As with many Oracle parameters ... it depends. On your OS and your Oracle version.

Oracle 8i and below: 4gb max.
Oracle 9i and above: maxint-1 (2^64-1 on 64-bit machines, 2^32-1 on 32-bit machines).

IF you're on a 32-bit system, Oracle recommends no larger than 4gb generally.

Windows NT would not address anything larger than 4gb and wouldn't let any one
process have anything more than 3gb . I believe this is fixed in XP/2000.

If you're on a 64-bit system, then you can go as high as about 70% of physical
ram before Oracle gets antsy. In fact, dbca defaults to using 70% of the
known ram if you take memory defaults during installation.

70% is a good value, assuming there's nothing else on the machine, as you'd
suspect. Otherwise, adjust down accordingly.

Don't forget to give the machine lots of swap space, if you allocate some
huge amount of shared memory for Oracle's use.

Boss

>
> What are the guidelines for setting value of SHMMAX.
>
> I remember reading something like 50 to 60% of main memory.
>
> Would it also depend on
> * Whether other applications / processes are running on the server or not?
>
> Would it be always according to this guidelines even if the RAM is 256 MB or
> 16 GB?
>
> Regards,
>
> +Rahul
>
>
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