Slooow backups with BRU

[Mike Gigante]

I don't know about 1/2" tapes, but on our exabyte, we sped bru up
*considerably* by increasing the buffer size to ~ 1Mb. Unfortunately
I have found the double-buffering option to bru to be unreliable as
this would be even faster.

e.g. bru -cv -b 1Mb -f /dev/xtape ...

the larger buffer reduces all the back and forth tape motion that
is needed to get to streaming speed (for a little 20k write).

buffers larger than 1Mb didn't seem to win much. (This was a very
qualitative trial!!)

Mike Gigante,
RMIT Australia