BIOS assisted raid

Hi everybody,

my setup is a bit special.
My /boot is on a Transcend IDE Flash drive
My / is on partition of a Promise FastTrak 376 BIOS assisted mirror (dmraid)
My /home is on lvm2 volume based on a md raid5 volume

I chose this setup because the raid5 members come earlier in the bios than the mirror disks, thus it is not possible to boot from the mirror disks directly. Maybe it would have been better if I put the root filesystem on a lvm2 volume too.

This setup worked fine, when I installed opensuse 10. But since then I have problems when I upgrade to a newer version, and sometimes even when a new kernel comes out.
One problem is the initrd. Most of the time mkinitrd does not add the dmraid module. And the dmraid module calls dmraid -p which sets up the mirror device but not the partitions on it.
The other problem is the naming of the root device. Sometimes it is called pdc_cabefijghp1 and sometimes pdc_cabefijgh_part1.

Are these problems bugs, or is my setup too special, or plain wrong ?
Are there workarounds to make it run more reliable ?

All suggestions are greatly welcome.
Bernhard

There are known problems with any ‘fake raid’ which, AFAIK, is what you have, partly because Linux has its own commands for setting up RAID volumes. The advice I was given was only to use the Linux facilities.

Out of curiosity, at least to handle part of the problem:
What do you have in /etc/sysconfig/kernel under INITRD_MODULES="" ?
Is the dmraid explicitely mentioned there?

Hello tkdub,

“Fake-raid” as it is often called, “bios assisted raid”, etc., it’s a critter that is fairly well supported by the linux kernel. It is handled by dmraid.

I have used it successfully in the past. Please be aware the 11.3 MAY have shipped with a foobared udev which prevented the proper device nodes from being created. This problem certainly existed in the final release candidate, but may be fixed in the final 11.3 download image; I just don’t know.

My advice … make good backups and** test it!**

FYI … I did a little benchmarking recently … kernel raid (mdraid) is MUCH faster on my system (cheap adaptec fake-raid card vs. mdraid through ichX on mobo …

Best of luck and have fun!

oxala

oxala wrote:

> Please be aware the 11.3 MAY
> have shipped with a foobared udev which prevented the proper device
> nodes from being created. This problem certainly existed in the final
> release candidate, but may be fixed in the final 11.3 download image;
> I just don’t know.

It was fixed.


Per Jessen, Zürich (17.8°C)
http://en.opensuse.org/User:pjessen

Hello Per Jessen,

Thanks for the info!

Then fake-raid should work just fine!

oxala