Re: lacing redo logs on Raw Devices instea dof cooked File Systes,

Sybrand Bakker <gooiditweg_at_sybrandb.verwijderdit.demon.nl> wrote in message news:<oc8jl01s5qlverodvo6r1okege07uepeb1_at_4ax.com>...
> On 28 Sep 2004 08:12:57 -0700, premmehrotra_at_hotmail.com (Prem K
> Mehrotra) wrote:
>
> >I will be upgrading a database from Oracle8i to Oracle9i on HP UNIX.
> >Application tuning has already been done within the constraints that
> >it is an application bought from another company. It is single
> >instance database (i.e., no RAC). We will also be recreating Oracle9i
> >database and doing export/import from old to new and then applying
> >application level schema changes.
> >
> >Our application/database is clearly disk bound. We are using SAN. All
> >our file systems are cooked.
> >
> >I have read discussions on raw vs cooked on Oracle web sites as well
> >as in this forum. I am looking into moving only redo logs from cooked
> >file system to raw devices. Every time, I read about raw it clearly
> >bypasses UNIX buffer so should have some performance improvements. We
> >have 3 redo logs of 10K size. On the average every 3 minute a redo log
> >switch is made.
> >
> >I would think that there will be some performance improvement in gong
> >to raw devices. Since our database configuration for redo logs is
> >fixed (i.e., we do not expect to increase size of redo logs or number
> >of redo logs), once we set raw devices for redo logs, we are done.
> >Even if I get 5 to 10 performance improvement, I will prefer to use
> >raw devices.
> >
> >Does any one see any problem in using raw devices for redo logs only?
> >
> >Thanks a lot,
> >
> >Prem
>
> The performance improvement is more likely with setting a proper redo
> log file size. 10k is just clearly too small nowadays and you are
> switching too often. Oracle recommends an interval of 15 minutes
> between switches.
> Increasing the size of the online redo logs is almost one of the first
> things I do, when we take over a database from a third party.
> My *minimum* redo logs are 5M.
> I would first create proper online redo logs and then consider putting
> them on raw.

Sorry, I had made a mistake, my redo log sizes are 10M and not 10K, so I stll want to know whether using raw devices will be beneficial.

Thanks,
Prem Received on Tue Sep 28 2004 - 16:33:30 CDT