I use 2 1.5 TB portable WD drives which I swap over intermittently to back up all my data.
I take one drive and leave it at work and swap them over regularly so no drive back up is ever too old.
I've found a free programme called SyncToy (a MS product) to be perfect to keep it all under control. And it's dead simple.
Any system that works and the user understands is ideal. Just make sure that you fully understand what is happening and you know how to recover
. Perform a recovery to be sure the product works as it says
. (Many products don't work like they should!) Many folks never test their recovery and find out too late it's flawed! Ouch!
Something to remember about Sync type scenarios. Depending on the sync schedule (frequency), the sync copy will eventually end up inheriting the changes of the master. That's fine if intended, not so fine if unintended. In wayno's
case, he has another disconnected copy offsite that might save him if the unintended changes are caught before the swap. Just understand that a sync copy isn't quite the same as a backup, it's a delayed redundant copy. Sort of a like a slow mirror. So in the case of accidental changes, deletions or viruses, it's not much good because all the mistakes are copied too.
Don't get me wrong, a sync is great if it's used correctly and is fully understood. I do manual syncs only after I finish some work I am happy to have copies of. (And I know there is another true backup copy to go back to later if necessary.)