After a few trial, I've been able to drive my ditto max with the Sept 11th
version (unstable) of ftape.
Now, I observe that the speed is very slow. I got, on the average, about
2Mbytes/minute: this means that, for a backup that is expected to fill a 5MB
tape, it will be necessary more than 41 hours!!! This fact seems strange.
So, I had a look at the system log, and I saw that very often there is an
"overrun error" followed by a retry that writes ok. Each overrun is
accompanied by a audible tape rewind of about a few 100ms. It's obvious that
such a lot of mechanical rewinds increases the total time needed for a
backup, so slowing down the entire process.
I made a trial on the same pc, booted with dos, running the "ditto tools"
program furnished by Iomega. Doing a backup with this, there is no audible
rewinds, and the backup completes at a speed that is not revolutionary, but
is almost three times faster than the linux trial.
So, it's clear to me that the problem is not hardware. The documentation
states that in order to avoid overruns, the parameter ft_fdc_threshold
should be put at 15. But this doesn't bring to any improvement.
Is there a way to avoid the overruns?
P.S. the configuration of the EZ board is quite correct. The same io/irq/dma
found by isapnp has been used for the ftape initialization; they are not
used by another application; the ft_fdc_threshold is 15.
Thank you in advance.
Fabio Lissandrini
