Expected performance w/ USB2 PCMCIA card?

[mvip]

Hi,
I recenlty purchased a VIA 82XXXX-based USB2-pcmcia card, howver I'm experiencing really poor performance. Initially hdparm's test showed about 1-2 MB/Sec to my USB2-hard drive, but after some kernel changes, I managed to get it up to 4-5 MB/Sec, which still is slow.

So, my question to you guys is; what kind of performance can one expect with these cards? Is it reasonable to expect a more than 20Mb/Sec from these cards?

I looked at the CPU usage while running hdparm, and it doesn't seem to spike or anything, so i don't think the computer is too slow (P3 700, 256 RAM).

[chrismortimore]

Assuming you're using Cardbus (a newer type of PCMCIA), you can theoretically transfer 132MB/s, so the interface shouldn't be a problem, it's quicker than USB2.0. My USB2.0 drive (not going through PCMCIA admittedly) runs at about 20MB/s read and write. My Cardbus 10/100 ethernet card can transfer stuff at ~10MB/s, which is what is expected of 100Mb ethernet.

What kind of drive do you have? Also, do you have 32bit support for your PCMCIA socket? lspci will help you with this one. Also check that you have EHCI and UHCI support to get your USB ports running full speed.

Do you have another machine to test the drive with? Sounds a little like the drive isn't using DMA, that should be set by the drive enclosure's circuitary.
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