Backing up XenServer guests to a USB drive

Sometimes, cheap and easy is the best way to go. If you're on a budget, and want to back up your XenServer guests without dedicating a physical server to the task, and you don't have a Windows CIFS share, SAN or NAS storage available, a guest VM running Alike, connected to a USB drive works in a pinch. This configuration is not an ideal solution in the long-term.

What we're going to do is connect a USB drive to the XenServer host, set up a new Windows VM to run Alike, and then run Alike off of the USB drive. Because Alike will be running on guest inside the XenServer box, it will speed up the time it takes to download your guest snapshots, since they won't be going out over the network. 

1) Plug in the USB drive to your XenServer host. It will now show up in XenCenter under "removable storage"
2) Select or Create a suitable Windows guest VM to run Alike.
3) In XenCenter, map the USB drive to the Windows guest by selecting the Storage tab of the guest, and clicking "Attach..."
4) Install Alike within the guest, choosing a directory within your mounted USB drive as the installation directory.
5) Under Settings, verify your block storage directory is on the removable drive.
6) Schedule your backup jobs as usual. (Note: Do not backup the VM running Alike using Alike.)

Now you have a portable backup solution contained on a single USB drive.  If there is a problem with your XenServer host, you can connect the USB drive to a different Windows server (virtual or physical), re-run the install on top of the existing USB installation (it will not overwrite your data, settings or databases), and run Alike off of the USB drive.

Consult this Citrix article for information on how to map a USB drive with a BAT file within the VM:
http://support.citrix.com/article/CTX118198