SCSI controller comparison

[mr_silicon]

Just out of interest, I was wondering if anyone has ever compiled a list of the performance (i.e. transfer speed) of common SCSI controllers? For example what can we expect out of A2091, A3000, A4000T, FastLane, CyberStormPPC etc.?

Clearly performance is affected by the drive, CPU and other factors but I would be interested to see a comparison of theoretical maximum speeds and those achieved in practice.

[darksun9210]

cyberstormPPC/060
ultrawide scsi seagate 18Gb with a 2/4KB block size, i got around 22MB/s. i dare say even faster with more modern drives.

A4000T/warpengine040scsi/Cyberstorm2-040scsi
scsi quantum fireball 9.1Gb with 2KB block size, i got just over 7Mb/s in async, and nearly 10MB/s in Sync mode.
i guess this counts for the A4091 and fastlane aswell as they use the same chip, but i've never owned an A4091 or fastlane so can't confirm.

A3000 i've never owned,

A2091 in an A4000, its best to have some ram onboard for the scsi chip to DMA into, there is a patch on aminet for this, but then you are limited to the Zorro2 interface at around 2+MB/s
without the onboard ram and the patch, an A2091 in an A4000 gets about 150-200KB/s in my expirience.
A2091 in an A2000, can dump into zorro2 ram anywhere, but again the zorro2 interface is the limit.
The GVP HD8+ is again limited by the zorro2 interface, but doesn't have the DMA issues the A2091 has in an A4000.

The blizzardIV030/040/060 scsi can happily manage 10MB/s as can the blizzardPPC scsi, as these are direct DMA devices on the processor bus.

basic rule of thumb. the more modern the drive, the better.

i hope this helps.  :-)

[A4000_Mad]

@ darksun9210

That's one hell of a good reply :pint:

[darksun9210]

cheers matey  :-)

oooh, i forgot, there is a FAAAAAAST rom upgrade available for GVP scsi controllers covering GVP's HD8+ series for A500/zorro2

basicly from what i can understand, it enables longword DMA transfers over the Zorro2 bus. you need some fast ram in the zorro2 address range, but it can squeeze out nearly 3.6MB/s!  :-o
i dunno, sounds like witchcraft to me :-D

[Retro_71]

What about the A3000 does anyone know how fast that can be and also what does the 08 rev chip do for it?
And where can i get the updated chip from?

[darksun9210]

no idea how fast, but you can get it from here:-

software hut W.D. scsi chip rev8

hope this helps :-)

[adolescent]

My A3000 got between 2-2.5MB/s.  I've heard it's capable of more but I've never seen it.  The updated WD chip fixes some problems, it doesn't make it any faster.

[countzero]

A3000 scsi interface is the same as A590/A2091 I guess.

[adolescent]

It can go faster (I've heard ~4MB/s) with fast drive and faster processor.  Fastest I had at the time was a Quantum Fireball 1GB and a couple of AV Micropolis drives.  (Drives that are only rated at 5-10MB/s)

[Zac67]

I've got an aged Toshiba 1 GB drive in my A3k - close to 3 MB/s. The driver can only do async transfer, so ~4.5 is (very) theoretical max.

I've seen A590/A2091 do ~1.2 MB/s (with 50-200 MB drives 15 years ago), which isn't bad for a 68000 machine, but a faster CPU will make that much slower (due to bus sync overhead and/or driver issues).