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Re: Talking about RAID - disks with same id




Joe Pfeiffer wrote:

> It's my understanding that PTUUID on a disk using an MBR corresponds to
> the UUID on a disk using a GPT, not to PARTUUID (I don't know what on an
> MBR-based disk would correspond to PARTUUID, if anything).

# blkid /dev/sdf1
/dev/sdf1: UUID="5427071b-25c8-fff8-476d-ff8c9852b714"
TYPE="linux_raid_member" PARTUUID="13e17ac7-01"
# blkid /dev/sdg1
/dev/sdg1: UUID="5427071b-25c8-fff8-476d-ff8c9852b714"
TYPE="linux_raid_member" PARTUUID="13e17ac7-01"

# blkid /dev/sdf
/dev/sdf: PTUUID="13e17ac7" PTTYPE="dos"
                  ^^^^^^^^
# blkid /dev/sdg
/dev/sdg: PTUUID="13e17ac7" PTTYPE="dos"
                  ^^^^^^^^

Correct and exactly this is the subject of my concern. What blkid is
reporting for the disk matches (correctly) to the PARTUUID - which as it
looks like tells us which partition it is.

I can't believe that this blkid library might be used in raid as if you read
the description it can easily report identical IDs.

Might be really worth examining the code - the last thing I wanted to do
now. Perhaps I ask on the kernel list.

thanks and regards