mirror of
https://git.FreeBSD.org/ports.git
synced 2024-11-14 23:46:10 +00:00
e526d43c6e
if you ever nhave needed to do something like: tar cf - <big_dir> | rsh cat > /dev/tape then you will appreciate this. do something like tar cf - <big_dir> | buffer | rsh othersys "cat | buffer > /dev/tape" to enjoy HUGE increases in speed while your tape drive does not incessantly back/forth/stop/start.
28 lines
1.1 KiB
Plaintext
28 lines
1.1 KiB
Plaintext
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, 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
|