Virtual machines, regardless of the underlying technology (VMWare ESX; VMWare Fusion; Microsoft Hyper-V; Oracle VM Virtual Box; Parallels, to name the more common technologies in use at Cornell) present a particular problem when backing up the host system.

The EZ-Backup service recommends that the virtual disk file(s) (with extensions such as .vmdk, .pvm, .hdd) should NOT be backed up by the TSM client running on the host system. Attempts to backup these files are prone to failure (files are open/rapidly changing), and even if successfully backed up, could not provide the capability to perform file level restores. As such, the default configuration that is delivered by the EZ-Backup team for Windows and Macintosh systems excludes such files from backups.

If file-level restore capability is required for a VM, the EZ-Backup service recommends running the appropriate EZ-Backup client in the VM, backing up to its own node (so as to minimize contention possibilities with the backups of the host system).