persistent scsi with udev

persistent scsi with udev

[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 ?

Thanks
Andreas

Re: persistent scsi with udev

[James Smart]

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


Andreas Moroder wrote:
> 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
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: persistent scsi with udev

[Michael Reed]

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


James Smart wrote:
> 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
> 
> 
> Andreas Moroder wrote:
>> 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
>>
>> -
>> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: persistent scsi with udev

[Andreas Moroder]

Michael Reed schrieb:
> 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
> 
hello Mike,

we use SLES 10.
The direct path is THE solution.

Thanks
Andreas

Re: persistent scsi with udev

[Andreas Moroder]

James Smart schrieb:
> 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
> 
Hello James,

I know the emulex white paper, but it was a little bit unclear to me.

Thanks
Andreas

P.S.: Is Smart really your surname or does it only describe how you are ?