Recommendations for tunable shmmax in preparation for Oracle10g

[Ralph Grothe]

Hi Court,

at the moment the value is set to abt. 22 GB (of 32 GB RAM), so I would think I could well leave it at that.

# kmtune -q shmmax|perl -alne 'print hex($F[1])/2**30 if $F[0] eq "shmmax"'
22


How can I find out how much memory was assigned to the old 9i DB?
In the pfile init.ora I couldn't find some sga param.
There must exist a view in the data dictionary that one can query by a simple SQL statement?

[Ralph Grothe]

Wait, I think this should suffice as a clue

# ipcs -mob|grep oracle
m 368649 0xe0377310 --rw-rw---- oracle dba 13 98275328
m 3082 0xe71d289c --rw-r----- oracle dba 797 13826273280

[Court Campbell]

Login to sqlplus and;

>show sga

That will show the sga size.

[Court Campbell]

I truly recommend that you read this:

http://orafaq.com/node/8

I believe that it will answer a lot of your questions.

[TwoProc]

Small point - but , set it just a bit bigger than db_cache_size - because this most likely is your largest piece of the SGA. The other parts of the SGA will be perfectly happy living in their own segment(s) after the buffer cache gets its own big space.

[Tim Nelson]

Duely noted Court,

I think all responses are valid and helpfull enough to help Ralph make his decision.

[Ralph Grothe]

show sga:

SQL>
Total System Global Area 1.3809E+10 bytes
Fixed Size 756808 bytes
Variable Size 1795162112 bytes
Database Buffers 1.2012E+10 bytes
Redo Buffers 1060864 bytes


which indeed is the shm seg @ ID 522 as I already have assumed:

# ipcs -mob|grep ora
m 167945 0xe0377310 --rw-rw---- oracle dba 12 98275328
m 522 0xe71d289c --rw-rw---- oracle dba 1165 13826273280