Re: Oracle Parallel Server

In article <8q81nq$36m$1_at_newsg3.svr.pol.co.uk>,   "Dave Leather" <david.leather_at_energis-squared.com> wrote:
> Thanks Mark,
> I didn't intend to use autoextend, it was just a query. But the
 question
> about control files still stands. How large should the control file
 device
> be given that they can grow ( to quite a size, the ref says 20000
 oracle
> blocks ).
>
> Dave Leather
>
> "Mark D Powell" <markp7832_at_my-deja.com> wrote in message
> news:8q7qvi$gpe$1_at_nnrp1.deja.com...
> > In article <8q7l6q$vps$1_at_newsg1.svr.pol.co.uk>,
> > "Dave Leather" <david.leather_at_energis-squared.com> wrote:
> > > All,
> > >
> > > When you implement raw devices ( as you must for OPS),how does the
> > > autoextend feature happen, is is disabled for raw dev's . Also
 control files
> > > grow, what should be allocated to manage the growth , or is the
 growth
> > > different in OPS ?
> > > ( if you have any good references for OPS could you let me have
 them )
> > >
> > > Thanks in advance
> > >
> > > Dave Leather
> > >
> > >
> > I would not attempt to use auto-extend with OPS and raw
 partitions. We
> > run OPS on raw partitions and have never tried auto-extend. Since
 raw
> > partitions are fixed in size at creation it makes no sense to
 allocate
> > less than the entire partition. I would think that it would work as
> > long as the rdbms did not try to extend past the partition
 boundries,
> > but I would hope that Oracle is smart enough not to allow auto-
 extend
> > on raw partitions. Post if you find out it works.
> > --
> > Mark D. Powell -- The only advice that counts is the advice that
> > you follow so follow your own advice --
> >

Well, if you chosen Oracle Block size is 8K then 20,000 blocks would be about 160M if my mental math is correct. Plus you should leave room for future growth needed by the next release.

The more I think about it the more it seems that I have read something on how to size a control file. I though maybe I could use v$controlfile_record_section to get an idea, but it is way short.

DDC1> select sum(record_size * records_total)   2 from v$controlfile_record_section
  3 /

SUM(RECORD_SIZE*RECORDS_TOTAL)

                       1178830

If you know how many v$log_history entries you plan to keep, plus how many database files you plan to allow for, the number of redo logs members, and the space per record they require you should be able to make a decent guess. But again I seem to be coming up way short as 1024 files X 255 bytes per file name is only 255K. Even doubling it for the history and adding overhead of 255 bytes per row we are only at a megabyte.

You also have to account for rman if you plan on using it. There is an init.ora parameter to control how many days/runs of information it retains in the control file that can help limit it consumption.

This is a really good question: how do you estimate the control file size?

--
Mark D. Powell  -- The only advice that counts is the advice that
 you follow so follow your own advice --


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