SCSI harddrives, diff in speed????

[MadMax]

What model #(s) are your hdds? Are they EXACTLY the same? Are they connected in-line(one IMMEDIATELY AFTER the other) on your ribbon? Is your primary faster or your secondary? Have you tried to bench with all other SCSI devices disconnected? Have you tried to bench with only one drive connected at a time? There are about 15 different reasons this could be happening, please provide some more info.

[This message has been edited by MadMax (edited 07-16-99).]

[FastEddie]

Just had the same problem with my pair of 9.1 LVD Viking II's on a 2940U2W controller. I updated the controller bios, which disabled the write-back cache for the drives. Once I enabled the drive cache in the scsi bios, they were back to normal.
FastEddie

[christer]

Hi!

I have 2x 9,1 GB ibm scsi disks, they are set up on a Adaptec 2940UW controller card. The drives are identical, but they really differ in speed. It doesn't matter what benchmark prog I use one of the disks is twice as fast as the other one. How is this possible?? They are on SCSI ID 0 and 1. I have a DVD and a cdburner on 2 and 3, how is this possible???

[christer]

The model is DDRS-39130 and they are EXACTLY the same. I know that this model comes in 2 versions from IBM, one has LVD/SE whatever that is and one don't. There is a jumper to enable SE on the LVD/SE disks and on the same spot on the other disks is TERMITATION ON. My disks have LVD/SE and I have not enabled SE on any of the disks. It is my primary that is slower. They are connected in-line on my ribbon. There are no more connections on my scsi cable. I have not tried to benchmark with only on disk conneted at a time but I will try that.

I installed a new benchmark witch came with the disks. It's the adaptec EZ-SCSI 5.0 and with that tool the disks are exactly the same speed. I can benchmark both at the same time. If only benchmark on at the same time they are still the same. This is verry strange. The other benchmarkprogs i've used is. Sandra, Quadrat check CD98, and another wich i've uninstaled so I can't remeber the name on it :-(

[FastEddie]

First off, you need to enable the SE jumper on both drives, as you are not using a U2W controller. That will switch the drive to the Single Ended protocol, instead of the LVD/U2W. Then I'd also check in the scsi bios to see if you have both of the drives cache enabled.

Just my $.02
FastEddie

[MadMax]

FastEddie is right. Disable lvd. Your disks are trying to use Ultra2 protocol and your adapter doesn't support it. That would cause a timing problem, especially on the primary device on the bus (your primary disk, in this case.) LVD=Low Voltage Differential.....I think that there is some math involved there, somewhere...lol http://www.sysopt.com/forum/wink.gif

[christer]

Thanks guys! I'll try that right now :-)

[christer]

Thanx everybody! It worked, they are now alittle bit faster then they where before, but my primary disk is really alot faster. Do you guys think that if I got my self a U2W controller that I would gain alot of speed???