A4091 SCSI transfer speed

[Morley]

Just a quick question...

How fast is really the A4091 SCSI controller? I'm using the internal one on my A4000T, and I can't get more than directly below 8MB/s at max.. and this is from a 18GB USCSI drive that really should be faster than this.(I expected it to stop at about 10MB/s which is the FSCSI2 maxspeed...)

Is it the Zorro-bus that is the bottle-neck, or? I'm also using a poor old C=3640 as CPU, maybe this is the cause...

Or perhaps I should be very satisfied with these results. Gimme your benchmarks please!

[Effy]

You get 8 Mb/sec I don´t know of any benchmarks of scsi, only ide with a Powerflyer and this on a 68030, but your 8 Mb/sec sure does look good !!!

[Morley]

Well, since it is a DMA controller, I expected it to go very near the 10MB limit of FSCSI2, with a fast disk. But maybe in reality it is not posssible?

[adolescent]

8MB/s is pretty good.  What program(s) are you benchmarking with.  I can run it on mine to see what kind of speeds I get.

[Morley]

I'm running the benchmarks on Sysinfo, using FFS as filesystem(doh). Filesystem shouldn't matter though on raw reads I suppose.

[platon42]

I'm getting about 9MB/sec, if I start SysInfo right after SetPatch (I remember it being a bit higher even with FastRom enabled). Unfortunately, the duration of the benchmarking process is much too short, therefore the results are a bit inaccurate. After booting the speed is still around 8.6-8.8MB/sec. The harddisk is an IDE drive connected through a IDE->SCSI adapter. I do think the onboard SCSI controller performs very well and close to the theoretical limit.

[JuvUK]

hi all,
  i have an A4K 040@25mhz, 2 mb chip, 16mb fast, buster 11 and an A4091, i don't understand how you guys are all pushing between 8/9mb/s when i can only get 4.2mb/s.
  what is wrong with my setup? is there something i'm doing wrong?

cheers, JuvUK

[zipper]

You never get close the theoretical maximum; my best speeds with Blizzard SCSI were about 8.5 MB/s - but older drives did about 6 -7.

[zipper]

is there something i'm doing wrong?
cheers, JuvUK

Using Synchron mode?

[JuvUK]

i'm at work at the mo, but i will check the jumper setting tonight (as i can't remember) but would Synchron really give me an extra 3.5-4mb/s extra transfer speed?

8mb just seems a bit high

[fitzsteve]

Hey Juvvy!
 
My Bliz PPC SCSI & FastATA both give 4.2mb/sec I think its MaxTransfer related as all my CF's and HD's are the same and all were setup the same on Classic Workbench OS3.9
 
Steve.

[JuvUK]

hiya bud,
  i'm using a SCSI hd not a cf, i was quite happy with the 4.4mb/s until i saw this thread, i mean there's a BIG difference between 4.2mb/s and 8-9mb/s, and i just wondered how they are getting these speeds?

[fitzsteve]

hiya bud,
i'm using a SCSI hd not a cf, i was quite happy with the 4.4mb/s until i saw this thread, i mean there's a BIG difference between 4.2mb/s and 8-9mb/s, and i just wondered how they are getting these speeds?

Hey mate,
 
Not only using CF's using SCSI-IDE and 7200rpm PATA HDD at the same speeds...
 
Did buy a SCSI HDD from flea bay but it arrived DOA so not able to test real SCSI drives yet.
 
Anyway if I figure out how to unleash the faster speeds I'll let you know
 
Stevo.

[zipper]

i'm  but would Synchron really give me an extra 3.5-4mb/s extra transfer speed?
8mb just seems a bit high

No exact figures but the difference is noticeable, in my Blizzard more than 2 MB/s.

[JuvUK]

syncron is on