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RAID card for external SCSI device

Paul Tsang
Occasional Visitor

RAID card for external SCSI device

Does RedHat linux support using RAID card for SCSI device?

The RAID BIOS can scan the device but cannot be used at /dev/st*

The machine I am using is in fact DL380g3 built in raid card.
1 REPLY
Stuart Browne
Honored Contributor

Re: RAID card for external SCSI device

The built in RAID controller on the DL380g3's is used as a 'cciss' isn't it?

If it is, then you might want to read the 'cciss.txt' file that comes with the Kernel source (in the kernel-doc package).

It states the following: (copy/paste)

+++
SCSI tape drive and medium changer support
------------------------------------------

SCSI sequential access devices and medium changer devices are supported and
appropriate device nodes are automatically created. (e.g. /dev/st0, /dev/st1, etc. See the "st" man page for more details.) You must enable "SCSI tape drive support for Smart Array 5xxx" and "SCSI support" in your kernel configuration to be able to use SCSI tape drives with your Smart Array 5xxx controller.

Additionally, note that the driver will not engage the SCSI core at init time. The driver must be directed to dynamically engage the SCSI core via the /proc filesystem entry which the "block" side of the driver creates as /proc/driver/cciss/cciss* at runtime. This is because at driver init time, the SCSI core may not yet be initialized (because the driver is a block driver) and attempting to register it with the SCSI core in such a case would cause a hang. This is best done via an initialization script (typically in /etc/init.d, but could vary depending on distibution).
For example:

for x in /proc/driver/cciss/cciss[0-9]*
do
echo "engage scsi" > $x
done

Once the SCSI core is engaged by the driver, it cannot be disengaged (except by unloading the driver, if it happens to be linked as a module.)

Note also that if no sequential access devices or medium changers are detected, the SCSI core will not be engaged by the action of the above script.
+++

Make of that what you will..

By default, the 'SCSI tape drive support for Smart Array 5xxx" is set to Yes.
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