Monthly Archives: October 2015

Backing Up Virtual Machines Using Avamar Image-Level Backup

Avamar can backup virtual machines using guest level backup or image-level backup.

The advantages of VMware guest backup are that it allows backup administrators to leverage identical backup methods for physical and virtual machines, which reduces administrative complexity, and it provides the highest level of data deduplication, which reduces the amount of backup data across the virtual machines.

The second way to backup virtual machines is via the Avamar image-level backup. It is faster and more efficient and it also supports file level restores.

Avamar integrates with VMware VADP (vStorage API for Data Protection) to provide image level backups. Integration is achieved through the use of the Avamar VMware Image plug-in. Simply put, the VMware Image backup creates a temporary snapshot of the virtual machine, and uses a virtual machine proxy to perform the image backup.

Backup can occur while the virtual machines are powered on or off. Since the backup is handled by a proxy, CPU cycles of the target virtual machines are not used.

Avamar provides two ways for restoring virtual machine data: image restores, which can restore an entire image or selected drives; and file-level restores, which can restore specific folders or files.

However, file-level restores are only supported on Windows and Linux. In addition, it has the following limitations:

1. File-level restores are more resource intensive and are best used to restore a relatively small amounts of data. In fact, you cannot restore more than 5,000 folders or files.

2. The latest VMware Tools must be installed on the target virtual machine, in order to successfuly restore files and folders.

3. Dynamic disks, GPT disks, deduplicated NTFS, ReFS, extended partitions, bootloaders, encrypted and compressed partitions virtual disk configurations are not supported.

4. ACLs are not restored.

5. Symbolic links cannot be restored.

6. When restoring files or folders to the original virtual machine, only SCSI disks are supported; IDE disks are not supported.

If you must restore folders or files, and you ran into the limitations mentioned above, you can restore an entire image or selected drives to a temporary location (for example, a new temporary virtual machine), then copy those files and folders to the desired location following the restore.