HI Hendrik,
How are you measuring the speed? Are the tests all done at the
same time? What is the contents of /proc/bus/usb/devices with one of the
"slow" ones plugged in? One issue in the 2.6 kernel is that you could be
using the Low Performance USB SCSI driver (ub). That doesn't explain the
Firewire problem though...
regards,
Stephen.
On Sun, 24 Apr 2005, Hendrik Muhs wrote:
> Hello,
>
> I have a strange problem with kernel 2.6.11.7 a Via KM400 based motherboard
> and external harddisks.
>
> I get only up to 500kb/s write speed over USB 2.0 and also FireWire 800. I
> have tried several combinations of harddisks, external cases (with different
> chipsets)
>
> The following table summarizes everything:
>
> connection chipset harddisk case harddisk speed
> USB-2.0 oxford 922 LaCie Big Disk ca. 500 kb/s
> USB-2.0 pl-3507 250 GB Seagate ca. 500 kb/s
> USB-2.0 oxford 922 250 GB Seagate ca. 500 kb/s
> USB-2.0 pl-3507 40GB IBM ca. 3-4 MB/s
> FW-800 oxford 922 LaCie Big Disk ca. 500 kb/s
> FW-800 oxford 922 250 GB Seagate ca. 500 kb/s
> FW-400 pl-3507 250 GB Seagate ca. 500 kb/s
> FW-400 pl-3507 40GB IBM ca. 18 MB/s
>
> All harddisks are ok and function normal on other systems.
>
> I have also tried a 2.4 kernel (a Knoppix Live CD with 2.4.29) which gives
> good results with the oxford 922 and the 250GB hd. Unfortunately I have to
> use an 2.6 kernel, because I need special drivers.
>
> The FW-800 card is based on a Texas instruments chipset and functions ok on
> the other system.
>
> It is strange that the problem seems to be not FW or USB related, maybe the
> SCSI subsystem?
>
> Also strange: I get better results with a smallsize (40GB) harddisk than with
> a big size (250GB) harddisk with the same case/chipset combination. The
> troughput is still too small (3-4 MB/s) but at least better.
>
> Has anyone an idea what is going wrong here?
>
> Or maybe can guide me, how to debug this problem.
>
> Hendrik
>
>
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