[oracle-l] Re: Help With Veritas and my search for the Holy "I/O" Grail (testing with the tool from www.iozone.org)
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Sun, 25 Jan 2004 12:00:57 -0000
I haven't tried running iozone, so I don't know
what the default output looks like so this question
may be irrelevant, but are you checking the O_SYNC
figures against Oracle's performance (iozone option -o) ?
If not, then you're not comparing like with like.
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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who can answer the questions, but the
person who can question the answers -- T. Schick Jr
Next public appearances:
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Three-day seminar:
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The Co-operative Oracle Users' FAQ
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----- Original Message -----
From: <Brian_P_MacLean@xxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Sunday, January 25, 2004 12:29 AM
Subject: [oracle-l] Help With Veritas and my search for the Holy "I/O" Grail
(testing with the tool from www.iozone.org)
We have been trying to squeak out a little bit more bandwidth from our disk
sub-system. I have been doing benchmarks using the tool from
http://www.iozone.org. The command I use for the basic baseline test is
"iozone -Rab base.wks" which in effect takes all system default values to
do the reads/writes. I then test with the command "iozone -IRab
vx_direct.wks" which now forces the reads/writes to direct I/O by issuing
the command "ioctl(fd,VX_SETCACHE,VX_DIRECT);" in the .c program. When we
compare the performance of the base to the direct timings it's like "WOW,
Where have you been all my life".
So now we are puzzled as to just how in the 'el do we get Oracle to use the
direct option. We have read the Veritas manuals and combed several pages
on www.ixora.com.au (Steve Adam's site). The mount options/combinations we
have tried are "mincache=direct,convosync=direct" and
"convosync=direct,mincache=dsync". The base line testing with iozone is
between 50 and 100 percent slower with either of these mount options in
place. Running iozone with the "-I" (vx_direct enabled) continues to
scream regardless of what we do to the mount points.
So now, WTF do I do.
PS: The first person who suggests raw disk or QIO has to find me a
shrubbery)
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