Stefan Kayser schrieb:
> 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.
> ...
To use a floppy controller based streamer at reasonable speeds
you need at least a machine of the Pentium class (P75 should be
enough for 2000kbps, my experience with ditto 2GB and ditto dash
accelerator board).
So, as along as you are using your 486 based machine your won't
get more speed. The problem is, that your CPU isn't able to put
enough data to the tape drive to keep it streaming, so the drive
has to stop, wind back and start again. This behaviour, also
called shoeshining, reduces your total throughput significantly.
It may be possible, that your CPU would be able to feed 1000kbps
continiously but ditto drive max needs at least 2000kbps. This
leads to the situation that overall system bevahiour is dominated
by your drive winding back and forth.
Solutions:
1. Use a new m/b
2. Switch to another, less CPU consuming backup technology (IDE
based travan, SCSI based travan, DAT or QIC drives).
> ...
Martin
--
Martin Jacobs * Windsbach * [EMAIL PROTECTED] und
[EMAIL PROTECTED]
Registered Linux User #87175
