SUMMARY: ZFS vs UFS - Anyone runs big Oracle DB on ZFS?

From: Stephanie C <>
Date: Mon Jul 28 2008 - 12:34:05 EDT
Thank you for all excellent responses. I really appreciate for your help.

*From: francisco roque*

We run all of our production databases on zfs, but the largest is only
about 70GB.  There are a number of steps you need to take to get better
performance for db.  Read through the entirety of the ZFS Best Practices
*and the related tuning guide:
The main changes we make are to limit the ZFS ARC and to disable cache
flushing (we use SAN disk).  We tried these changes and found that it gave
us performance similar to our previous filesystems (ufs/vxfs).

If you try zfs, be sure to test it out on a dev system and do some true perf
testing to verify that any changes you make are really effective. Depending
on the nature of your database, you may find a number of the tuneables
worthwhile, but only testing will verify this.

* *

*From: Jeff Marble*

 We had one issue with ZFS and one with contiguous blocks of memory on
our Oracle 10g server.  We are running fine now after discovering the
corrections.  We do not typically have a heavy load though.

ZFS - Oracle performs a sync write which requires that all buffers are
written do disk.  That means all cache must be flushed out to disk and
a response must be received before proceeding.  We got around this by
putting the ctl files, redo, and arch files to a separate 5GB
partition.  Performance went way up.

Large Contiguous Blocks - Sun attempted to implement a new feature
where Oracle is given large contiguous blocks of memory to work with.
The problem is that at times, the algorithm cannot find the space and
the system comes to it's knees.  It does not happen if Oracle is
brought up immediately after starting the computer, before any other
app can fragment the RAM.  We set pg_contig_disable=1 in /etc/system
and rebooted.

Run this line to stop the hunt for contiguous pages.  You should see
results in a few minutes.

echo "pg_contig_disable/W 1" | mdb -kw

Or for a more permanent resolution, put this in /etc/system and reboot.
** Disable coalescing feature
set pg_contig_disable=1

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*From: Martin Pre_laber***

perhaps that article will help you:

*From: Maciej Bliziqski***

My company is running Oracle 10g on ZFS. Our database is comparable to
300GB, and we have no performance issues. I'm only administering the
OS, so I don't know much more than that at the moment. If you have
specific questions, I can ask around.

*From: Rajiv Gunja***

Some of the production DBs at our Org has about 1.5 TB to 3 TB of Oracle
9/10 on SUN Solaris with FS = vxfs. One way we take care of performance
issues is to split the DB in to smaller pieces across different FS.

Its been many (11)years since I worked with Oracle, so not sure what
snapshot is. We use NetApps for SAN so we have daily snapshots of the FS
done on the SAN side and we also perform cold backup weekly.

*From: Dr. Udo Grabowski*
You could also create vdevs on a zfs raidz filesystem, export them
via iscsi, and then create a UFS filesystem in them with directio access
Oracle. On our MySQl database this gave a factor of 5 better performance
than an adapted (recordsize,etc.) ZFS filesystem, and we have the
checksumming and other features of ZFS still underneath

On Fri, Jul 25, 2008 at 3:59 PM, Stephanie C <> wrote:

> We are moving from HP-UX to SUN Solaris 10. We would like to configure the
> Oracle 10g DB with the ZFS file system to take advantages of this ZFS cool
> features (snapshot...). But since we have some information about Oracle 10g
> DB is having some performance issue  with ZFS file system (this information
> is not confirmed), we don't really want to take this chance. I hate to have
> two file systems (ZFS for applications data and UFS for DB) in one zone.
> When I do 'zfs snapshot', it will not snap the Oracle DB. Before making the
> decision to go or not to go with ZFS for DB, I would like to ask the experts
> on the list. Does anyone run Oracle DB (300GB data) on ZFS zone? Do you
> experience with the performance issue? Thank you.
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Received on Mon Jul 28 12:36:17 2008

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