Solaris ufs to raw w/ oracle question

Tue, 4 Feb 2003 16:28:23 -0500

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> third, convince DBA's boss that raw isn't going to
> provide much better performance in today's world, and
> this is a silly idea. 

Amen!  There is exactly one reason to use raw.  That is, the elimination of
the double-buffering the Operating System does in memory to reduce the
number of disk accesses.  Oracle ignores the buffer in memory (it doesn't
trust it).  Therefore, this extra memory copy is wasted.

This same thing can be accomplished on UFS in Solaris 2.6 and above by
mounting your filesystems with the "forcedirectio" option.  See the manpage
for mount_ufs.

Reasons not to use raw:
1. can't backup files to tape
2. can't copy or move files
3. easy to forget a partition is used for raw and use it for some other
purpose, thus destroying the data
4. can't use many oracle tools that depend on files

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<TITLE>RE: Solaris ufs to raw w/ oracle question</TITLE>
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&gt; third, convince DBA's boss that raw isn't going =
to
 &gt; provide much better performance in today's =
world, and
 &gt; this is a silly idea.

<P><FONT SIZE=3D2>Amen!&nbsp; There is exactly one reason to use =
raw.&nbsp; That is, the elimination of the double-buffering the =
Operating System does in memory to reduce the number of disk =
accesses.&nbsp; Oracle ignores the buffer in memory (it doesn't trust =
it).&nbsp; Therefore, this extra memory copy is wasted.</FONT></P>

<P><FONT SIZE=3D2>This same thing can be accomplished on UFS in Solaris =
2.6 and above by mounting your filesystems with the =
&quot;forcedirectio&quot; option.&nbsp; See the manpage for =
mount_ufs.</FONT></P>

Reasons not to use raw:
 1. can't backup files to tape
 2. can't copy or move files
 3. easy to forget a partition is used for raw and =
use it for some other purpose, thus destroying the data
 4. can't use many oracle tools that depend on =
files

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