Hello,
Does SGA_TARGET always hold/lock the required RAM, what will happen if memory pressure by OS processes.... Oracle will release the memory from SGA or SWAPPING will happen?
Ques explained in detail:
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- Say RAM=32G, SGA_TARGET=64GB, in this case we are able to start the DB (not sure why Oracle is allowing so, anyway we can ignore this question for now) and we leaving DB ideal (i.e no app or client connection, no non-default DB scheduled Job running, just to make sure SGA is ideal), now here:
1) current SGA utilization is showing 64GB (Oracle is just displaying it as 64 GB, but in actual cannot use more than ~32 GB)
2) 'free' OS command is showing that AVAILABLE memory as '0' and buff/cache memory as ~32 GB and SHARED memory as ~32 GB (i.e all RAM has been occupied by Oracle's SGA), in this scenario from where the other OS processes or PGA will use memory (again NOTE: Oracle DB is ideal, it has just almost ideal/free SGA) -> will it use SWAP or OS SHARED MEMORY will be released (which is for ideal SGA) for such processes??.. If OS SHARED MEMORY will be released then it should not start SWAPPING correct?... and if OS SHARED MEMORY will not be released, then it means SGA is locking the memory as defined in SGA_TARGET??
Thanks,
Jorden