How To Tell If There Is An OS Memory Shortage And What To Do About It

• How do I know? • What tools should I use? • What do the numbers mean? •

An OS memory shortage can cause bizarre and intense performance situations. In this video seminar we will explore how Oracle uses memory, different ways to tell if there is a memory shortage, how this affects Oracle performance and what to do if there is a problem.

First Craig will explain how the operating system manages memory, including how to tell how much memory a process is truly consuming. Then he will introduce the OS monitoring tools we will use such as vmstat, iostat, top and sar. Craig will also monitor Oracle SQL statement execution throughput.

Then the fun starts! Using the simple "eatMyRam" program, Craig will slowly increase memory usage, and we will watch what happens using the tools he previously introduced. Watching how a memory shortage affects CPU utilization, the IO subsystem as well as Oracle processes and throughput will leave an immediate and lasting impression. As you will see, a memory bottleneck (excuse me, memory pressure) can cause some truly strange performance behavior.

If monitoring and understanding OS memory has been a mystery, then this seminar is for you!

What You Will Learn

  • How to determine if there is a memory bottleneck
  • How Oracle processes consume OS memory
  • The differences between private, shared and shared segment memory
  • The differences between real and virtual memory
  • Why Linux Huge Pages are awesome
  • How to use top, vmstat, sar and iostat to diagnose OS memory
  • What your options are once you know there is a memory issue
  • How Craig uses all the OS tools - you can watch him in action!
  • How the OS tools output looks as memory is slowly consumed - watch it happen


  • Introduction - What This Seminar Is All About
  • Focus On SGA Memory
  • Detailing Shared Memory
  • Focus On Process Memory
  • Detailing Process Memory
  • When All Is Good - Monitoring OS Memory
  • When All Is Bad - Monitoring OS Memory
  • OK... What Now?

Seminar Videos