Blizzard PPC scsi transfer speeds

[alewis]

@Boot_WB

Interesting hack on the cable, personally I prefer to use 50-68 adapters. Can you confirm the drive is an LC model, as LC is seagate's terminology for an 80pin SCA interfaced drive.

I'm sure the problem is OS related, but from own experience:

Having a good few of these drives meself (and the W variant) a few years ago, I was getting less-than-satisfactory results. I changed the PD jumper (which had been set to do parity checking). YMMY.

Also, try changing the SE mode jumper. LVD drives should fall back to SE operation without the jumper set, and this *may* lead to performance boosts. OTOH, you of course may have it set because they didn't! Just gotta love the black art of SCSI.

If you have a couple of adaptors, it might be worth using a native 50way cable, and 50/68 adaptors to attach the drives. IIRC you should have a narrow (native 50pin) SCSI device as the last device in the chain, and use an active terminator at the end of the chain (sorry, can't see original post to remind myself of setup).

sorry about the egg suck, but I always find it useful to check from the wire up, even when I *know* it isn't an issue...

Um, reaching back into the dim distant past when I last used a Miggy in anger... the disk buffers are in fastmem, aren't they?

[alewis]

£2 a pop! I remember the first UW drives I got - 9.1gb Barracudas at £700 a pop. I *knew* I should have sold them on then!  Still use them in a Netware box, and tend to use U160 versions as server boot drives.

Anyway> Maplins are reasonable for Molex connectors, although a local PC shop would be cheaper. The SCA adapter is always a suspicion. Going off topic slightly, the "cheap" ones found on ebay are crap. Literally. I buy mine from SCSI-4-ME in the US

SCSI-4-ME SCA-68 pin adaptor info

They are very, very, very good. Ok, only of use in a u160/320 chain, but I even had problems in an older UW chain using cheap adapters. The first two are common as crap on ebay, and over in 2cpu storage forum are the major source of "scsi newbie" issues.

But yeah, it does seem to be an OS/memory issue. 8mb on the bus is about right for SCSI-2 (though, that 2mb overhead is a little high, imho. Maybe the chipset logic).

I take interest in this as I have an A4K, and one day will get round to making it work again; it was fine with the WarpEngine (and the onboard SCSI seemed fine), then I bought a Cybestorm PPC - about 18months ago! - and have yet to fit it. I really, really, really want to see how ultra-wide SCSI on the Mig performs!