[rescue] Block size and the single DD
Sheldon T. Hall
shel at cmhcsys.com
Wed Feb 11 11:32:24 CST 2004
Mike Meredith says ...
> > Sheldon T. Hall wrote:
> > > rsh $MACHINE xfsdump -l 0 -F - $FS | dd of=$TAPE bs=$BS
> > >
> > > I run that on the Sun with values like
> > >
> > > MACHINE=blinky # Indigo2 R4k
> > > FS=/dev/root
> > > TAPE=/dev/rmt/1cn # DLT 2000xt on Sun SBUS card
> > > BS=1024k
> You might want to reduce the block size to 32Kbytes. The backup script I
> used to use at work used that block size to write to an L280, and I'm
> pretty sure I benchmarked a wide range of block sizes to check the time.
I'm going to look into the optimal BS for the DLT ...
> I seem to recall some people have trouble with blocking over rsh, so it
> may be worth trying something like :-
> rsh $MACHINE 'xfsdump -l 0 -F - $FS | dd bs=$BS' | dd \
> of=$TAPE bs=$BS
... and maybe use ibs= and obs= with dd, to match the "ends" of the pipe.
> Don't forget to sprinkle the chicken blood around.
Fortunately, my wife's a chef, so I can get that stuff by the bucketful.
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