--- Alec Shaner <[EMAIL PROTECTED]> wrote:
> Richard Fish wrote:
> > Alec Shaner wrote:
> >
> >
> >>I recently purchased a WD 160GB external USB drive
> and can't get it to
> >>perform reliably on my server. It works fine when
> connected to my
> >>workstation machine (a P4P800 ASUS MB with USB 2.0
> support). The server
> >>only has 1.1 USB support, but the problem is that
> it starts out copying
> >>fine at about 11MB/sec and then after a bit slows
> to a crawl and stays
> >>that way. I have formatted it with an ext3
> filesystem. Here's all the
> >>info if anyone has an idea.
> >>
> >>
> >>
> >
> >
> > With USB 1.1 you are not going to get more than
> about 1.2MB/s
> > throughput, because the top speed is 11
> megabits/sec, not megabytes:
> >
> > 11 mbit / 8 bits-per-pyte = 1.375.
> >
> > The initial burst you see at 11MB/sec is likely
> due to buffering.
> >
> > -Richard
> >
>
> Once the buffer fills up would you expect it to work
> fine at 1.2MB/s? I
> wish I had kept the logs, but it was extremely slow
> (much slower than
> 1.2). I was copying a series of ~70MB files over and
> it would work fine
> on about the first 5 or so files before croaking. I
> eventually had to
> kill the job.
Hi Alec,
I suspect Richard is right on. If you run "free"
before your start the copy and then again after the
burst you should see that it simply ate up the
available memory. You should do a real benchmark,
possibly including hdparm.
If there is really a problem then hopefully you will
see some errors in dmesg or the syslog
(/var/log/messages). You may need to enable debugging
for the filesystem and/or usb-storage driver.
Zac
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