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SCA to Ultra2 conversion

Trish's Escape from Hardware Hell Help Board » Hardware » Hard Drive and Storage Related » SCA to Ultra2 conversion « Previous Next »

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Juan Martinez
Posted on Sunday, October 10, 1999 - 5:38 pm:   

I am trying to assemble a new computer w/scsi (first time). I have Adaptec AHA2940U2W controller and Seagate ST34520LC Medalist pro (LVD and SCA-2). The board refuses to recognize the drive. I have an adapter and the drive light comes on and it spins up. SO my question is how do I get my card to play nicely with my drive. DO I need to set the SCA adapter and the drive to the same ID or different ID's? Do single ended, motor delay, or motor start, or sync matter? (Sync is on the adapter, not the drive) Any insights would be appreciated. You can email me at Thanks
Posted on Sunday, October 10, 1999 - 8:35 pm:   

You must have an LVD compatible cable. Some older cables may not cut it in this respect. According to Seagate, you must also have an LVD terminator on the end of your SCSI cable. Set the drive to id 0. Leave the other jumpers at defaults. Hit ctrl+a when the scsi bios is booting and ensure that the card is set to id 7 (default), and leave everything else at defaults. Should work fine, assuming there is nothing wrong with the drive or the card.
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Juan Martinez
Posted on Sunday, October 10, 1999 - 9:34 pm:   

The cable I am using is a new cable which is purported to be compatible with LVD by the store I bought it from. I have set the drive ID to 0. It still didn't work. Do you know anyting of the SCA to scsi converter? Both the drive and the card are new. By the way, I have checked Seagate's site as well as Adaptec's and they both didn't offer much of a solution.
Juan Martinez
Posted on Monday, October 11, 1999 - 5:10 pm:   

By the way, the drive is SCAM compliant, the card is not at least not from what I have gleaned from adaptec's site.
Dave (Dave)
Posted on Friday, October 15, 1999 - 1:21 am:   

I've since learned that termination is required in order to make LVD work. It seems that the easiest thing to do is buy an LVD cable with a terminator . You can make do with a standard SCSI 3 cable and a terminator, but you won't be able to tell if your problems emerge from the cable or whatever. We have a number of LVD machines here, but my own area of expertise is with older stuff. The resistance required for LVD (low voltage differential)is unlike any termination that has come before it. The beauty of this system is that it is backwards compatible (unlike previous differential SCSI schemes). Which means that you can have a SCSI2, SCSIW, SCSIUW, and SCSI LVD on the same bus. The penalty is that the bus will only operate at the speed of the slowest device.
Get a terminator for your bus and you should be on your way to 80 MB/sec in no time...
Posted on Friday, October 22, 1999 - 11:17 am:   

A few things - I have the same adapter. It comes with a good U2 cable with a terminator built in.

With a BIOS update for the adapter, it WILL support SCAM.

The 2940U2W does not support SCA drives. These are mainly used in RAID configurations with special backplanes.

If you are using an 80 pin (SCA) to 68 pin adapter, Seagate told me that they STRONGLY reccomend against using this. No reason for this was given, sorry.

By the way - My adapter was giving me tons of problems at first. Everything looked like it was a termination problem. I downloaded the latest Adaptec BIOS update and the problems mysteriosly went away.

The latest version is 2.20.0 I believe.

Hope this helps.

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