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Breaking down the VDI disaster recovery process: VHD backup and more

The more virtual desktops you have, the more complicated the VDI disaster recovery process gets. Make sure you back up virtual hard drives often to ease DR for VDI.

One of the benefits of virtual desktop infrastructure is that virtual desktops tend to be easier to back up and migrate to new hardware when a failure occurs. The VDI disaster recovery process all starts with VDI backup, but there are a few different components you need to store and protect.

Backing up virtual hard drives
Backing up virtual desktop infrastructure (VDI) begins with the virtual hard disks (VHDs). The VDI disaster recovery process will go smoothly if you have up-to-date backups that are easy to retrieve. First, ask yourself: Are the actual VHDs stored on a storage area network (SAN) or are they stored locally on the host server?

More on VDI disaster recovery and backup:

Creating a simple VDI backup plan

How VMware snapshots work

VM snapshot backup process explained

If you use a SAN, you can back up VHDs as part of a normal backup process or using snapshots. However, a snapshot or backup is usually only as good as the last time the VHD was mounted, meaning the most current or recent information can sometimes be lost. And if you let end users personalize their virtual desktops, that makes the VDI disaster recovery process even more difficult.

Some VHDs store only static information such as the operating system and applications, but with personalized virtual desktops, end users can store data on the VHD, modify settings, install applications, store bookmarks and so forth. For a solid VDI disaster recovery plan, you need to back up these VHDs more often and may need to support real-time snapshots, where active VHDs can be backed up even while they're in use.

If VHDs are stored on the end point, you can use synchronization technology to store duplicates in the data center, or the end user can use an imaging backup product to back up of the VHD locally. Your VDI disaster recovery plan all comes down to the level of preparedness needed, the VDI backup resources available and the acceptable downtime you can have in your infrastructure.

Protecting host servers
Backing up VHDs and the associated VDI setup is only one part of a VDI disaster recovery plan. Administrators also need to consider where the virtual desktop actually runs. With large VDI, the actual data processing takes place on a server in the data center, and the end point just acts as a terminal, synchronizing screen updates and user input activities with the virtual machine on the host server.

That means you have to protect host servers as part of your VDI disaster recovery strategy, which in turn protects the virtual machines hosted on the server. To do so, you can use failover technology, where virtual sessions are automatically rerouted to another server in the data center after a disaster. However, that normally requires additional software and extensive planning.

Plus, failover often falls under business continuity planning and procedures. If a failover capability is already in place for business continuity, you probably won't have to incorporate additional support for VDI disaster recovery. What's more, many VDI backup and management products include a failover capability, which you can customize to your particular implementation.

Frank Ohlhorst
is an IT journalist who has also served as a network administrator and applications programmer before forming his own computer consulting firm.

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Has anyone heard of (or been involved in) using VHD as a business Continuity tool for work area recovery? I’m trying to understand how/if that could work.