Re: longops vs sql

> Well, I was basing that from "Oracle SQL Tuning: Pocket Reference" by
> Mark Gurry. He claims that those times are "typical of a medium to high
> end machine"
>

I'm not sure I buy that advice. Also, one needs to take advice like that with a grain of salt as disk subsystems get faster and bottlenecks choke performance....lots of different things to consider.

To show that 300 disk I/O operations per second is not a relevant factor, consider the following snapshot of my 9.2.0.7 database on Solaris taken with Statspack:

Load Profile

~~~~~~~~~~~~                            Per Second       Per Transaction
                                    ---------------       ---------------
                   Redo size:             44,784.31              4,652.94
               Logical reads:             20,146.63              2,093.17
               Block changes:                926.25                 96.23
              Physical reads:              1,007.36                104.66
             Physical writes:                102.56                 10.66

Of course a lot of the Statspack output was snipped. But from the above, I can see over 1100 *physical* I/O's per second, and my system wasn't even that busy during this timeframe. My number is quite a factor larger than the 300 that was quoted.

I would never say that my number is representative of anyone else's expected volume. Some will be higher and others lower. There's lots to take in to consideration. How many concurrent users? How many physical disk spindles? What is the disk speed? How many controllers? Fibre Channel? SATA? iSCSI? Direct I/O or buffered? Does the disk controller perform any read-ahead functionality?

Cheers,
Brian

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Brian Peasland
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