Shouldn't this SCSI drive be faster?

[Syntho]

I have a Sonnet SATA card in a 9600 along with an SSD from OWC. In a real world test, I got about 10MB/sec transfer rate going from one directory on the SSD into another. That doesn't seem like it's going as fast as it should so I decided to test the hard drive and came up with this result:

That looks much better, but still, I thought a real world test would be faster than 10MB/sec. More importantly, that SCSI HD seems way slow for what it is. That's a 15k RPM Cheetah drive so I thought I'd have a bit better speed than that. I was thinking close to 10MB/sec or something as the SCSI bus would allows for. Is something wrong with my HD?

 

[Trash80toHP_Mini]

It's almost invariably something to do with Apple's implementation of the SCSI Standard when performance issues arise. Have you got a PCI SCSI Card to benchmark against the MoBo for determining the 9600's level of sub-Standardization?

What's the SCSI interface level of your Cheetah? Is it baseline Fast, Fast/Wide II or adapted Ultra?

 

[uniserver]

you are only going to get so much data through that PCI bus.

its like a Nubus 10/100 nic card,   --- well its kind cool that you can link at 100mb's lol  that is about it, you not going to get much gain.

 

[Syntho]

The SATA SSD in there (benchmark to the left) got 25MB read/write average, so I guess that can serve as an equivalent of using a PCI SCSI card.

I believe the Cheetah 15k.4 is an Ultra320 drive, and its specs say it should be able to get 96MB/sec as noted here: http://www.seagate.com/files/docs/pdf/en-GB/marketing/Seagate-Cheetah-15K-4-gb.pdf

I'm using an adapter to get the Cheetah to work in the 9600. It's like a U320 to normal SCSI2 or something, just whatever is in the Powermac 9600 by default. The speed it's giving me would make more sense if I had this hooked up to the external SCSI bus, but it's definitely on the internal one since the ribbon cable is going from the motherboard to the adapter on the drive. I was hoping to hit like 8MB/sec or so on it.

If these are 'normal' speeds for a 9600 in this setup then no worries. I'm just not sure that this is actually normal or not.

 

[Unknown_K]

Built in SCSI on the 9600 is very dated and slow.

 

[johnklos]

You'll never get 96 MB/sec except to/from the cache on a 36 gig drive. Size does matter - the larger a drive, the higher the density and the more data passes under the heads per rotation. The only time 15k RPM really matters is with rotational latency, since with little I/Os you wait less for the data you want to come under the heads because of the faster rotation. A 2 TB 2.5" 5400 RPM drive would be many, many times (easily an order of magnitude) faster than a 36 gig 15k RPM drive, for instance.

The busses on a PowerMac aren't very fast on their own, so it's not surprising you're not getting good performance. Also, there are two motherboard SCSI connectors inside the case, so even if the drive is internal, the cable could still be plugged in to the bus that's part of the external bus. Double check. The screenshot you posted shows it as bus 0, but I don't remember if internal is 0 and external is 1 or vice-versa.

 

[Trash80toHP_Mini]

Also check for complete and unadulterated ultra bus termination. ISTR something about error checking/re-reading processes eating up throughput, but I'm sleepy, YMMV.

 

[Syntho]

Everything is connected fine, the SCSI HD is going to the internal SCSI 0 bus and the 2nd SCSI bus (1) has nothing plugged into it. I'm thinking that if I had multiple SCSI drives in the SSI chain I'd probably be able to get closer to 10MB/sec, but I'd have to do that simultaneously. It probably just doesn't go faster than 5MB/sec per SCSI device for whatever reason.

While I'm at it, I'm curious about the internal connector for the external SCSI bus. I looked for some documentation but I didn't find anything on how the internal connector and the external connector play together for bus 1. Did they put an internal connector in there for bus 1 so people could load more HDs into it instead of worrying about external gear? Maybe plugging something into there makes the external connector not work.

 

[Trash80toHP_Mini]

Checked the DevNotes. Your 9600 uses the same MESH fast SCSI controller as the 9500, a Fast/Narrow (50 pin/8bit) SCSI II bus. That's just one horrible choke collar/leash to put on your Cheetah. You should look into a PCI Ultra Card to see any significant throughput improvements, no need for an adapter, just the internal cable.

You've got a SATA card in there for heaven's sake, go Ultra! ;D

 

[NJRoadfan]

Onboard is limited to 10MB/sec on the "Fast" internal bus. It was speedy in 1995, not so much nowadays.

 

[HoneyDoe]

No there should be two scsi ports on the main baord,

one for slow legacy scsi and one for fast scsi,

If your system has it, try it. if not that sucks.

 

[Syntho]

I never expected the SCSI bus to be very fast, I was just thinking that since it was rated at 10MB/sec that I'd get something closer to 8MB/sec on my SCSI HD. That's why I suggested that maybe the bus as a whole is CAPABLE of 10MB/sec, but it won't let me get anywhere near there unless I have two drives on the same bus and write to them at the same time. So maybe 4-5MB/sec per drive is the norm. I wouldn't know since my 9600 is the only older Mac that I have.

 

[Unknown_K]

Some drives don't like being downgraded to 50 pin bus from 68.