I’ve had a ReadyNAS Duo probably for about a year, now, and quite honestly can’t fault the little black box. Managing computer systems during the day, I have little interest in doing the same at home. The Duo provides home media sharing (DLNA and iTunes), a shared printer, Time Machine backup service, network storage for MythTV, UPS integration, and pretty good configuration and automation.
However as we know RAID is not a backup solution, so I still have to get the data onto some other media and preferably out of the house. For this we have a Western Digital Elements external USB hard drive, to which the Duo copies data when connected.
For Time Machine backups it’s not obvious how to get copies of the sparsebundles. I found that they’re stored in the Duo’s c: volume, in a folder called .timemachine. This can either be backed up with the whole of c: in one job, or separately if referred to by itself.