Stefan Kayser wrote:
>
> Hallo,
>
> I have installed ftape 4.03pre2 on my 80486DX2/66 VLB. Could you
> please tell me whether the writing speed is low or high?
>
> The ft_fdc_rate_limit in my module insert script is 2000.
> If I am doing a
>
> tar -cvzf /dev/nqft0 /med --block-compress
>
> the tape drive streams 253 MB uncompressed data in about 90 minutes.
> If my calculation is correct this is about 380 kbps. The rate based
> on compressed data is at about 250 kbps ( 167MB/90min ). I had about
> 50 write errors.
>
> Verifying the backup with
>
> tar -dvzf /dev/nqft0 --block-compress
>
> takes about half the time (765 kbps uncompressed/ 500 kbps compressed).
> My tape drive is a Iomega Ditto Max connected to the Ditto Dash DX
> Accelerator card. Kernel : 2.0.33. OK, it�s stated in the manual
> that you can�t reach 4 Mbps as it�s specified by Iomega, but
> 250 kbps sounds a bit low, doesn�t it?
>
> What is your experience with the Ditto Max?
>
> Stefan
My experience with ditto max sounds like a tragedy.
As you stated, the speed rate that you'll able to get with ftape is ridicolous. The
reasons of this slowness is related to continous small rewinds of the tape in front of
several overrun errors (as you can see in the logs, and you can ear during the backup).
I tried to ask for a solution to this mailing list, but I didn't get something useful
except for the advice to buy another type of streamer device.
The overrun problem seems to be related to the impossibility of driving the interface,
in a multi-user OS like linux, without accepting compromises that go out (according to
the authors) of the correct rules of programming. Under Windows (that is not, however,
a multi-user OS) these compromises had been accepted: the speed is quite acceptable.
So, I followed thew advice to junk the ditto max and I bought a OnStream DI-30 IDE
tape streamer (15/30GB), that works very fine and is very fast.
Regards
Fabio Lissandrini
