14.4. Checking Shared Memory Before Starting Oracle Databases
It is very important to always check the shared memory segments before starting an instance. An abandoned shared memory segment, from an instance crash for example, is not removed, it will remain allocated in the Big Pages or Huge Pages pool. This could mean that new allocated shared memory segments for the new instance SGA will not fit into the Big Pages or Huge Pages pool. For more information on removing shared memory, see Section 7.4, “Removing Shared Memory”.