Can I define SCSI device order?

Can I define SCSI device order?

[Paul Furness]

Good morning everyone.

I'm building a new system. It's a Dell Poweredge 2650 which has an
embedded SCSI controller with 2 HDD's attached. It also has in it an
Adaptec 39160 PCI card, which I want to use for external SCSI devices.


The plan is: Build the system (installing RedHat 7.3 + patches), and
then plug in the external RAID array which presents itself as a single
SCSI device.

The problem is that when I plug in the external array, it takes over as
"sda", shunting the disk with linux on it up to "sdb". This means that
it can't find the root partition, so although it starts booting from the
right place, it then kernel panics.

I _could_ change the configuration of grub and also fstab so that the
system boots happily from sdb, but then it is a problem if I remove the
disk array. Since there will be a backup system with exactly the same
hardware but no array, I need to be able to plug in the array and boot
the system without any messing around changing grub and fstab.

I investigated the PCI assignments of the SCSI controllers, and it shows
that the external one has PCI address 1:08.0 and 1:08.1, while the
internal one has 5:06.0 and 5:06.1. There are three PCI slots I can use
for the external card, and they come up as 0:xx.x, 1:xx.x and 2:xx.x, so
there is no way to get the internal SCSI controller to appear earlier on
the PCI bus than the external one.


So the question is: can I stop the external array taking over sda?  

Any ideas, anyone?

Paul.




-- 
Paul Furness

Systems Manager
Visual Information Lab
Mitsubsihi Electric ITE BV
Guildford, UK

Steepness is an illusion caused by flat things leaning over.

Re: Can I define SCSI device order?

[Scott Taylor]

At 04:52 AM 3/10/03, Paul Furness wrote:
>Good morning everyone.
>
>I'm building a new system. It's a Dell Poweredge 2650 which has an
>embedded SCSI controller with 2 HDD's attached. It also has in it an
>Adaptec 39160 PCI card, which I want to use for external SCSI devices.
>
>
>The plan is: Build the system (installing RedHat 7.3 + patches), and
>then plug in the external RAID array which presents itself as a single
>SCSI device.
>
>The problem is that when I plug in the external array, it takes over as
>"sda", shunting the disk with linux on it up to "sdb". This means that
>it can't find the root partition, so although it starts booting from the
>right place, it then kernel panics.
>
>I _could_ change the configuration of grub and also fstab so that the
>system boots happily from sdb, but then it is a problem if I remove the
>disk array. Since there will be a backup system with exactly the same
>hardware but no array, I need to be able to plug in the array and boot
>the system without any messing around changing grub and fstab.
>
>I investigated the PCI assignments of the SCSI controllers, and it shows
>that the external one has PCI address 1:08.0 and 1:08.1, while the
>internal one has 5:06.0 and 5:06.1. There are three PCI slots I can use
>for the external card, and they come up as 0:xx.x, 1:xx.x and 2:xx.x, so
>there is no way to get the internal SCSI controller to appear earlier on
>the PCI bus than the external one.

Internal/External SCSI controllers?  Do you mean one is built onto the 
Motherboard?

I think you need to ask your hardware manufacturer this one, it may be as 
simple as a jumper.  Personally, if I add PCI controllers to a motherboard 
I usually disable any on-board ones.  Better yet, don't buy motherboards 
with on-board SCSI.  If you must have two SCSI controllers then make them 
both add-on cards.

Scott.

Re: Can I define SCSI device order?

[Paul Furness]

Absolutely. The "internal" controller is an embedded one on the
motherboard. I'm calling it "internal" because it's being used to
control the hard disks which are inside the box. The "external"
controller is a normal, PCI card. I'm calling it "external" here because
it it being used to drive a disk array which is in a different box. 

I don't have any option to change the settings of the motherboard; I can
indeed disable the embedded controller, but that means I'll need to go
and buy another controller. 


<sigh> Just once I'd love something important to also be easy. :)


On Mon, 2003-03-10 at 15:59, Scott Taylor wrote:

> Internal/External SCSI controllers?  Do you mean one is built onto the 
> Motherboard?
> 
> I think you need to ask your hardware manufacturer this one, it may be as 
> simple as a jumper.  Personally, if I add PCI controllers to a motherboard 
> I usually disable any on-board ones.  Better yet, don't buy motherboards 
> with on-board SCSI.  If you must have two SCSI controllers then make them 
> both add-on cards.
> 
> Scott.
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-admin" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
Paul Furness

Systems Manager
Visual Information Lab
Mitsubsihi Electric ITE BV
Guildford, UK

Steepness is an illusion caused by flat things leaning over.

