Once the
Then, the kernel memory on the system board to be deleted is copied into memory on the selected
Note – If the address space of a system board is renamed by a
(2) User Memory Board
A user memory board is a system board on which no kernel memory is loaded. Before deleting user memory, the system attempts to swap out the physical pages to the swap area. Sufficient swap space must be available for this operation to succeed.
(2.1) Locked Pages and ISM Pages
Some user pages are locked into memory and cannot be swapped out. These pages receive special treatment by DR.
Intimate Shared Memory (ISM) pages are special user pages which are shared by all processes. ISM pages are permanently locked and cannot be swapped out as memory pages. ISM is usually used by Data Base Management System (DBMS) software to achieve better performance.
Although locked pages cannot be swapped out, the system automatically moves them to the memory on another system board to avoid any problem concerning the pages. Note, however, that the deletion of user memory fails if there is not sufficient free memory size on the remaining system boards to hold the relocated pages.
Although such moving of memory (called save processing) requires a certain length of time, system operations can continue during save processing because it is executed as a background task.
Note – The Dynamic Intimate Shared Memory (DISM) is a feature that allows applications to dynamically resize their ISM segments. Some applications use RCM scripts to resize their DISM segments to assist DR. See the Solaris man page for rcmscript(4).