Re: UNIX hardware sizing for multiple instances

Hi Peter,

disk space... you'll want a healthy margin here, enough to take hot backups, keep a day's worth of archived redo, etc. The other thing when buying disk nowadays is remembering that disk storage capacity (in MB) has increased dramatically faster than disk IO capacity (in MB/minute). You'll have to ensure that however much you buy, it can handle not only your storage requirements but also your IO requirements. Some SAs have been known to only format the inside 25% of each platter because of IO needs outweighing storage capacity.

physical memory... don't forget to calculate additional memory for your instance processes and background processes!

number of processors... although oracle was designed to use multiple processors (or multiple threads on NT) acting simultaneously, oracle's current pricing model encourages you to use few (or one!) very fast processors instead. My understanding is that a single very fast processor can give excellent oracle performance. Interestingly, I understand that there is a significant performance advantage to using 8MB secondary caches instead of 4MB caches, as the bulk of the active oracle executable code is then op-code cached.

Hope this helps,
Paul

---
www.pythian.com -- vallee_at_pythian.com -- 877-PYTHIAN
Smarter than adding another team member, Pythian has new services for
supplementing DBAs: get our help with monitoring, 24x7 on-call, daily
verifications, storage management, performance and more.


----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
Sent: Monday, April 15, 2002 3:18 PM


My group has requirement to run three, possibly
four, instances of Oracle (8.1.7, most likely) on a UNIX server


(AIX, if that matters).  We are considering separate instances

because the software comes from three different vendors.
The fourth database will be ours and may be able to run on one of
the other three instances.

For determining the size of the server we are using the following
guidelines:

disk space = amount needed for the o/s (including virtual memory) +
             Oracle software +
             data files

physical memory = amount needed for the o/s +
                  total sizes of the SGA for all instances

number of processors = at least two

processor speed = somewhere in the middle range

We are assuming that the processors do not have to be blindingly fast for
a database server.  We are also assuming that the number of processors
is more important than their speed.

So my questions are:

1.  Are we on the right track with the physical memory calculation?

2.  Should we figure in an additional amount of memory for each dedicated
server process,
assuming that we will not be using MTS?

3.  What criteria should we use to determine number of processors?

4.  Any other comments about our calculations and assumptions?

Thanks,

Peter Schauss
Northrop Grumman Corporation
516-346-3148
schaupe_at_mail.northgrum.com
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Schauss, Peter
  INET: SCHAUPE_at_mail.northgrum.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L


(or the name of mailing list you want to be removed from).  You may

also send the HELP command for other information (like subscribing).




-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Paul Vallee
  INET: dbalist_at_pythian.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L


(or the name of mailing list you want to be removed from).  You may

also send the HELP command for other information (like subscribing).