[Fedora-sparc] Interesting problem with MD array creation

Patrick Ale patrick.ale at gmail.com
Wed Mar 17 09:52:53 UTC 2010


Hi,

I have an interesting challenge, maybe one of you can help me :-)

I am creating an MD RAID 1 array consisting out of two SATA disks
(currently /dev/sdb1 and /dev/sdc1).
Both partitions use the Sun disk label and the partitions used start
on cylinder 1.

   Device Flag    Start       End    Blocks   Id  System
/dev/sdb1             1     60788 488271577+  fd  Linux raid autodetect

  Device Flag    Start       End    Blocks   Id  System
/dev/sdc1             1     60788 488271577+  fd  Linux raid autodetect


When I run the mdadm command to construct the array (mdadm --create
/dev/md0 --level=1 --raid-devices=2 --run /dev/sdb1 /dev/sdc1) all
goes fine, the array syncs up and all.

However, when you do a blkid -c /dev/null you'll see that both
/dev/sdb1 and /dev/sdc1 both share the same UUID.

/dev/sdb1: UUID="978635d6-52ab-c92b-76ea-5a12e49bd4b5" TYPE="linux_raid_member"
/dev/sdc1: UUID="978635d6-52ab-c92b-76ea-5a12e49bd4b5" TYPE="linux_raid_member"

This is a big problem since after a reboot it might be that /dev/sdb
becomes /dev/sda and /dev/sdc becomes /dev/sda (this actually happens,
both on x86 and sparc).
With other words, without having unique UUIDs there is no way you can
construct a proper /etc/mdadm.conf file and start the array
automaticly on every boot.


Any ideas on a work around?


Thanks,


Patrick


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