sdb bs=512 count=63 >>>>> >>>>> -Ross >>>>> >>>> Or sfdisk -d /dev/sdX | sfdisk /dev/sdY >>>> where x is source and y is the target. >>>> This will work across drives that have slight geometry differences. >>> What I was hoping to do was to take the grub setup, the partitioning >>> info and the contents in one shot and have the disks pair >>> automatically when booted. They didn't - but I think the other parts >>> worked. >>> >>> Now, is there a way to change the uuid on a running raid1 set? I'd >>> prefer that if the split and re-paired disks ever find their way back >>> to the same machine that they not sync again. >> >> 'mdadm' writes a listing of the devices in the array to the md >> superblock and orders them by number,major,minor. You cannot add >> another device to the array with the same tuple. > > Isn't this updated at detect time so the device minor's should always be > different? > >> If you dd the first sector of the drive though you will duplicate >> the partition table and grub boot loader to the other drive. Then >> md-device-mapper will take care of copying the data over. > > 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)? -- 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/20080611/6412bd1a/attachment-0005.sig>