./misc/buffer, Buffer sporadic binary I/O for faster tape use

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Branch: pkgsrc-2011Q2, Version: 1.17, Package name: buffer-1.17, Maintainer: pkgsrc-users

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 Free/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

SHA1: 88201f677485880cd508430015b7ce7d9663b6e7
RMD160: c7f87873f8f74b900609ef495ebabc8596729fb8
Filesize: 16.729 KB

Version history: (Expand)