need help with RAID1 EFI GPT disks

[George Toft]

ok then . . . copying my backup back to a disk . . . this is a 26 hour 
evolution - back in a couple days :)

Regards,

George Toft

On 2/4/2014 6:04 PM, Michael Butash wrote:
> Looks like under knoppix it's not finding the disks you seek in at 
> least the right order, or all the partitions you're expecting:
>
> On 02/04/2014 11:00 AM, George Toft wrote:
>> Disk /dev/sda: 640.1 GB, 640135028736 bytes
>> /dev/sda1   *           1          64      512000   83  Linux
>> /dev/sda2              64       77826   624618496   8e  Linux LVM
>> Disk /dev/sdb: 3000.6 GB, 3000591900160 bytes
>> /dev/sdb1               1      267350  2147483647+  ee  GPT
>> Disk /dev/sdc: 3000.6 GB, 3000591900160 bytes
>> /dev/sdc1               1      267350  2147483647+  ee  GPT
>> [root at localhost ~]# 
>
> It's not finding the partitions for the data, or the disk as you're 
> trying to use parted to print or manipulate the data with mdraid.
>
> [root at localhost ~]# mdadm --assemble --scan
> mdadm: No arrays found in config file or automatically
> #
> ## it's not finding partition type fd for linux auto raid to start 
> automagically
>
> [root at localhost ~]# mdadm --create /dev/md0 -n2 -l1 /dev/sdb3 missing
> mdadm: cannot open /dev/sdb3: No such file or directory
> [root at localhost ~]# mdadm --create /dev/md0 -n2 -l1 /dev/sdc3 missing
> mdadm: cannot open /dev/sdc3: No such file or directory
> #
> ## none of these are present per above
>
> [root at localhost ~]# mdadm --create /dev/md0 -n2 -l1 /dev/sdb1 missing
> mdadm: cannot open /dev/sdb1: No such file or directory
> #
> ## this looks like you made the disk disappear from above, confirm 
> with the lsblk what is there at the moment...
>
> [root at localhost ~]# mdadm --create /dev/md0 -n2 -l1 /dev/sdc1 missing
> mdadm: /dev/sdc1 appears to contain an ext2fs file system
>     size=204800K  mtime=Sun Dec 29 10:32:43 2013
> mdadm: Note: this array has metadata at the start and
>     may not be suitable as a boot device.  If you plan to
>     store '/boot' on this device please ensure that
>     your boot-loader understands md/v1.x metadata, or use
>     --metadata=0.90
> Continue creating array? y
> mdadm: Defaulting to version 1.2 metadata
> mdadm: array /dev/md0 started.
> #
> ## hmm, you just initialized that with a superblock for mdraid, 
> probably nuking your ext2 boot partition here...
>
> [root at localhost ~]# mount /dev/md0 /mnt/raid
> mount: you must specify the filesystem type
> [root at localhost ~]# mount -t ext4 /dev/md0 /mnt/raid
> mount: wrong fs type, bad option, bad superblock on /dev/md0,
>        missing codepage or helper program, or other error
>        In some cases useful info is found in syslog - try
>        dmesg | tail  or so
> #
> ## you haven't created a file system on this mdraid volume at sdc1, 
> use mkfs.ext4 for this on /dev/md0 first, as it needs a fs of some 
> flavour...
>
> It seems like I may be able to mount /dev/sdc3 if I can correct the size.
> Thoughts?
> #
> ## unfortunately it looks like you might have nuked the data, or it 
> was nuked with the reboot originally on that disk as the partition is 
> still simply not showing up on it, now neither side of the disk seems 
> present.  If it doesn't see partition 3 in any kind of block/partition 
> descriptor, it simply isn't there...
>
> Really, you need to be super-careful with these as depending on the 
> kernel or setup of udev, it tends to probe these out of order between 
> boots.  You always want to either validate it by it's UUID (using "ls 
> -la /dev/disk/by-uuid/), or verifying with hdparm -i as well the 
> devices for which disk is what.  The metadata version mdraid is using 
> is relevant as old versions are not forward compatible, and depending 
> on dist they may not be able to interpret what you have/had.  Fact 
> it's creating them at 1.2 metadata descriptors for the superblock, it 
> *should* be able to read the old .90 or .92 blocks, but I'm almost 
> thinking the disk is either damaged, or somewhere along these 
> adventures you inadvertently nuked the partitions.
>
> If you're not seeing the raided partition anymore, it's gone, but I 
> think your bigger issue is the old sdb disk is toast beyond just the 
> partitions.
>
> -mb
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