Linux on PE2950, PV220S and very slow PV124T

John LLOYD jal at mdacorporation.com
Tue Aug 26 11:00:15 CDT 2008


> >   
> Hi John,
> 
> TAR_OPTIONS is empty.
> 
> % date && echo "" && tar -tb 128 -f /dev/st0 > /dev/null && 
> echo "" && date
> 58 mins !

Hmmm, this might be good news -- an LTO3 should take about 3 hours to
fill up when writing or read out when full.  So if this tape was 1/3
full, then this was successful.


> 
> % dd if=/dev/zero of=/dev/nst0 bs=1M
> dd: writing `/dev/nst0': Device or resource busy
> 1+0 records in
> 0+0 records out
> 0 bytes (0 B) copied, 2.43528 seconds, 0.0 kB/s

Ahh, might you have backup software running or something else going on?
This shouldn't happen unless there is competition for access to the tape
drive.  I've also seen this when drives were rewinding or doing
something else like loading a tape, so try again.....also you didn't
show the count= part.  You need to write at least 1 GB to a tape to get
a reasonable timing.  1GB is 1M block size times 1000 (count=1000).

> 
> For tar, i should use tar -b 128 -cvf /dev/st0 et not tar -cvbf 128 
> /dev/st0 or tcsh make an error... :)
> 

Oops, my fault.  Omit the dash; GNU tar has completely different
behaviour between "-tvbf", meaning a blocking factor of "f" which is of
course invalid, and "tvbf" meaning two parameters, for b and f, follow.
Your version works too.


--John



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