Very slow transfer speeds with external hard drives through Firewire and US

Question

Hi All,
My external drives transfer very slowly on my MacPro. I've been searching for answers and have turned up very little. Apple support suggested I post my issue here. Just to make a note, I measured my disk speeds with both AJA System Test and copying files between drives and reading the Disk Activity in Activity Monitor.
I have 3 external drives, all MyBook Premium or Professional, 1x 500GB, 1x 1TB and 2x 1TB in RAID 0. I had them on Firewire 400 and the RAID 0 2TB one on Firewire 800. My transfers on FW were all around 24MB/sec on all drives (much less than what I should be getting with FW400). I then read somewhere that the FW bus on the MacPro uses the slowest speed connected for all FW connections. So I unplugged everything but the FW800 Raid 0 drive and my transfer rate jumped to 40-60MB/sec. This is much better, but still about half or so of what I expect it should be producing from an external RAID 0 setup.
To keep my FW800 backup drive faster, I've plugged the other two into USB2.0. The transfer speeds on both drives are now hideous, around 10-15MB/sec. This is so slow, but I'm not sure what to try to fix my speeds.
The HD's in the external drives are all 7200rpm, and all should be transferring at a higher rate. Do you have any suggestions or ideas? Ideally I'd like to get everything transferring at rates they should be transferring at, but I'll settle with my current FW800 speed of 40-60MB/sec if I can get my other two drives transferring at a non-snail pace.
Is this a common issue? I can't believe I'm the only one plugging multiple external hard drives into their Mac Pro. I hope someone has a fix or solution for this. I'm all ears!
Thanks in advance.

Answer 1

Hi Kappy, thanks for the information.
So I rejigged my setup a tad. My RAID 0 is still FW800, the second drive is back on FW400 on the back port, and the third is USB 2.0 on the back as well.
It's interesting to note that I saw the FW800 taking a bandwidth hit if the FW400 drives was being read/written to. For example, if I was averaging 50-60MB/sec on the FW800 drives and copy something large to the FW400 drive, each drive averages out to about 30/MB second, roughly half the FW800 speed I was getting. The USB while the slowest didn't cause any slowness on the FW drives.
Here are my Xbench results. These results are from each drive being benchmarked individually with no other drives being tested at the same time.
*MyBook 2TB in a RAID 0 configuration: Firewire 800*
Results 75.42
System Info
Xbench Version 1.3
System Version 10.5.5 (9F33)
Physical RAM 16384 MB
Model MacPro3,1
Drive Type WD My Book
Disk Test 75.42
Sequential 80.92
Uncached Write 69.16 42.46 MB/sec [4K blocks]
Uncached Write 110.79 62.68 MB/sec [256K blocks]
Uncached Read 53.66 15.70 MB/sec [4K blocks]
Uncached Read 136.76 68.73 MB/sec [256K blocks]
Random 70.62
Uncached Write 36.38 3.85 MB/sec [4K blocks]
Uncached Write 140.55 45.00 MB/sec [256K blocks]
Uncached Read 93.26 0.66 MB/sec [4K blocks]
Uncached Read 88.38 16.40 MB/sec [256K blocks]
*MyBook 1TB on Firewire 400*
Results 47.73
System Info
Xbench Version 1.3
System Version 10.5.5 (9F33)
Physical RAM 16384 MB
Model MacPro3,1
Drive Type WD My Book
Disk Test 47.73
Sequential 52.47
Uncached Write 48.45 29.74 MB/sec [4K blocks]
Uncached Write 53.76 30.42 MB/sec [256K blocks]
Uncached Read 43.69 12.79 MB/sec [4K blocks]
Uncached Read 70.91 35.64 MB/sec [256K blocks]
Random 43.78
Uncached Write 17.29 1.83 MB/sec [4K blocks]
Uncached Write 98.83 31.64 MB/sec [256K blocks]
Uncached Read 76.33 0.54 MB/sec [4K blocks]
Uncached Read 97.01 18.00 MB/sec [256K blocks]
*MyBook 500GB on USB 2.0*
Results 40.60
System Info
Xbench Version 1.3
System Version 10.5.5 (9F33)
Physical RAM 16384 MB
Model MacPro3,1
Drive Type WD 5000AA External
Disk Test 40.60
Sequential 35.99
Uncached Write 37.31 22.91 MB/sec [4K blocks]
Uncached Write 37.22 21.06 MB/sec [256K blocks]
Uncached Read 26.62 7.79 MB/sec [4K blocks]
Uncached Read 50.27 25.27 MB/sec [256K blocks]
Random 46.55
Uncached Write 20.37 2.16 MB/sec [4K blocks]
Uncached Write 68.44 21.91 MB/sec [256K blocks]
Uncached Read 93.55 0.66 MB/sec [4K blocks]
Uncached Read 86.71 16.09 MB/sec [256K blocks]
So Kappy are you saying that those speeds look normal?
Thanks