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This is a program designed to speed up writing tapes on remote tape drives.
Requirements are shared memory and locks which normally means that these are
supported in your kernel. [for FreeBSD/NetBSD, this means you MUST have a kernel
with options SYSVSHM compiled in - markm]
Buffer has been tested under SunOS 4.0.*, SunOS 4.1.*, Solarix, HP-UX 7.0, and
Gould UTX 2.1A (sv universe).
The program splits itself into two processes. The first process reads (and
reblocks) from stdin into a shared memory buffer. The second writes from the
shared memory buffer to stdout. Doing it this way means that the writing side
effectly sits in a tight write loop and doesn't have to wait for input.
Similarly for the input side. It is this waiting that slows down other
reblocking processes, like dd.
I run an archive and need to write large chunks out to tape regularly
with an ethernet in the way. Using 'buffer' in a command like:
tar cvf - stuff | rsh somebox "buffer > /dev/rst8"
is a factor of 5 faster than the best alternative, gnu tar with its
remote tape option:
tar cvf somebox:/dev/rst8 stuff
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