Benchmark confusion

[waynestewart]

I’m a little confused

I hauled an 8600 with a 450mhz G3 card out of my storage locker. It had a Sonnet SATA card connected to a SD card adapter. This setup was a little faster than the built-in SCSI but not a lot. So I connected the SATA card to a real SSD. With MacBench it showed as being 4 times as fast as the SCSI.

I don’t have many SATA cards and there may be places I’d rather use it so I thought I’d try a spare Sonnet ATA133 card. I connected it to the SSD via an ATA adapter. It benchmarked as 4.5 times as fast as the SCSI.

Then I thought I’d try a Sonnet ATA66 card. It also benchmarked as 4.5 times as fast as the SCSI.

 

[joevt]

What was the Sonnet SATA card?
https://www.sonnettech.com/product/legacyproducts/tempo_serial_ata.html

Using 40 or 80 conductor cables for ATA?
8600 has 50 MHz bus?
Measuring MiB or MB/s?

What SD card?
What SD card adapter?
What SSD?
What ATA adapter?
How fast was the built-in SCSI? < 10 MB/s max
How fast was the first SATA card with SD? ≈ 10 MB/s maybe more or less
How fast was the first SATA card with SSD? < 40 MB/s
How fast was the first ATA66 card with SSD? < 45 MB/s
How fast was the first ATA133 card with SSD? < 45 MB/s

I guess you're confused about
- Why the speeds are so much slower than the max PCI rate of 133 MB/s? PCI real world is more like < 100 MB/s?
- Why ATA is slower than SATA?
- Why ATA133 is not faster than ATA66?

There's some notes in Technical Note TN1008 Understanding PCI Bus Performance
https://developer.apple.com/library/archive/technotes/tn/tn1008.html
It seems to indicate that PCI bus master (DMA) can perform reads (write to RAM) more than twice as fast as writes (read from RAM).

Does which slot matter? Is it the only PCI card in the 8600? Are you using built-in video or a PCI GPU?

 

[joevt]

A more readable version of the Technical Note TN1008 "Understanding PCI Bus Performance" exists in the PCI Driver Development Kit 2.0

 

[Coloruser]

See this thread…. HD speeds.

The theoretical max. is a far cry from what the actual Apple implementation offered in real world throughput. A more modern G3 beige reaches roughly 50mb/sec with a SATA card. The 8600´s fast scsi bus has a theoretical max. of 10mb/sec - x4 or even x4.5 of that is exactly what you would expect from such s machine paired with a SATA or ATA card. Everything faster than ATA66 is not going to show any additional benefits.

 

[waynestewart]

The SATA card came with the SD adapter. I don’t know the brand. More likely it was just a slow SD card. I have a number of extra small SSDs so I likely won't use it again.

What I found confusing was that I got better speed from the ATA cards than the SATA card. All using the same SSD. I also expected better performance from the ATA133 than the ATA66 card. My guess is that with the 50mhz bus and the 32 bit pci slots the speed is limited so ATA66 is as fast as any.

Looking at the Sonnet SATA card specs, it doesn’t list anything earlier than the B&W G3. So maybe it isn’t 100% backward compatible with earlier Macs. Works but not as fast as it could be.

I left the ATA66 card in the 8600 and I’ll save the other two for G3s or G4s .

 

[Coloruser]

I left the ATA66 card in the 8600 and I’ll save the other two for G3s or G4s .

The G3 b/w as well as the beige G3 benefit from the SATA card. The Sawtooth G4‘s ATA66 bus is almost as fast as a SATA PCI card. 60mb/sec in ATA66 vs 75mb/sec with the SATA card using the same SSD. Later G4s ATA100 bus is faster than a PCI based SATA card.

 

[waynestewart]

I had my G4 Digital Audio out and decided to do some benchmarking. It has a processor upgrade, a Sonnet dual 1.8ghz G4.

On the built-in ATA using an adapter with a SSD I was getting 60 MB/S reads

The ATA66 didn’t do quite as good but close enough that I’d never notice

With the same setup on the Sonnet ATA133 card I got 80 MB/S reads

With the Sonnet SATA card I got 102 MB/S reads

 

[Coloruser]

On my MDD 1.25 dual, I am getting around 59mb/sec with an SSD on the ATA66 Bus and 95mb/sec on the ATA100 bus. The same SSD on the SATA Card reaches 96mb/sec. So it seams that the later G4s have a PCI throughput ceiling of around 100mb/sec. That's why I did attach the MDDs SSD just to the ATA100 bus, the SATA card (Adaptec) doesn't bring any benefit. However, on earlier G4s with ATA66 and especially on G3 beige (PIO Mode4) and G3 b/w (ATA33), the SATA card made a big difference.

 

[waynestewart]

I’m getting a slightly less on my MDD but the SSD is an old slower one.

It came off an old RAID array I picked up with a bunch of hardware.

 

[CC_333]

The MDD has faster PCI slots (66 MHz versus 33 MHz on all the other G4s). Does that make a SATA card faster on the MDD, then? If not, why?

c