Isn't it 3 drives for data, not 6, because of the
mirroring? I agree, mirroring the extra 4 (9Gb) drives
isn't necessary because this can be accomplished via
the DB config.
Veritas is also being used on the existing array and
the sys admin seems to think that we've got extra
overhead for that on top of the hardware raid-5.
I have also been told that the controller has a 16Mb
cache on it, and it only goes to 64Mb.
-w
- Christopher Spence <cspence_at_FuelSpot.com> wrote:
> 1. depends on the stripe width, data may be on one
> or many drives, parity
> will always get written to all.
>
> 2. I believe your performance will be better; you
> have 6 drives for data,
> and 4 for archive/redo. That equates to 12 drives
> over the previous 8.
> However, you were using all eight for everything.
>
> I don't believe there is any purpose to mirror the
> four drives, I like to
> use Raid 0 or single drives for redo, and just do
> multiple members and
> archive destinations. Redo/Archive is high write
> activity, Raid 1 takes a
> small hit on write, and only benefits read
> performance. You can get the
> same redundancy using duplex destination and
> multiple members.
>
> Having redo logs and archive logs separate will
> prove to be beneficial.
>
> All and all, I think you will come up with a better
> configuration
> performance-wise.
>
> Make sure the A1000 has the 80Mb cache, and has the
> latest firmware, as it
> there are a lot of buggy A1000's out there that
> cause corruption if they are
> saturated.
>
> "Do not criticize someone until you walked a mile in
> their shoes, that way
> when you criticize them, you are a mile a way and
> have their shoes."
>
> Christopher R. Spence
> Oracle DBA
> Phone: (978) 322-5744
> Fax: (707) 885-2275
>
> Fuelspot
> 73 Princeton Street
> North, Chelmsford 01863
>
>
>
> -----Original Message-----
> Sent: Friday, September 21, 2001 10:15 AM
> To: Multiple recipients of list ORACLE-L
>
> Hi,
>
> I'm encuntering a relatively high iowait percentage
> when my hot backups are running. The platform is Sun
> (E420 2cpu running SunOS 5.7) with an A1000 disk
> array
> (8 9Gb drives, hardware Raid-5). The array is one
> volume and all DB components (redo, archive, data,
> index, system, etc.) are on the same volume except
> for
> the binaries. The database is not large, only ~8Gb
> in
> size and the transactional volume is not much
> either.
> However, when the backups run, the iowait according
> to
> 'top' hovers between 50-70% which causes our
> application to time-out via Web Logic 6.0.
>
> The developers can't explain why the timeouts are
> occurring (WLS 6.0 is a new upgrade from 5.1). The
> SysAdmin isn't much help either.
>
> I have an opportunity to rebuild the database on
> another machine and use RAID 1+0 -- the thought
> being
> that we are choking ourselves with Raid-5 when the
> hot
> backups are performing the cp's (copies) and then
> the
> files are compressed.
>
> My first question is, how is the data distributed
> across the drives in my Raid-5 configuration? Is
> each
> disk being filled contiguously in series or is the
> data being spread around in a pseudo-striping
> manner?
>
> My second question/dilema is, the new array (another
> A1000) will have 6 18Gb drives and with Raid 1+0
> that
> shrinks to 3 drives of usable space for everything
> except redo and archive. 4 9Gb drives will be added
> in
> two mirrored sets, one for redo and the other for
> archive. I'm afraid that I will see worse I/O
> performance with the new array because it has so
> fewer
> physical drives, thus eliminating the benefit of not
> having to write the parity info.
>
> Do you concur? Knowing the two arrays I have to work
> with, which would be the better configuration?
>
> Any suggestions, recommendations would VERY much be
> appreciated.
>
> Thanks again for the feedback.
> -w
>
> __________________________________________________
> Terrorist Attacks on U.S. - How can you help?
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> Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> --
> Author: Walter K
> INET: alden14004_at_yahoo.com
>
> Fat City Network Services -- (858) 538-5051 FAX:
> (858) 538-5051
> San Diego, California -- Public Internet
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> To REMOVE yourself from this mailing list, send an
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> --
> Author: Christopher Spence
> INET: cspence_at_FuelSpot.com
>
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Terrorist Attacks on U.S. - How can you help?
Donate cash, emergency relief information
http://dailynews.yahoo.com/fc/US/Emergency_Information/
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Walter K
INET: alden14004_at_yahoo.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
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Received on Fri Sep 21 2001 - 10:05:28 CDT
