EMC’s IT group has published a paper outlining how they deploy Oracle in a virtualized world. This paper describes 4 distinct models for consideration when deciding on making Oracle databases highly available. The paper begins by describing the journey the EMC went through as they began to virtualize their applications. The focus is primarily on Oracle databases, but the journey is virtually the same for any organization virtualizing their entire stack.
The first deployment model is by far the simplest. This model discusses virtualizing single instance Oracle databases. The benefits of virtualizing a single instance are tremendous. With VMware virtualization, you immediately get high availability. With vSphere, if the VM goes down for any reason, vSphere will automatically bring that VM back online. With vSphere 5, you can add database awareness. This awareness comes in the form of VMware GuestAppMonitor. I started a discussion of this feature in the Everything Oracle at EMC community, but basically, you can write a script to check the availability of any application or process. If this script does not complete in a predetermined time, vSphere will restart the VM and/or send out a notification. No more worries about a hung database node.
Also, VMware virtualization comes with a technology call vMotion. This feature allows an administrator to migrate a running VM from one physical ESX host to another. This movement does not require any downtime and is completely transparent to the user. This feature is also used in an automated fashion to migrate VMs from a heavily loaded ESX server to another lesser loaded one. This feature is call Distributed Resource Scheduler and allows organizations to achieve much higher physical to virtual server consolidations than other virtualization technologies.
The benefits continue with many more features and technologies to make Oracle databases run better, faster and cheaper, but I will save that for my next entry. Please take the time to check out this paper. I guarantee you will find it interesting.