On Sun, 23 Mar 2008, Michael Hannon wrote:

> Greetings.  We've got an Opteron-based system running SL 5.1.  The
> system has an areca RAID controller that we're using in JBOD mode.
>
> This isn't a question about RAID, but as background information the
> system is set up to have four software-RAID devices, mounted as follows:
>
>    /dev/md1                /
>    /dev/md0                /boot
>    /dev/md2                /home
>    /dev/md3                /backup
>
> md0 and md1 are made up from partitions on two drives connected directly
> to the motherboard.  md2 an md3 are both formed from drives connected to
> the RAID controller.
>
> Everything seems to work fine, except that the system "forgets" the
> device md2 after a reboot.  I.e., /dev/md2 is simply not in whatever the
> system uses as a database for devices.
>
> Note that the system for some reason "remembers" md3, and that md2 and
> md3 are connected to the same controller.
>
> The workaround that we've used is to remove the reference to /dev/md2
> from /etc/fstab and then after rebooting:
>
>    a. force the creation of the device md2:
>               cd /dev
>               ./MAKEDEV -xv /dev/md2
>
>    b. assemble the RAID array:
>               mdadm /dev/md2 --assemble --scan
>
>    c. mount /dev/md2 "by hand"
>
> This is straightforward enough, and it could easily be automated, but
> there must be some way to make /dev/md2 permanent.  I don't recall that
> we had to do anything special for /dev/md3 (again, coming from the same
> controller).
>
> Please let me know if you have some way to fix this.

Probably...
1) check for "alias scsi_hostadapter arcmsr" in /etc/modprobe.conf;
2) chech for "Persistence : Superblock is persistent" in the output
  of "mdadm --detail /dev/md2";
3) after "mount /dev/md2 /home", do:
  mkinitrd -v -f /boot/initrd-2.6.18-53.1.14.el5.img 2.6.18-53.1.14.el5
4) dmesg | grep -E '^(md|raid)'
  after the next boot.

>
> Thanks.
>
> 					- Mike
> -- 
> Michael Hannon            mailto:[log in to unmask]
> Dept. of Physics          530.752.4966
> University of California  530.752.4717 FAX
> Davis, CA 95616-8677
>

Best regards,
  Valery Mitsyn