[l008com]

I've got pages of benchmarks here that I ran all night. I used a 1 GB RAM disk and 1 GB of random video to avoid caches/compression etc. That machine was doing nothing else so this was a pretty good benchmark. I know it was fairly accurate because I got nearly identical numbers every round.

So here is the "problem". I have an MDD G4 tower that has three ATA busses, one for the optical drives, then one ATA66 for two hard drive bays and an ATA100 for two other hard drive bays. Both can see drives bigger than 128 GB. Once I started doing benchmarks, I was very surprised to see that these drives I bought, 3 identical 160 GB models, could read and write at 75MB/sec on the built in bus. I didn't realize hard drives were this fast, especially cheap ones like these.

The ATA66 Bus was topping out at 57MB/sec read and 59MB/sec write. Not sure why the read was a little slower than the write, but still those numbers are very close. But still I plan on making a two drive mirror using SoftRAID. I want the volume to be as fast as possible, so I want both drives running at 75MB/sec.

So naturally I grabbed a Sonnet TEMPO ATA133 card. Put it in there as the ONLY PCI card, and much to my surprise, the drives were running at only 45MB/sec read and 56MB/sec write running off the card. Each HD was a Master on it's own IDE bus, and I test the drives one at a time.
Although I did test the ATA66 & ATA100 at the same time and there was no change in speed. I tested both ATA133's at the same time and the speed dropped a little but it didn't split in half.

So what is going on here? Does the MDD have an exceptionally slow PCI bus, slower than even it's own built in ATA Bus? Or is my Sonnet card just whacked out? With all drives running at their max 75MB/sec, i'd get 75MB/sec writes and 150MB/sec reads off my SoftRAID Mirror. Thats what I'm aiming for. Any thoughts?

[l008com]

John,

Not a clue in the world why you are getting that kind of performance. Maybe the fact that you are going through the PCI bus? As opposed to the direct connection on the motherboard?

You mentioned all the drives were Masters. Of course, you can only use two Master drives on the card since there are only two cables. But I'm sure you knew that. Were you just testing one drive at a time?

Sonnet Customer Service

. . . remind me not to buy any more Sonnet cards . . .

[angelmb]

I keep my HDs as cable select (2003 MDD), would do that make any difference?

[l008com]

I don't see how? CS would just make them choose master automatically.

[Bwa]

According to this page, the MDDs had four 33 MHz PCI slots. Perhaps the internal ATA connectors are on a 66 MHz bus (my MDD is in storage, but you might be able to determine the bus arrangements in the System Profiler--putting cards/drives onto separate busses might help as well).

Good luck.

[l008com]

Originally Posted by Bwa 

According to this page, the MDDs had four 33 MHz PCI slots. Perhaps the internal ATA connectors are on a 66 MHz bus (my MDD is in storage, but you might be able to determine the bus arrangements in the System Profiler--putting cards/drives onto separate busses might help as well).

Good luck.

BUT surely, a 33MHz PCI slot can handle more than 50MB/sec ??

[P]

Originally Posted by l008com 

BUT surely, a 33MHz PCI slot can handle more than 50MB/sec ??

The original (and slowest) PCI was 32 bits at 33.333333 MHz, or 133.333333 million bytes per second. That's some 127 MB/s, so yes - your problem is something else. Don't know what, though.