On 4/12/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
[EMAIL PROTECTED] wrote on 04/12/2007 04:47:06 PM:
> I time mkfile'ing a 1 gb file on ufs and copying it, then did the same
> thing on each zfs partition. Then I took snapshots, copied files, more
> snapshots, keeping timings all the way. I could find no appreciable
> performance hit.
>
> Is this a sufficient, valid test?
>
I believe mkfile is creating the file padded with zeros; and that ZFS has
short-curcuts to avoid storing actual data for such empty files. That
would lead me to believe that this is an invalid test.
-Wade
You can get around this concern with
dd if=/dev/urandom of=/tmp/1meg bs=512 count=2048
i=0 ; while [ $i -lt 1024 ] ; do cat /tmp/1meg ; i=`expr $i + 1` ;
done > /zfs/1gig
A smallish block size was chosen in the dd command because
/dev/*random doesn't allow huge blocks to be read. I forget what the
cut-off is, but 512 bytes at a time should be fine.
Mike
--
Mike Gerdts
http://mgerdts.blogspot.com/
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