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Date:      Tue, 2 Oct 2001 17:59:48 +0200 (CEST)
From:      Egervary Gergely <mauzi@faber.poli.hu>
To:        <freebsd-hackers@freebsd.org>
Subject:   newbie question: filesystem i/o
Message-ID:  <Pine.LNX.4.30.0110021739060.25456-100000@faber.poli.hu>

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hi hackers,

I'm quite new to FreeBSD but not in UN*X, please let me ask a question:

I wonder that the filesystem performance under FreeBSD is so great. I'm
doing disk-to-disk file copies, like ``dd if=file1 of=file2 bs=64k'' and
the performance is much better than on other unices. Other systems use
16k or 64k (or whatever MAXBSIZE is set to) chunks for sequential i/o, and
the disk seeks like an evil. On FreeBSD, the disk seeks _much_ less.

probably FreeBSD is re-blocking the (contigous?) chunks, and does i/o with
huge blocks like several megabytes? How is it done technically? Is it the
filesystem, or the VM?

could someone enlighten me please? :)

cheers,

-- mauzi


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