Different types of Shared Memory available in Solaris

Different types of Shared Memory available in Solaris

1) Shared Memory (SHM)

-basic anonymous shared memory

-also called Pageable Shared Memory

-pages can be swapped out during memory shortages which affects the application performance

2) Intimate Shared Memory (ISM)

-is used by default in Solaris

-cannot be dynamically resized

-if you want to modify (e.g. resize) a segment you must restart the processes

-does not need swap space

-segments are automatically locked by the Solaris kernel

3) Dynamic Intimate Shared Memory (DISM)

-allows shared memory segments to be adjusted dynamically (resized or relocated) (e.g. SGA can be resized) - no restart of the processes necessary

-shared memory segments can be locked by the applications by using mlock(3C)

-kernel virtual-to-physical memory address translation structures are shared between processes that attach to the DISM segment, saving kernel memory and CPU time

-needs swap space as it makes reservations on it

4) Optimized Shared Memory (OSM)

-the most recommended shared memory

-provides similar benefits as DISM but without some of the requirements of DISM

Reference metalink Doc ID 1010818.1