persistent scsi with udev

Hello,

we have a big problem with scsi device mapping.

We have a LSI Megaraid controller and a qlogic HBA with a attached SAN

When we boot the machine without the SAN then the first disk on the MEGARAID becomes \dev\sda

When we boot with the SAN attached then the first disk in the san becomes \dev\sda and the system stop.

Is there a step by step tot availabe on how to configure the udev files when two SCSI devices are installed in one machine ?

Thanks
Andreas

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You can see if a white paper we put together, which includes information on tapes, can help you. There's also a small section on "boot from SAN" which talks about configuring udev in initrd for boot devices. Although the content references distros, it should be applicable to the kernel generically.
http://www.emulex.com/white/hba/wp_linux26udev.pdf

-- james s

Quoted 15 lines · Andreas Moroder

Hello,

we have a big problem with scsi device mapping.

We have a LSI Megaraid controller and a qlogic HBA with a attached SAN

When we boot the machine without the SAN then the first disk on the MEGARAID becomes \dev\sda

When we boot with the SAN attached then the first disk in the san becomes \dev\sda and the system stop.

Is there a step by step tot availabe on how to configure the udev files when two SCSI devices are installed in one machine ?

Quoted 8 lines

Thanks
Andreas

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While you didn't explicitly mention which distro you're using, some already have udev in their initrd. If this applies in your case, you should be able to change the root= parameter passed to the kernel to specify your root device via a persistent name. For example:

	root=/dev/disk/by-path/pci-0000:01:03.0-scsi-0:0:1:0p1

You can do the same in your /etc/fstab for the root device.

You can ALSO change the order in which modules are loaded via /etc/modprobe.conf, or /etc/sysconfig/kernel, or something similar for your distro, so that the driver for your root device is always loaded first.

I hope this helps.

Mike

You can see if a white paper we put together, which includes information on tapes, can help you. There's also a small section on "boot from SAN" which talks about configuring udev in initrd for boot devices. Although the content references distros, it should be applicable to the kernel generically.
http://www.emulex.com/white/hba/wp_linux26udev.pdf