External SCSI question

[Om]

I've been using an external 50 pin Sanyo CDRW for a few years, and an internal 50pin SCSI HDD without any issues. Today I got an old external SCSI case and ripped out the old SyQuest drive that was in there and replaced it with the HDD I was using inside my case. Now the weirdness starts.

I can't boot my system with both drives connected externally. The system boots fine with either one, but not both. It hangs at 'Verifying DMA Pool' every time. I've tried terminating one then the other drive, no change. Putting them in different order on the chain, no change. Checked that they aren't using the same ID, my CDRW is at 6, HDD is at 2. Checked the Adapter card BIOS and it sees both devices.

Am I doing something wrong? Both work if one is internal and one external. Both work external separately just not together. I've never used two external devices before so maybe I'm totally missing something here?

 

[borealiss]

it may just be a case where you cannot use them together. sometimes the 50 pin converter where the centronics cable gets converted to standard 50 pin that the cdrw and the hard disk can use can introduce capacitance issues, depending on the quality of the converter for the external case. if this is the case, you might not be able to use the two together. other than that, i have no idea why you shouldn't be able to use them together since they were on the same scsi controller (?) channel before you had this problem.

 

[Om]

Yes both were connected to the same controller that was working fine before when one was internal and one external.
Well, it's not what I wanted to hear, but that could explain it, since nothing else seems to at this point. Thanks.

 

[cloudchief]

Cabling might be too long. It may have worked when it was inside because the cable lengths were just under maximum. When you put the hard drive in the external case, it went over the max. You can find a guide to cable lengths on Adaptec's site, I'm too tired to find it and link it for you.

 

[mastertech01]

Are you using an active terminator or just a drive terminator for buss termination. Sometimes you have to use a good hardware active terminator to get sufficient termination in external environment. Often built in termination is not sufficient for long cabling for what ever reason. This just from my past experience with it and long cables.

 

[Om]

I'm using active termination.
I've played around some more with this today and I've discovered a few more things that may help someone answer this:

I have 3 external SCSI I've been playing with, a scanner, CDRW and the HDD. (Only two cables) All 3 work fine by themselves.
When I chain the CDRW (1st) and the scanner (2nd) I can go into the controller BIOS and detect both, but the CDRW shows in ASSCI text, a numerial fraction, a few smiley faces, a arrow, etc. The scanner shows as itself. Then on boot up the CDRW isn't seen at all but the scanner is.
So now I know that the cabling is ok because the scanner is the second in the chain. It has active termination.

I use the same cable for the CDRW and HDD but I can't boot into windows at. I've tried switching positions on the cable but same results. Again last in chain has active termination. I can boot into windows if one of them is switched off, but both still connected to eachother, so I assume that means the converters for the external case is working ok as is the cables?

Hope this sheds a bit of light on this problem. It seems like everything Should work because each peice works on it's own, it simply won't work chained together which makes me think I'm doing something wrong?

 

[Workin']

Don't know if this helps but I had a similar problem with a CDRW, Jaz drive, and scanner on the external chain and a Zip drive on the internal - the CDRW would never work right. I figured out that if I took the scanner off the chain then everything worked fine. So I retired that scanner and got a USB one and now everything works great.

I'd suspect a termination or cabling problem.

 

[mastertech01]

Im using a 50 Pin Ultra controller for these slower devices. My scanner is first connected via a 25 pin to HD 50 cable to the controller, then my zip drive via 25 pin to 25 pin cable to the scanner, and last is my Jazz drive using centronix 50 at the Jaz external case to 25 pin on the zip drive. The Jazz in external case has a centronix 50 pin active terminator. ALL work fine like this.

 

[Om]

My choices are 25 pin from controller to 50 cable to either CDRW or HDD or scanner, then 50pin to the others. I'd need another 25pin cable to 50 pin if I wanted the scanner first)

This may sound weird, but is it possible that the CDRW doesn't like it's ID changed? The CDRW and scanner was set at the factory at ID6, so to use both one has to be changed. I changed the scanner to 5 and still have this problem. But, when I changed the CDRW to 5 (from 6) and tried to boot with it alone on the chain, it takes forever to get into windows? I'm talking three minutes hanging at boot! Once in windows all is normal, but the boot when the drive is at 6 by itself takes no time at all?

I guess I'm going to have to do some more reading on SCSI. The more I play with this the more odd it seems to me. Every peice of this puzzle works, separately, just not when they are all connected together. MasterTech01's works,...why not mine?

 

[DieHardware]

My ECS K7S5A/900 Athlon/Adaptec 2940AU/Syquest Syjet external-removable 1.5GB HDD/IBM internal 2.1GB HDD would hang after boot with my Umax 2200U scanner connected until I enabled LUN support(don't ask me why this should matter it just did).