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RE: Tuning, RAID5, and fragmentation

From: Boivin, Patrice J <BoivinP_at_mar.dfo-mpo.gc.ca>
Date: Mon, 26 Feb 2001 04:44:09 -0800
Message-ID: <F001.002BD0DC.20010226035026@fatcity.com>

I would try to benchmark the system to show where the bottleneck(s) is(are). Probably I/O, possibly the CPU if you are using NT RAID5 instead of a hardware solution. If your machines aren't real servers, then the disk controller will slow things down as well, in many PCs there is one controller for everything, even if you have two slots for plugging devices like hard disks. It just flip flops between the two constantly.

At least benchmarking will help get rid of the perception that "Oracle is slow".

Is this on NT? If it is RAID5 implemented at the NT level, the MS SQL Server 7 Administration Training Kit manual, p. 128 says that its disadvantage is that is "uses system processing resources". So you may be overutilizing your CPU as well.

RAID5 is good for reading data, but not for writing because the parity info has to be updated.

To avoid having to defrag or coalesce your extents, just make sure all your extents are exactly the same size within the tablespace, and that the extents are a multiple of your db_block_size. There is an Oracle paper on this concept, if you want it send me an e-mail.

I guess this isn't Oracle Enterprise Edition...

Regards,
Patrice Boivin
Systems Analyst (Oracle Certified DBA)

Systems Admin & Operations | Admin. et Exploit. des systèmes
Technology Services        | Services technologiques
Informatics Branch         | Direction de l'informatique 
Maritimes Region, DFO      | Région des Maritimes, MPO

E-Mail: boivinp_at_mar.dfo-mpo.gc.ca <mailto:boivinp_at_mar.dfo-mpo.gc.ca>

        -----Original Message-----
        From:   dana mn [SMTP:danamn2000_at_yahoo.com]
        Sent:   Sunday, February 25, 2001 6:20 PM
        To:     Multiple recipients of list ORACLE-L
        Subject:        Tuning, RAID5, and fragmentation


        Presuming a DBA is forced to use RAID5, what elements of tuning
become
        irrelevant? (in the sense that if you're stuck with RAID5, warts and
        all, then trying to tune X, Y, and Z would be a waste of time /
        ineffective).

        Load balancing files would be one thing.. no way to put indexes and
        tables on different disks (ditto redo log file members, etc) with
one
        massive RAID5 volume.

        What about fragmentation and coalescing? Are these still a concern
for
        tablespaces located on RAID5 volumes?

        Has anyone written an article about Oracle and "living with RAID5"?
I'm
        finding that a customer has several Oracle databases on systems with
        nothing else but RAID5 storage for everything.


        Thanks very much.

         - Dana



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Author: Boivin, Patrice J
  INET: BoivinP_at_mar.dfo-mpo.gc.ca
Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists

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To REMOVE yourself from this mailing list, send an E-Mail message
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