misc/buffer 1.17nb1 NetBSD

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