Backup on DDS-4 tapes

[Alex Zbyslaw]

Ludo Koren wrote:

># /sbin/dump -Lu0 -B 41943040 -C 32 -f /dev/sa0 /usr
>
>  
>
I would guess that your tape drive does hardware compression in which 
case the amount of data which fits on a tape is variable.  In such a 
case you can't tell dump how big the tape is -- I haven't used options 
like -B since 1600bpi reel-to-reel tapes, except in my day you specified 
how many feet of tape you had :-)

from man dump

     -a      ``auto-size''.  Bypass all tape length considerations, and
             enforce writing until an end-of-media indication is returned.
             This fits best for most modern tape drives.  Use of this option
             is particularly recommended when appending to an existing tape,
             or using a tape drive with hardware compression (where you can
             never be sure about the compression ratio).

Don't know -L, must be a 5.x thing.  Try:

/sbin/dump -Lu0 -a -C 32 -f /dev/sa0 /usr

I use -b 64 as well.

Use cpio/tar at your peril as they may not do devices right and may not understand filesystem flags.

--Alex