Feb 11, 2009 
Since 9i, Oracle has included a feature to dynamically resize the SGA of the database when needed, without the need to restart the database. It utilizes Solaris “Dynamic Intimate Shared Memory” (DISM) to accomplish this.
DISM provides dynamically resizable shared memory. Any process that uses a DISM segment can lock and unlock parts of a memory segment, and by doing so, the application can dynamically adjust to the addition (or removal) of physical memory from a server.
In the initial releases of Solaris 10, DISM was unavailable within Solaris Zones, because the ability for processes to lock memory segments was not available. If you do try to run Oracle with DISM in Zones before 11/06, you’ll see completely awful database performance (I’ve seen it). The fix for this was to disable DISM in Oracle, by setting the Oracle parameters sga_max_size and sga_target to the same value, so the SGA would not resize at all.
Solaris 10 update 3 (11/06) introduced a new zone privilege: proc_lock_memory, which gives processes within the zone the ability to lock memory segments. So DISM will now work if this privilege is enabled. To enable it, just turn it on in the zone config and reboot the zone:
# zonecfg -z oraclezone
zonecfg:oraclezone> set limitpriv=default,proc_lock_memory
zonecfg:oraclezone> commit
zonecfg:oraclezone> exit
# zoneadm -z oraclezone reboot
If you see an error after the “set limitpriv” line when you try, make sure you have Solaris 11/06 or later (or the patched equivilant).
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