Parity Checking on A3000 scsi bus

[22dave66]

Is it a good idea to set all scsi devices jumper settings to Parity Checking - ON

I'm reinstalling my scsi devices on the internal A3000 scsi connector with new cables and active terminators, also adding a replacement hard drive. The devices are hd - hd - cd - tape, currently only the 2nd hd has Parity set ON.

I had a faulty ribbon cable (years ago) and data between the hd's and tape was written with errors but not reported, would Parity Checking have picked this up?

[Kin Hell]

Parity Enabled will just add that little bit more to SCSI Checks across the whole Bus. Any errors found will get the data re-transmitted.

Not all SCSI devices will always run with Parity enabled. Other Devices on the Bus could be the cause; - It's a bit of a Dark Art in some ways....

I'd always set Parity Checking to ON if my Tape Streamer or Optical Device allowed it. Personally & RE: Hard drives, I wouldn't be so bothered about them.

[22dave66]

Cheers, Yeah it looks like it is a bit of dark art, the Compaq drive iv'e just added won't even spin up with parity jumper set on. I will look at it again after i figure out why the active terminators iv'e fitted are locking up the Scsi bus!

[Kin Hell]

Ooooh! - Compaq SCSI Drive.... Going back to Old School SCSI....

Companies like this had their own way of fudging things with their own brand products back in those days.

As a matter of interest, how young is your model & what type?

Also, be sure to run Termination on the Mobo & after the last physical device. - Be very interesting to see if that works for you.

Also, what Tape Type?

[22dave66]

HP/Compaq C2490A 2.1 gb half height, no manufacture date but all the chips are dated 1993/94! My old (dead) drive was made in 1995 so it's in that vintage.....

2nd hand scsi prices on Ebay etc are crazy so i looked locally and found a tech recycle company called (plug) Ultratec.co.uk, i got two of the Compaq drives for £23.98! (one for a future replacement)

Mobo termination and on board termination of the last device (tape: Archive Viper 2150s) isn't stable enough, the cable is about 1.5mtr. Active terminators were locking the scsi bus but i think iv'e found why - D800/term power diode on the A3000 is cracked in half!

[Kin Hell]

WOW!! - Almost look Prehistoric don't they!



I have several Samsung 4.3GB SCSI drives here if you're interested. - Same profile as the Quantum LPS series, 1".

That aside, When I had my A3000D, she had 2 x Quantum SCSI drives in the box with Termination on the Mobo. Out of the back of the A3K's External SCSI, I ran a 25 way cable to a Centronics 50 Way header that connected to the 50 Centronics on the back of my External SCSI Box. - The next device was a Seagate 5.25" half height SCSI drive with terminators installed to the drive. My Archive Viper 150 would only work without being Terminated & being after the last terminated device. - Now you might appreciate my earlier comment about your results being interesting after I suggested you did it by the numbers & include the Viper inside Termination. My set up just would not work by the numbers; - Dark Art indeed!