Re: I/O to ZIP drive temporarily locks up machine
There are those who would have you believe that Damon Muller wrote:
> Hi Chris,
>
> Quoth Krzys Majewski,
> > I don't know how to say this properly.. when backing up files from my
> > IDE hard drive to my parallel port ZIP100 drive, the machine
> > occasionally blocks: it's like everything freezes for about half a
> > minute before I can do anything again. This only happens when the ZIP
> > drive is running (not sure if it's R or W or both). This is with
> > kernel 2.2.17, using the imm driver as a module. I've set all the
> > default "safe" options for the driver, like "slow and reliable" or
> > whatnot. Is this a kernel bug? IMM driver bug? User bug? Feature?
> > Help? chris
>
> After having recently resurected my parallel zip drive and connecting it
> once again to my debian machine (decided that it might be a good idea to
> back up my thesis...), I've also experienced similar problems.
>
> Using the zip drive under both windoze and linux I've seen it eat up so
> much cpu time that the system goes very choppy and is unusable while the
> transfer is going on. I don't know if this is a bug in anything in
> particular, or if writing that much data through the parallel port is
> just a really tough job.
>
> Unless anyone else can offer a more concrete suggestion, I'd recomend
> that when copying large files to your zip, it's probably a good
> opportunity to go and make yourself a coffee!
>
It's possible that Linux is using PIO mode for data transfers over
your parallel port instead of DMA. Check /proc/parport/0/hardware
(assuming you're using the first parallel port). If there's no DMA,
make sure the port is in ECP mode with a DMA assigned to it in your
CMOS settings, and read the parport docs in the kernel source.
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