[OT] Mixing SCSI drives on a bus
I have a SCSI bus installed on a machine. Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus I would like to add a Seagate ST39175LW to the same bus. Does anyone know if this would cause any problems? Are there any rules that should be followed when mixing SCSI types on the same bus? Should I even be doing this? Thanks, Ahbaid.
there are no problems that should be caused by mixing different vendor drives on the same bus. just be sure to check your jumpers so that the disks are identified as different scsi IDs. On Tue, 2003-04-15 at 13:58, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
Should I even be doing this?
Thanks,
Ahbaid.
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On Tuesday 15 April 2003 16:58 pm, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
What type of SCSI are these drives? I can't tell without the specs of the drives. What level of SCSI are they? In general, if they are 'like devices' that is, they all use the same type of cable and have the same speeds, there should be no problem. You can usually have up to 7 SCSI devices on a controller (bus) but mixing devices of different speeds may cause performance slow-downs.
Should I even be doing this?
Thanks,
Ahbaid.
-- +----------------------------------------------------------------------------+ + Bruce S. Marshall bmarsh@bmarsh.com Bellaire, MI 04/15/03 18:01 + +----------------------------------------------------------------------------+ "It is now proved beyond doubt that smoking is one of leading causes of statistics." - Fletcher Knebel
On Tue, Apr 15, 2003 at 06:03:51PM -0400, Bruce Marshall wrote:
On Tuesday 15 April 2003 16:58 pm, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
What type of SCSI are these drives? I can't tell without the specs of the drives. What level of SCSI are they?
In general, if they are 'like devices' that is, they all use the same type of cable and have the same speeds, there should be no problem.
You can usually have up to 7 SCSI devices on a controller (bus) but mixing devices of different speeds may cause performance slow-downs.
Just make sure you don't put the new drive in with a lower SCSI ID. -- Brad Shelton On Line Exchange http://ole.net Phone: 313-526-1111 Fax: 313-526-3333
Thanks for all the suggestions, I did try it, and the id was lower than the other drives, why does this matter? and the drives did not show up! Having seen your email I will retry it and set the id above the other drives. thanks Ahbaid Brad Shelton wrote:
On Tue, Apr 15, 2003 at 06:03:51PM -0400, Bruce Marshall wrote:
On Tuesday 15 April 2003 16:58 pm, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
What type of SCSI are these drives? I can't tell without the specs of the drives. What level of SCSI are they?
In general, if they are 'like devices' that is, they all use the same type of cable and have the same speeds, there should be no problem.
You can usually have up to 7 SCSI devices on a controller (bus) but mixing devices of different speeds may cause performance slow-downs.
Just make sure you don't put the new drive in with a lower SCSI ID.
On Wednesday 16 April 2003 3:24 am, Ahbaid Gaffoor wrote:
Thanks for all the suggestions,
I did try it, and the id was lower than the other drives, why does this matter?
Because Linux assigns its 'drive names' in the order of the ID's. sda, sdb, sdc, etc.
and the drives did not show up! Having seen your email I will retry it and set the id above the other drives.
thanks
Ahbaid
Brad Shelton wrote:
On Tue, Apr 15, 2003 at 06:03:51PM -0400, Bruce Marshall wrote:
On Tuesday 15 April 2003 16:58 pm, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
What type of SCSI are these drives? I can't tell without the specs of the drives. What level of SCSI are they?
In general, if they are 'like devices' that is, they all use the same type of cable and have the same speeds, there should be no problem.
You can usually have up to 7 SCSI devices on a controller (bus) but mixing devices of different speeds may cause performance slow-downs.
Just make sure you don't put the new drive in with a lower SCSI ID.
-- +----------------------------------------------------------------------------+ + Bruce S. Marshall bmarsh@bmarsh.com Bellaire, MI 04/16/03 10:03 + +----------------------------------------------------------------------------+ "Eat prune yogurt for that 'get up and go' feeling."
I may be wrong, but I think that the slowest SCSI machine (whatever it is) will determine the speed that the entire bus can run at. If this is not the case, please, someone, correct me. --doug At 15:58 04/15/2003 -0500, Ahbaid Gaffoor wrote:
I have a SCSI bus installed on a machine.
Right now it has Seagate ST34371W and Quantum XP34361WD drives on the bus
I would like to add a Seagate ST39175LW to the same bus.
Does anyone know if this would cause any problems?
Are there any rules that should be followed when mixing SCSI types on the same bus?
Should I even be doing this?
Thanks,
Ahbaid.
-- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com
Depends on how smart the SCSI controller is. At boot time a good SCSI controller wil determine the capabilities of each device connected on each bus and communicate with each device at their best speed. If you mix various speeds on a SCSI bus your average throughput/performance for that SCSI bus will be determined by how often each device is actually used. A good SCSI controller will also renegotiate for a Hot Swap event for each device. A dumb/cheap SCSI controller may determine the speeds of all the SCSI devices at boot time and run at the slowest speed to eleminate the need for more advanced capabilities and higher development costs. On a mission critical or high performance machine you'd want to have all the SCSI devices the same for maximum performance, ease of maintenance, etc. You'd also spend more for the best SCSI controller you can afford. Stan
How is Adaptec's support for Linux?
CWSIV
On Wed, 16 Apr 2003 08:22:17 -0500 Stan Glasoe
Depends on how smart the SCSI controller is. At boot time a good SCSI controller wil determine the capabilities of each device connected on each bus and communicate with each device at their best speed. If you mix various speeds on a SCSI bus your average throughput/performance for that SCSI bus will be determined by how often each device is actually used. A good SCSI controller will also renegotiate for a Hot Swap event for each device.
A dumb/cheap SCSI controller may determine the speeds of all the SCSI devices at boot time and run at the slowest speed to eleminate the need for more advanced capabilities and higher development costs.
On a mission critical or high performance machine you'd want to have all the SCSI devices the same for maximum performance, ease of maintenance, etc. You'd also spend more for the best SCSI controller you can afford.
Stan
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No recent experience with Adaptec. I've been working for other hardware manufacturers that had their own SCSI controllers which worked very well with Linux. AFAIK Adaptec cooperates very well with Linux developers. They've had very good products for many years. There have been several threads on the list concerning Adaptec drivers and SuSE versions and how to resolve the challenges... Stan On Wed April 16 2003 10:23 pm, Carl William Spitzer IV wrote:
How is Adaptec's support for Linux?
CWSIV
On Wed, 16 Apr 2003 08:22:17 -0500 Stan Glasoe
writes:
Depends on how smart the SCSI controller is. At boot time a good SCSI controller wil determine the capabilities of each device connected on each bus and communicate with each device at their best speed. If you mix various speeds on a SCSI bus your average throughput/performance for that SCSI bus will be determined by how often each device is actually used. A good SCSI controller will also renegotiate for a Hot Swap event for each device.
A dumb/cheap SCSI controller may determine the speeds of all the SCSI devices at boot time and run at the slowest speed to eleminate the need for more advanced capabilities and higher development costs.
On a mission critical or high performance machine you'd want to have all the SCSI devices the same for maximum performance, ease of maintenance, etc. You'd also spend more for the best SCSI controller you can afford.
Stan
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participants (8)
-
Ahbaid Gaffoor -
Brad Shelton -
Bruce Marshall -
Carl William Spitzer IV -
Doug McGarrett -
rich turner -
Stan Glasoe -
Stan Glasoe