Thank you Rachel.
Jared,
here is what I meant:
select
100 * (a.value + b.value - c.value)
/ (a.value + b.value)
from v$sysstat a,
v$sysstat b,
v$sysstat c,
v$sysstat d
where a.statistic# = 37 and /* db block gets */
b.statistic# = 38 and /* consistent gets */
c.statistic# = 39 and /* physical gets */
d.statistic# = 40 /* physical writes */ ;
It had been for years "the most important thing to measure" - if the number was over 80%, everyone was happy. If I remember correctly, Oracle Education Services taught it at the advanced level of dba courses.
If anyone remembers the beginning of this tread, the issue at hand is not how to measure performance, but what are the 10 metrics one can measure. After the first note or so, there was still a plea for "the list".
To add to a discussion, which derailed from the original plea for "the list":
Good or bad performance has very little to do with ratios, numbers, importance of transactions (by the way: from whose point of view?)
Well performing system is such, that allows ALL supported by it business functions to achieve their objectives for the less possible amount of money.
If a program, which produces monthly report for shareholders is poorly written from the art of programming point of view, creates a report formatted as per specifications, including colours, ready to be delivered on time - the system is performing well. Even if that program runs 5 hours except 5 minutes, as long as it is not in a way of anything else. Computers are expensive, useless gadgets when they are not working.
In addition, managers are neither educated in technical nuances nor need to be. Somebody, maybe another dba, or an editor of an in-flight magazine has written somewhere that there are ten Oracle database parameters that should be measured.
So, to keep all parties happy, one should produce "the list", meet with users to find out what is not performing up to their expectations. When this is known, use both, common sense and "the list" to find out what and how can be changed. If anything, because many times the only acceptable to the business solution is: "learn to like it".
Amen.
grandma inka
-----Original Message-----
Sent: Wednesday, October 02, 2002 9:39 PM
To: Multiple recipients of list ORACLE-L
we're hiring a hosting company to manage and monitor our production
apps... they handed me their spreadsheet of Oracle "things" to
monitor... I finally found "wait events" on that list. Buffer cache hit
ratios were high on the list and flagged as "critical"
nuh uh, didn't have time to gently explain (with the two by four) that
that was going to be unacceptable. But I will have loads of time
tomorrow. What scares me is that this list was compiled by
"experienced" DBAs.
- Jared.Still_at_radisys.com wrote:
> Buffer Cache Hit Ratio?
>
> What's that?
>
>
>
>
>
>
> "Inka Bezdziecka" <IBezdziecka_at_cupe.ca>
> Sent by: root_at_fatcity.com
> 10/02/2002 08:03 AM
> Please respond to ORACLE-L
>
>
> To: Multiple recipients of list ORACLE-L
> <ORACLE-L_at_fatcity.com>
> cc:
> Subject: RE: Performance monitoring
>
>
> Well ...
> if you need short reports, look for:
>
> 1. waits
> 2. buffer cache hit ratio
> 3. dictionary hit ratio
> 4. library hit ratio
> 5. latches
> 6. parsing/execution ratio
> 7. data file i/o
> 8. shared pool memory distribution
> 9. session contention
> 10. session memory usage
>
> inka
>
> -----Original Message-----
> Sent: Wednesday, October 02, 2002 7:08 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Thak's Mark
>
> I agreed, but they have gotten an idea to get only couple
> "most important" measurements from db, because they don't want
> to have a huge reports with all possible statistics. Very
> understandable, but as You wrote, there isn't any absolutely top ten.
>
> In any case, I have to do this (stupid) list, so give Your best shot,
> please.
>
> t.Jorma
> Ps. I heard, that Dave Ensor from BMC, has once presented that
> kind of list?
>
> -----Original Message-----
> Sent: 02 October, 2002 12:23
> To: Multiple recipients of list ORACLE-L
>
>
> Jorma,
>
> Performance tuning is a complex subject. There really isn't a list
> of
> 10 things to watch for. Every system is different.
>
> I would (attempt to) summarize tuning by these five steps:
>
> 1.) Have a capacity/performance target in mind. If you don't know
> where you're going, how will you know if you have gotten there?
>
> 2.) Monitor your response times as load increases. Can you achieve
> your response time target at the specified load? If so, you're done,
> successful test, congratulations. If not, continue to next step.
>
> 3.) Actively monitor what's going on in the database, while it's
> happening. It's always easier to see it in real time than just
> looking
> at random StatsPack snapshots taken at 5 or 10 or 15 minute
> intervals.
> (Not that I'm saying StatsPack shouldn't be collected. I'm just
> saying
> don't rely on StatsPack as your only source of info about the
> database.) The V$ Wait Interface is your friend. If you're not
> familiar with it, go to http://www.hotsos.com/ and get Mogens
> Norgaard's
> paper, Introducing the V$ Wait Interface. Where is the database
> spending it's time? What's the bottleneck? If you identify a few
> trouble sessions, you may want to dive deeper w/ some 10046 traces at
> level 8 on specific sessions. You almost certainly do NOT want to do
> this instance wide.
>
> 4.) Once you have some indication as to what's going on in the
> database, you need to see how the system is doing overall. On most
> flavors of *nix, where I'm comfortable, sar (System Activity
> Reporter)
> is an excellent tool. Use it to determine if you have any systemwide
> CPU, memory, or I/O contention. (Other OSes almost certainly have
> similar utilities.)
>
> 5.) Address the biggest bottleneck. This is where it can't be
> summarized in a simple step. You need to understand the bottleneck,
> so
> that you can understand how to tune it. If may be latch contention.
> Depending on the latch, it could be poorly tuned SQL, or lack of bind
> variables, or simple CPU capacity limits, or a whole host of things.
> I/O contention? Could be anything from poorly designed and/or
> configured RAID array to poorly tuned SQL, or who knows what.
> Determine
> the cause of the biggest bottleneck and minimize or eliminate it.
>
>
> There you have it, Mark's Simplified Performance Tuning, in five easy
> steps! ;-)
>
> -Mark
>
>
>
> On Wed, 2002-10-02 at 02:08, Jorma.Vuorio_at_nokia.com wrote:
> > Ave !
> >
> > I like to hear Your opinion about the most importat
> > issues, what should be monitored from the database (8.1.7, SUN)
> during
> > perfomance testing. The purpose in this case, is limit the
> > monitoring to concern only about 10 most important ones.
> >
> > I have difficulties to make my mind to pick up the right ones, so
> > if You had to have made similar kind of decisions or have opinions,
> > please let me know.
> >
> > TIA
> > Jorma
> > -----------------------------------------------------------------
> > Name: Jorma Vuorio Phone: +358-9-7180 67759
> > Company: Nokia Business Infrastucture Fax: +358-9-7180 67465
> > Address: P.O.Box 321, FIN-00045 NOKIA GROUP, FINLAND
> > Internet: jorma.vuorio_at_nokia.com Mobile: +358-50-486 8043
> > -----------------------------------------------------------------
> --
> --
> Mark J. Bobak
> Oracle DBA
> mark_at_bobak.net
> "It is not enough to have a good mind. The main thing is to use it
> well."
> -- Rene Descartes
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
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> Author:
> INET: Jared.Still_at_radisys.com
>
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Received on Thu Oct 03 2002 - 10:48:38 CDT
