Slow SCSI HD

[HO]

I have a Quantum Fireball ST 3.2 gig Ultra SCSI 3 drive connected to an AdvanceSys ASB 3940ua Ultra SCSI adaptor. I should be seeing sustained throughput in the neighborhood of 6-8 Mbs. Instead I am seeing 4Mbs burst rates as measured by HD Tach. The HD is daisy chained to a Zip drive (tried removing the Zip, no change), and is the last device on the chain. Termination is enabled on the drive. Externally, an HP 4c scanner is the only thing going.

Can I get more speed out of my HD?

 

[HO]

Hello? Any SCSI gurus out there?

 

[Zach]

It's an old drive. What RPM is that thing? Are you sure it's Ultra SCSI 3? Isn't that Ultra160? I don't know the actual names anymore, I know UUltra, UW, LVD 80MB/s, Ultra 160 (another LVD).

 

[HO]

It's a 5400rpm drive. The SCSI 3 is old nomanclature, but I think it's equal to a fast SCSI 2, which is narrow, not wide. Regular SCSI is 8 bit, I think both the drive and controller are 16 bit. The thing that makes me think there's a bottleneck somewhere is that I have an even older Quantum Fireball 1.2 EIDE that is faster than the SCSI.

 

[Zach]

Check the dates if you can, that might have been a huge premo drive at one time; but maybe it predates the smaller IDE drive enough to justify the performane.

I'm thinking along these lines because I had an old Atlas II 9.1GB 7200RPM drive that barely gave me 9mb/s, a first generation Seagate Barricuda did about the same.

 

[esung]

Your drive should be a Ultra SCSI-2, not SCSI3.. I have 2 of the same drive. It's okay. It performs about the same of the IDE drive back then.. (that's the reason quantum phase them out so quickly and so cheaply). maybe a tad faster. If you have the scanner connected, to your SCSI card, try to disconnect that, and makesure you enable ultra negotiation in the BIOS (if it's availbe, I'm not famaliar with your card). with the scanner and ZIP attached, you can not initiate Ultra SCSI.

Also, what's the sustained transfer you've seen?

 

[HO]

I tried disconnecting the Zip (internal model), but did not see an increase in speed. The scanner is naturally connected externally. Are you saying I have to disconnect it too?

I don't have any software to measure sustained transfer rates.

 

[Zach]

The scanner, if it's on the same card, could have an adverse effect. I don't recall enough to say it will knock down your hard drive's abilities, but it could.

Mine will do things like not allow my zip drive to boot (I run DOS for partition magic).