1997-10-11 23:53:59 +02:00
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This is a program designed to speed up writing tapes on remote tape
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drives. Requirements are shared memory and locks which normally
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means that these are supported in your kernel.
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2003-05-06 19:40:18 +02:00
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[for Free/NetBSD, this means you MUST have a kernel with
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1997-10-11 23:53:59 +02:00
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options SYSVSHM
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compiled in - markm]
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Buffer has been tested under SunOS 4.0.*, SunOS 4.1.*, Solarix, HP-UX 7.0,
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and Gould UTX 2.1A (sv universe).
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The program splits itself into two processes. The first process reads
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(and reblocks) from stdin into a shared memory buffer. The second
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writes from the shared memory buffer to stdout. Doing it this way
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means that the writing side effectly sits in a tight write loop and
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doesn't have to wait for input. Similarly for the input side. It is
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this waiting that slows down other reblocking processes, like dd.
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I run an archive and need to write large chunks out to tape regularly
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with an ethernet in the way. Using 'buffer' in a command like:
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tar cvf - stuff | rsh somebox "buffer > /dev/rst8"
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is a factor of 5 faster than the best alternative, gnu tar with its
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remote tape option:
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tar cvf somebox:/dev/rst8 stuff
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