Re: Oracle question from a Sys. admin, re: Solaris performance

We run at least 30 instances on a sun solaris 12 processor box (400Mb processors) with 12Gb RAM. It is fairly easy to determine which instances are consuming CPU just with top and then ptree.

We use ksh shell scripts which extract both OS and database information to monitor performance quite effectively.

The trick with managing the instances is to balance memory use with physical reads. Not enough memory allocated to an instance will cause increased physical reads which impacts all other databases on the same mountpoints. But, too much memory allocated can cause excessive paging or swapping, so you need to balance this out.

I generate daily reports for every database that tell me how much cpu and how many physical reads each database consume (information comes from auditing logons at the oracle level - an absolute must in my opinion), I then tune accordingly. This method has worked quite well for our box, with IO being minimised however, available memory is now quite low which will stop any more databases being created.

tonij67_at_hotmail.com wrote:
> Hi all,
>
>
> Let me preface this by stating that I am not a DBA, so please take what
> I say with that in mind.
>
> I support several Sun systems running various versions of Oracle; 8,
> and varients of 9. We are in the process of getting them all to 9.2
> but there are still some hangers-on at 8.
>
> I have been interested in learning as much as I can about Oracle as it
> may help in supporting the hardware and OS. I have been scouring the
> net for information about performance and found asktom.oracle.com ...I
> found an article that jumped out at me, about running 4 instances of
> Oracle on a system and getting poor performance. This interested me
> because we have upwards of *50* instances on a single machine with more
> on the way. Thats not a typo, 50 as in fifty.
>
> The article I looked at basically said that supporting 4 instances
> would be a "nightmare" because you never know which instance is taking
> resources. I have a couple questions about this:
>
> - is this true? Is there really know way to determine which instance
> is using, say 99% CPU?
>
> - are we insane for having this many instances on a system? I think
> its the result of sale and marketing gone wild...
>
> TIA,
>
Received on Thu Mar 03 2005 - 18:02:43 CST