[CentOS] Re: raid1 disk format?

Les Mikesell lesmikesell at gmail.com
Tue Jun 10 18:20:13 UTC 2008

Scott Silva 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.

   Les Mikesell
    lesmikesell at gmail.com

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