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Also challenging are the different types of recovery: backing up and recovering the entire VM as a file, or backing up and recovering single files. To back up and recover the entire VM, you "copy it block by block, disk to disk and capture the VM in a specific state," says Oglesby. "Here, you have to restore the entire VM as a whole."
To back up and recover individual files you "do a file-level backup within the VM using a normal agent or VCB, like a traditional backup. In this case, you can restore a single file easily but can't bring the entire VM server back online easily," he continues. You have to recover the VM piece by piece.
Virtualization is essentially file-oriented; the VM consists of one or two encapsulated files. Restoring individual files remains a challenge. It's easy to back up and restore the entire VM. Restoring individual files isn't straightforward and, depending on the backup tools involved, may be quite
| cumbersome and involve restoring the entire VMware Disk file (VMDK).
"Everybody wants to rapidly back up at both the granular [file] and virtual machine level," says Mainland Information Systems' D'Costa. With VMware as it's configured today, that's not possible. "Right now you have to choose one or the other," he says. Granular backup means you can recover individual files without restoring and mounting the entire virtual server. With machine-level backup, you recover the entire virtual server as a single VMware encapsulated file; VMDK is fast and easy if you need to recover the whole thing.
This was first published in September 2008