Linux – What parameters should be modified after upgrading RAM memory in Oracle server

The error just means that the shared_pool ran out of free space. This can be caused by many things, mostly application related. Make sure your shared_pool has a minimum size needed to run your application. Sometimes it helps to increase the shared_pool_reserved_size so larger objects can be loaded in there.

The output of free includes caches and buffers, and a lot of people fall into the trap of thinking that their memory is used while it is not. Visit this site for explanation: http://www.linuxatemyram.com/

On the other hand though, yes, Oracle can definitely use more memory than configured with the memory_max_target parameter. Parameters, such as memory_max_target, memory_max_size limit the size of the SGA only. Prior to 12c, PGA could not be limited, even though there is the hidden parameter _pga_max_size. That parameter limits the PGA size per session, but it does not account for all kinds of allocations, thus even 1 "rouge" session can eat up all the memory of the database server.

Starting with 12c, there is the parameter pga_aggregate_limit, which is a real hard limit for the PGA.

References:

• Using Automatic Memory Management (Oracle Docs 11g)
• 6.3 Using Automatic Memory Management (Oracle Docs 12c)
• 6.4.4 Using Automatic PGA Memory Management (Oracle Docs 12c)