title: ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist Linux-x86_64 Error: 2: No such file or directory
body: <p>I am running Oracle 11g on Linux server and one the below Database issues occurred suddenly (every 2 weeks or 3 weeks sometimes): </p>
  
  <p>Some times: 
  ORA-01034: ORACLE not available ORA-27102: out of memory Linux-x86_64 Error: 12: Cannot allocate memory Additional information: 1 Additional information: 163844 Additional information: 8 </p>
  
  <p>And last time: 
  ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist Linux-x86_64 Error: 2: No such file or directory   </p>
  
  <p>When I tried to startup database after setting up SID but I had the below error: 
  SQL> startup
  ORA-00845: MEMORY_TARGET not supported on this system</p>
  
  <p>I rebooted the server then everything is OK </p>
  
  <p>My page size: 4096
  kernel.shmall = 4294967296</p>
  
  <p>How can I prevent these issues from happening again? should I update anything in Oracle memory settings? </p>