AT&T 3b2 vs SCSI2SD drive replacement

[Swift Griggs]

On Wed, 1 Jun 2016, Josh Dersch wrote:
> The advantages of the SCSI2SD over the ACard are as follows:

Heh, I just ordered one. I'll test it vis-a-vis the ACARD device and post 
my results here and on Nekochan where I originally posted about the ACARD 
adapter.

> 1) It's open-source (hardware and firmware and software)

Ohhh, nice. I didn't realize that. Very cool. 

> 2) The developer is extremely responsive to bug reports / feature 
> requests

That's always a plus, but I doubt I'm going to try it on anything too 
spacey. I'll just be my SGIs and the one Amiga 3k.

> 3) It's very flexible -- you can make it look like any drive 
> you want to (important for machines that expect to see only certain 
> drives), it supports oddball sector sizes (for your lisp machines and 
> AS/400s),

I'd probably burst into flame if I touched a LISP machine at this point. 
Though, then again, I'm quite certain there are no Gods in the LISP 
pantheon. Otherwise I'd be riding a thunderbolt by now, and my college 
profs would be with 72 gazelle-eyed virgins. :-P 

NOTE TO LIST MEMBERS: THAT was a JOKE!! (remember those?)

> it can support multiple drives on a single board, pretend to be a 
> CD-ROM, etc, etc, etc. 4) It's considerably cheaper.

That's an excellent feature that I'm sure would come in handy, especially 
if it can emulate a CDROM with a 2048 block size. That'd be super-helpful 
on an SGI, and would probably make the mind-numbing 'inst' operations take 
a little less time. 

> It's probably slower than a real drive some instances, but in equally as 
> many instances that you're going to use something like this, the host 
> machine isn't going to reach peak throughput anyway.

We will see. Lots of folks had the same doubt when I was testing the ACARD 
device. They felt that the SATA disk would overwhelm the SCSI2 bus, and 
they were right. However, what they were wrong about was that the internal 
disk didn't much matter. When I replaced the Samsung 850 Pro with a 5400 
RPM laptop hard disk (still far newer/faster than the SCSI disk) the 
performance dropped considerably. So, while disk throughput was 
comparable, latency was still much lower with the SSD and that had the 
most anecdotal "feel" impact, too.

-Swift