Re: Can I define SCSI device order?

[Scott Taylor]

At 08:42 AM 3/10/03, Paul Furness wrote:

>I don't have any option to change the settings of the motherboard; I can
>indeed disable the embedded controller, but that means I'll need to go
>and buy another controller.

There, you just answered your own question.  ;)

Re: Can I define SCSI device order?

[Scott Taylor]

At 08:42 AM 3/10/03, Paul Furness wrote:

><sigh> Just once I'd love something important to also be easy. :)

Nothing important is easy.  Kinda like posting replies chronologically.

Re: Can I define SCSI device order?

[James Goodwin]

Doesn't your Adaptec Card have both internal and external connections? 
 If so, you can just plug your HD's onto the Internal connection and the 
RAID to the port and make sure your termination is at the END's of the 
chain (not the card).  You'll also need to make sure the SCSI ID's of 
the drives are different (I don't remember which one needs to be higher).

Regards,
James

Paul Furness wrote:

>Absolutely. The "internal" controller is an embedded one on the
>motherboard. I'm calling it "internal" because it's being used to
>control the hard disks which are inside the box. The "external"
>controller is a normal, PCI card. I'm calling it "external" here because
>it it being used to drive a disk array which is in a different box. 
>
>I don't have any option to change the settings of the motherboard; I can
>indeed disable the embedded controller, but that means I'll need to go
>and buy another controller. 
>
>
><sigh> Just once I'd love something important to also be easy. :)
>
>
>On Mon, 2003-03-10 at 15:59, Scott Taylor wrote:
>
>  
>
>>Internal/External SCSI controllers?  Do you mean one is built onto the 
>>Motherboard?
>>
>>I think you need to ask your hardware manufacturer this one, it may be as 
>>simple as a jumper.  Personally, if I add PCI controllers to a motherboard 
>>I usually disable any on-board ones.  Better yet, don't buy motherboards 
>>with on-board SCSI.  If you must have two SCSI controllers then make them 
>>both add-on cards.
>>
>>Scott.
>>
>>-
>>To unsubscribe from this list: send the line "unsubscribe linux-admin" in
>>the body of a message to majordomo@vger.kernel.org
>>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>    
>>

Re: Can I define SCSI device order?

[Paul Furness]

Yeah, I could do that, but it is more than just an issue of making sure
everything is connected; more devices on a single bus = less bandwidth
for each disk. I'm building this for speed.

It's not really that bigger deal, I just wanted to try and make it as
foolproof as possible so that if our main system failed, I (or anyone
else) could plug the RAID array into the backup system and simply boot
it up and have it work. Instead, there's some reconfiguring needed,
which in turn means I have to write more instructions for people to
follow. But not many, though. :)

Paul.


On Tue, 2003-03-11 at 02:07, James Goodwin wrote:
> Doesn't your Adaptec Card have both internal and external connections? 
>  If so, you can just plug your HD's onto the Internal connection and the 
> RAID to the port and make sure your termination is at the END's of the 
> chain (not the card).  You'll also need to make sure the SCSI ID's of 
> the drives are different (I don't remember which one needs to be higher).
> 
> Regards,
> James
> 
> Paul Furness wrote:
> 
> >Absolutely. The "internal" controller is an embedded one on the
> >motherboard. I'm calling it "internal" because it's being used to
> >control the hard disks which are inside the box. The "external"
> >controller is a normal, PCI card. I'm calling it "external" here because
> >it it being used to drive a disk array which is in a different box. 
> >
> >I don't have any option to change the settings of the motherboard; I can
> >indeed disable the embedded controller, but that means I'll need to go
> >and buy another controller. 
> >
> >
> ><sigh> Just once I'd love something important to also be easy. :)
> >
> >
> >On Mon, 2003-03-10 at 15:59, Scott Taylor wrote:
> >
> >  
> >
> >>Internal/External SCSI controllers?  Do you mean one is built onto the 
> >>Motherboard?
> >>
> >>I think you need to ask your hardware manufacturer this one, it may be as 
> >>simple as a jumper.  Personally, if I add PCI controllers to a motherboard 
> >>I usually disable any on-board ones.  Better yet, don't buy motherboards 
> >>with on-board SCSI.  If you must have two SCSI controllers then make them 
> >>both add-on cards.
> >>
> >>Scott.
> >>
> >>-
> >>To unsubscribe from this list: send the line "unsubscribe linux-admin" 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-admin" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
Paul Furness

Systems Manager
Visual Information Lab
Mitsubsihi Electric ITE BV
Guildford, UK

Steepness is an illusion caused by flat things leaning over.