Databases Reference
In-Depth Information
As suggested, to change the maximum memory size, we need to restart the database.
Please note that Automatic Memory Management may not be
optimal for every application; it should not be used on Linux
systems with hugepages and with Oracle MultiThreaded Server.
When setting this parameter, using Oracle Enterprise Manager or the
ALTER
SYSTEM
command, never exceed the limit of available physical memory, to avoid paging and swapping
at the Operating System level.
Paging occurs when a process needs a block of memory (a page) that is not available in real
memory but in virtual memory (on disk). The OS needs to read the requested page from disk
to memory, writing the replaced memory page to virtual memory on disk.
Swapping is a process similar to paging, which involves all the memory of a process. Swapping
arises when there are too many processes running in memory.
Both paging and swapping should be avoided to achieve best performance. On the same
operating system, we can lock the allocation of SGA in real memory, avoiding the paging of
SGA memory blocks to disk. In step 8, we verify whether our SGA is locked in the memory by
querying the
LOCK_SGA
parameter, as shown in the following screenshot:
Don't set the
LOCK_SGA
parameter to
TRUE
on Solaris platform in
the server parameter file; it will not allow Oracle 11
g
database to
function. See the documentation at the following site:
http://download.oracle.com/docs/cd/E18283_01/
server.112/e10839/appe_sol.htm
