SCSI Drive help!!!

[Asphix20]

Hey, I need a quick response on this one. To make a long story short, I'm sort of an intern here at my local government helping out with the local access TV station. We are running a Dell workstation with 2 73 gig scsi drives. We were running out of space (we do video editing on it so need lots of space) and ordered a new drive(same drive)from Dell. I got the drive and installed it, but while installing it i bent one of the pins on the scsi cable. Now the system isnt recognizing any drives even when i keep only the original 2.

So, my question is... would bending the pin on one of thse prevent the system from detecting the hard drives? And also, if I need to run to the IT and have him purchase a new cable for us, the one we have now has a "terminator" on the end of it. Could someone please explain to me what a terminator is and what it does?

Thanks!

 

[Harvey]

1. If the pin is not so bent that you can't straighten it without breaking it (or feeling like it's cracked and ready to break), you MAY get awat with straightening it.

2. Terminators (other than Arnold) contain specific resistor values required at that end of the cable. They prevent signal reflections back along the cable that can appear as interference with the data signals and cause errors.

 

[Fallen Kell]

Ok... Long and short of it:

SCSI needs to be terminated. The bus itself is left unterminated because you can "chain" deviced onto it (kinda like a serial series in electronics). The terminator is required to keep the signals from bouncing back and causing feedback on the lines. You place the terminator at the end of the chain (i.e. either at the end of the last device or using a terminated cable).

The bent pin is most likely your problem, as it may either be shorting otherwise causing an issue. A new cable would most likely fix your problem. But, you are correct in that you need a cable that has a terminator on the end.

 

[Asphix20]

Thanks for the responses. the IT guy found an old scsi cable from 10 years ago and when I tried it it worked and the computer booted fine. I took that opportunity to do some surgery on the broken cable. I poped off the plug housing the bent pin and it looks like it got bent so badly that it skipped over from the pin1 stripe and was making a connection both there and in the next one over (you were right.. creating a short). For the time being we only need 3 devices and its working fine right now.. just copied a 20 gig file from one drive to the other without a problem. I covered the area of cable where the plug used to be with electrical tape just to be safe.. anything else i should watch out for?

 

[Fallen Kell]

Not really anything else to SCSI... aside from setting SCSI ID's on the devices. A good tip/rule of thumb that we use is that we set the ID backwards from the top ID available. We do this because it has only newer model devices that use the ID's 8-15, as the origional devices were only numbered 0-7. Many legacy devices can only be set to 0-7. So by going backwards from the top, we keep all new devices using the ID space that only the newer devices can use, and reserve the lower numbers for items that are legacy. Now this is not how you have to do this, but since we have a large install/storage base of older devices, it makes sense where I work.

Edit: Forgot to mention that the SCSI ID's need to be unique to each device on the chain/SCSI controller. Basically think of it like this, you can not have 2 masters on the same ide controller. Now its not "exactly" like that, but you will get similar problems (i.e. no devices detected, etc), if two devices have the same SCSI ID.