Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!ukma!rutgers!bellcore!texbell!sugar!karl
From: karl@sugar.uu.net (Karl Lehenbauer)
Newsgroups: comp.unix.microport
Subject: Re: Efficient tape I/O with 386/ix; How??
Summary: -C is the key
Keywords: streaming tape interactive slow
Message-ID: <3088@sugar.uu.net>
Date: 12 Dec 88 23:36:52 GMT
References: <317@focsys.UUCP> <276@uport.UUCP>
Organization: Sugar Land Unix - Houston, TX
Lines: 22

> In article <317@focsys.UUCP> larry@focsys.UUCP (Larry Williamson) writes:
> >Streaming tape I/O with 386/ix seems to be rather slow.
 
In article <276@uport.UUCP>, plocher@uport.UUCP (John Plocher) writes:
(lots deleted)
> 	  -Cbuffersize	Use an output buffer of buffersize

I have found this to be the key to streamer performance, much moreso than
-B.  It works on Bell Tech, too.  I use:

	find ... | cpio -ocvC 1024000 >/dev/tape

...to allocate a meg for tape buffers.  Even with a lot less it still helps
tremendously.  What'll happen is the system will fill the buffer 'til it's
full, then cpio'll write it out in one long stream.  Note that you probably
want to do this with little or no other activity as the state of files that
are being written to at the time they're backed up makes it possible that the
backups won't be any good for those files.
-- 
-- "We've been following your progress with considerable interest, not to say
-- contempt."  -- Zaphod Beeblebrox IV
-- uunet!sugar!karl, Unix BBS (713) 438-5018