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Date: Mon, 12 Jan 2009 12:20:46 +0100
From: Ollivier Robert <roberto@keltia.freenix.fr>
To: freebsd-hackers@freebsd.org
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Subject: Re: 3x read to write ratio on dump/restore
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According to M. Warner Losh:
> The read kBps was 3x the write kBps.  While the dump is going through
> the raw device, and the restore is going through the file system, I
> can't imagine why we'd have such a huge difference that would be utter
> consistent for the whole 15 hour run.

dump launches several processes to read the raw device and use a buffer
between them whereas restore is single process.  When copying from disk to
disk, I often use team (sysutils/team) to stream.
-- 
Ollivier ROBERT -=- FreeBSD: The Power to Serve! -=- roberto@keltia.freenix.fr
Dons / donation Ondine : http://ondine.keltia.net/