This post is part of the 7-part series Seven Top Benefits of Virtualizing Business Critical Applications.
Ensuring availability of your applications is difficult. Each application component must be made highly available, and operations teams often struggle with a proliferation of different clustering and availability options. The Web tier is fairly simple to protect using network load balancing, and the application tier can be clustered, but databases are typically the most difficult tier to protect. Databases can be protected using Microsoft Clustering, database mirroring, or high-end options such as Oracle RAC.
VMware provides a range of capabilities that can extend availability to 100 percent of applications including databases, without the complexity or cost of clustering. These capabilities are:
- vMotion – Move running virtual machines from one physical server to another with no impact to end users. vMotion keeps your IT environment up and running, giving you unprecedented flexibility and availability to meet the increasing demands of your business and end users.
- High Availability – Provides automated application restart in the event of host failure or OS failure within the virtual machine. It is automatically available for any application running on vSphere. VMware HA is simple and does not require OS- or app-level clustering. It is also very cost effective because it doesn’t rely on dedicated standby servers, and in many cases allows the use of lower-cost OS and application licenses.
- App-Aware High Availability – Monitors the application and if it goes down, it can be restarted. App-Aware HA will run the failover only when the application doesn’t come back up again. The underlying technology depends on the VMware HA to automatically initiate the failover. App-Aware HA is an API that allows users to plug in one of two currently available third-party App-Aware products from Symantec or Neverfail.
- Fault Tolerance – Protects any application against host failure with continuous availability, without data loss or downtime. VMware FT creates virtual machine “pairs” that run in lock step—essentially mirroring the execution state of a virtual machine. To the external world they appear as one instance (one IP address, one application)—but they are fully redundant instances.
The siloed example of availability methods shown in Figure 11 requires expensive licenses, dedicated standby infrastructure, and highly skilled staff to configure and manage. The alternative to this expensive approach is a standardized approach using vSphere technology, though some companies choose to implement both appspecific and VMware solutions running in tandem.
To prepare for availability issues affecting an entire datacenter, VMware vCenter™ Site Recovery Manager (SRM) enables datacenter teams to build, manage, and execute reliable disaster recovery plans for all applications, including business-critical apps. By taking full advantage of the encapsulation and isolation of virtual machines, SRM enables simplified automation of disaster recovery. SRM helps meet recovery time objectives, reduces costs traditionally associated with business continuance plans, and achieves low-risk and predictable results for recovery of a virtual environment.