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Let me ask a dumb SCSI question, but how can you get up to 15 devices.....

C

compuwiz1

Admin Emeritus Elite Member
When you have only 0-3 SCSI ID's??? I have a fourth drive I would love to install. 😀

I have a CDRW, DVD and 2 Cheetahs, and 1 IBM LVD already and I want to add back in my other IBM LVD, but I have installed the DVD taking the ID that the IBM used to occupy. This is probably dirt simple, but I don't build scsi stuff day in and day out. 🙁
 
Yes, I set the ID's on the drives. But, how can you get more than 4 drives? If any of them share the same ID, I get lockups.
 
how do you set the ids on your drives? Are they jumper blocks? Cant you have them on auto ID? I know my plextor drives do that.
 
hmm, my controller searches both channels for 15 ids. does yours have an auto search function? i technically can have 28 devices [2 are for controller]...
 
hmm, your scsi card should be id7, your boot drive id0, cd & cdrw ideally id 4 & 3.
your new hdd if it isn't a boot drive should get id1!
 
Auto...hehe, who would have figured? I'll look at it tomorrow. Someone who helped me set the system up originally told me I had to give them each their own ID. That would be fine with 3 or 4 drives. :Q <<<<I was really a computer newbie then.
 


<< Someone who helped me set the system up originally told me I had to give them each their own ID. >>


that's correct info!
 
Normal drives cannot share the same ID.

There is a sub-section of the SCSI standard that allows for the POSSIBILITY for drives to share IDs using LUN values (logical unit number), but most drives don't impliment LUN mapping.

A &quot;narrow&quot; SCSI device supports 8 channels (7 plus the controller) and &quot;wide&quot; SCSI supports 16 channels (15 + controller).

Why are you thinking you only have 4 IDs?? Do your drives only have that many? It is customary to put the drives on the lower numbers since the ID numbers are usually used for boot-priority and lower numbers usually have higher bus priority, but they will work fine on any channel provided they're not sharing.

Cheers,
Eric
 
To set IDs on drives normaly you use jumpers. Normaly you have 4 pairs of jumpers. The values of pairs 1 -4 are 1,2,4,8 respectivly. If you do not connect the jumpers they = 0 . So if you have jumper 1 closed and the rest open the ID of the drive is 1. If you have pairs 2 and 4 closed the ID of the drive is 10. If pairs 1,3,and4 closed it would be 13. So using the pins you can go from 0 to 15. Some older drives only had 3 pairs, so you could only go from 0 to 7. One ID (normaly 7) has to always be set aside for the controler.

Hope it helps
 
Just check the documentation from the manufacturer to find out the correct way to set the ID number. It's going to be a scheme exactly like Barrak says and there are some limits like Barrak and EricHagen pointed out.

You've got plenty of ID's left to install what you have and much more.

 
scroll down near the end of this page, to the 'scsi address settings' .. where it shows the jumper block.

you only have scsi address settings 0-3, *but* you have numerous different ways to jumpers those settings .. allowing you to set scsi IDs to anything from 0 to 15, including 8, 9, 10, 11, etc.

does that help?

no, you can't have any two devices sharing the same scsi id. that's a golden scsi rule.
 
Radboy, that will be helpfull. I am tearing down the system and going to upgrade the mobo soon. I have not been in there for many months, but I'm sure that info will help. 🙂

Thanks again!
 
Compuwiz, you are misreading the jumper section of your drive.
I know it is irritating, but what you see as ID 0 to ID 3 is NOT the correct jumper block. Check the IBM page for settings. You can set your ID from 0 to 15, with the exclusion of 7 which is the standard for the controller. The boot drive DOES NOT NEED TO BE ID 0! It is a common misstake. ID´s will be read in a certain way (read Gary´s SCSI FAQ) but the bootdrive is set as DRIVE 0 which is not the same as ID 0. You can have your Boot drive at ID 2 configured as DRIVE 0, the secondary as Drive 1 etc..
 
I've seen ppl have problems when trying to set their boot drive at a SCSI ID other than 0.

Like Rellik says, you should be able to boot from *any* SCSI (by setting it in the SCSI bios) .. 'should' is the key word in that sentence.

FWIW.

Glad to help. This might help, too.
 
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