pmemcachesize Attribute

Purpose

The pmemcachesize attribute defines a hard limit for space usage in the persistent memory (PMEM) cache. The limit cannot be exceeded, even if the cache is not full.

Note:

This attribute applies to Oracle Exadata System Software releases before 23.1.0. Otherwise, see xrmemcachesize Attribute.

Syntax

 ALTER IORMPLAN 
   dbplan=(( name=db_name, ... pmemcachesize=number ... ) ... )

Usage Notes

You specify the value for pmemcachesize in bytes. You can also use the suffixes M (megabytes), G (gigabytes), or T (terabytes) to specify larger values. For example, 300M, 150G, or 1T.
The value for pmemcachesize must be at least 4 MB.
The pmemcachelimit and pmemcachesize attributes cannot be specified in the same directive.
The value for pmemcachesize cannot be smaller than pmemcachemin, if it is specified.
In an IORM plan, if the size of the PMEM cache can accommodate all of the pmemcachemin and pmemcachesize allocations, then each pmemcachesize definition represents a guaranteed space allocation.

However, you can use the pmemcachesize attribute to over-provision space in the PMEM cache. Consequently, if the PMEM cache size cannot accommodate all of the pmemcachemin and pmemcachesize allocations, then only pmemcachemin is guaranteed.