Re: Maximum Oracle instances on a Server?

On Tue, 26 Feb 2002 23:53:23 GMT, damorgan <dan.morgan_at_ci.seattle.wa.us> wrote:

>I was expecting that argment. So what happens when your operating system goes
>South? Or the hard disks? Or the disk drive controller?
>
>Safety dictates one application per instance and one instance per platform.
>And a stand-by database replicating the data located at least 1,000 miles away.
>Anything less is a compromise.
>
>Pick your compromise.
>
>Daniel Morgan
>
>
>
>Ed Stevens wrote:
>
>> On Tue, 26 Feb 2002 21:23:00 GMT, damorgan <dan.morgan_at_ci.seattle.wa.us> wrote:
>>
>> >I would say one. Not that you can't put more on ... but I've never understood
>> >the reason for creating another instance with its own SGA when you can just as
>> >easily create another schema with its own tablespaces.
>> >
>> <SNIP>
>>
>> Uh, so that if your inventory 'database' (schema) goes south, you don't have to
>> bring down your payroll 'database' (schema) to fix it?
>> --
>> Ed Stevens
>> (Opinions expressed do not necessarily represent those of my employer.)
>

Yes, pick your compromise. All engineering decisions are compromises. I liken this to the federally mandated 5mph impact resistence bumper. Such a bumper is more expensive and thus drives up the cost of the car. And at collisions of greater than 5mph, still fails and thus drives up the cost of repairs. So is the 5mph bumper worth the cost? Only to the degree that most collisions occur at less than 5mph.

In the case of Oracle db's, if the cost of a loss of availability is expensive enough, then it will justify the cost of 1 db per box, with a failover, replicated box at the other end of a 1000-mile long leased line. Other situations may make the business case for 1 app per box but without the expense of geographically separated failover. However, if the business case justifies putting data for two different apps on the same box in the first place, then there is NO additional cost to putting them under two different sids and giving them at least THAT degree of isolation from each other.

YMMV.

--
Ed Stevens
(Opinions expressed do not necessarily represent those of my employer.)