problem with Megaraid + Adaptec and device names
bgibson at wheatonma.edu
Thu Aug 15 08:54:00 CDT 2002
We have a brand new Dell Poweredge 2550 with an onboard 2 channel
Adaptec SCSI card (7890 I believe) and a PCI MegaRaid card. The Megaraid
card has 2 channels and off of channel A there is a mirrored set. When
we install RedHat to the partitions on the mirrored set everything works
fine, that set is considered /dev/sda.
We have 2 external raid enclosures from a company called Zzyzx that we
want to connect to the on board Adaptec card so we purchased a PCI slot
cover that has a SCSI interface and a cable that connectes to the
internal channel A on the SCSI card. When we boot up the system, the
Adaptec card recognizes the device(s) at bootup and starts loading linux
from the MegaRaid card just like before. The problem is the boot up
hangs about halfway through because one of the external RAID enclosures
becomes /dev/sda and the mirrored drives that are off the MegaRaid card
end up beconing /dev/sdc
This is what I have tried.....
1. Installing an Adaptect 2940 PCI card and running those external
drives off of it (still no luck).
2. Moving the Adaptec 2940 PCI card up above and below the MegaRaid card
thinking that it might change the order in which the drivers come up
(still no luck).
3. Finding the megaraid driver in /etc/modules.conf and moving its
placement around in that file (still no luck).
4. Fooled around with the "map-drive" option in /etc/lilo.conf (still
5. The BIOS is disabled on both of the Adaptect cards (but that
shouldn't mattter since it does initially boot from the MegaRaid
6. I tried using Dell's Server Assistant CD to facilitate the RedHat
7.2 install (still no luck).
There are two ways we can get around this and one is somewhat acceptable
and the other is not recommended and I believe we take a performance hit.
1. We bought a mini-centronics scsi cable and can run external SCSI
devices off of channel B on the MegaRaid card externally, they do come
up as /dev/sdb and /dev/sdc (this was tested with a few cheap older
external drives, not with the external RAID arrays.... Zzyzx says that
they do not recommend this and will not support it because you are
doubling up on the RAID.)
2. We could install the OS with the two external Raid Arrays attached
and they can become /dev/sda and /dev/sdb but.... if one of those fails
at any point you have lost the OS.
Any help on this issue would be greatly appreciated.
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