VM Data Protection Primer: Comparing Data Protection Strategies for Virtual Server Environments

Server virtualization technology provides compelling business benefits by enabling companies to consolidate many physical servers into a smaller number of highly utilized servers or blade racks. In a virtual server environment, resources such as processing, application space, and storage are allocated by need, not by physical limitations. Now companies can buy and allocate computing resources in a way that increases operational flexibility, optimizes server performance and storage capacity and requires fewer administrators to manage.

However, without a well-planned backup strategy to protect a virtual server environment, the cost savings achieved can be quickly lost to increased complexity, increased risk and increased capacity requirements.

There are a variety of backup methods that can be used to protect a virtual server environment. This paper provides a framework for helping you define your data protection requirements to choose a backup strategy that best meets those requirements. 

In the world of physical servers, data protection is simple.  Each server is either a LAN client of a media server and is protected through either a LAN or SAN backup. In a virtual server (VM) environment, there is no longer a one-to-one relationship between the physical hardware and what is defined as a “server”. In addition, because VMs are easy and cost-effective to create, many virtualized data centers experience server proliferation. In these environments with many times more servers, the backup environment is significantly more complex.

Define Your Backup Requirements

Today, there is no industry standard for how to backup VM environments and there are significant trade offs to be made with every solution. Therefore, you need to start with a clear understanding of your backup requirements as well as your priorities (must-haves vs nice-to-haves). Consider the following your priority list:

• Backup performance: Start with an assessment of how well you are currently meeting your backup windows. Some methods of backing up VM environments can be I/O intensive (slowing performance) and some deduplication technologies can further slow down backups. Consider how much performance you are willing to give up for the benefits offered by your planned backup environment. Do you need to manage your I/O environment to avoid bottlenecking a given VM host?
• Restore performance: Do not assume that fast backup performance automatically means fast restores. Restoring data to a virtual server environment may be many times slower than backing it up. Determine whether you need single file recovery or will full volume restore suffice?
• Application consistency: Backup consistency may suffer when you are using a backup application with memory resident components. Consider how your backup software features and functionality will be affected.
• Added complexity: Many VM backup environments require the addition of proxy servers, intermediary backup software, and other new technologies. Weigh the cost and added complexity of these technologies against their relative value.
• Impact of backup volume growth: The larger your backup volume, the more complex and costly your backup environment is likely to be. Consider how quickly your data is growing and the impact of that growth on your backup environment. For example, can you store all of your data in a single backup system or will you be forced to divide it among multiple systems.

Understand the Tradeoffs

Client-based Backup
This backup methodology is the same as performed in the physical server world.  Each virtual machine is treated as backup client and will backup over the LAN as scheduled in the backup application.