RE: Using NetApp Filers for a DWH
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 4 Aug 2004 21:54:01 -0400
Just curious -- was the 10g using ASM or ASSM? I'm wondering what
statistically distributed data might do to precisely that test. Plus, Baarf.
mwf
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Mogens Norgaard
Sent: Wednesday, August 04, 2004 7:54 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Using NetApp Filers for a DWH
I like the NetApp guys, etc. But it is really RAID-4 (no kidding), so
perhaps that might explain one or two things? Just guessing...
Mogens
Richmond Shee wrote:
> For your second question: The WAFL technology can have a disastrous effect
on full table scans and fast full scans in Oracle10g. You can create this
simple mouse trap:-
>
> 1. Create a table and load a bunch of data.
> 2. Flush the buffer cache.
> 3. Enable 10046 at level 8 for the session.
> 4. set timing on
> 5. set db_file_multiblock_read_count = 16
> 6. perform a full table scan against the table. (this is your baseline)
> 7. exit
> 8. login again
> 9. run a procedure that updates the 1st row of every other block (i.e. odd
or even blocks)
> 10. repeat steps 2 to 6. Note the elapsed times and compare the two trace
files.
>
> According to my tests in Oracle10g, many db file sequential read events
showed up in the trace file after the update. I have seen as much as 89%
degradation in performance. NetApp blamed this on Oracle as a 10g bug.
Oracle kinda admitting it, but until now there is no resolution. However,
when the same test was ran in Oracle 9.2.0.4 it didn't produce this problem.
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