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As for the backup itself seems obvious to me I should clone my primary drive. Unless there's another strategy I should consider here as well? I'm good with Time Machine just for home in case I want to roll back to an earlier version of a file and I'm not interested in manually copying files to the HD. SuperDuper! is the free one and CCC is the one you have to buy, correct?
Thanks again for all the tips.
You are correct, the best backup strategy is the one that is easy enough you actually do it. If powering down the NAS to swap drives is just that little bit too trouble to do it (and I am serious here - because I understand that sometimes it's the simple little things that we keep putting off) then you need to find something else.
I'm not saying this is the solution for you... but this is mine.
I backup my system files and and photos separately, each to a different external HDD, nightly using Smart Update with SuperDuper! (This is a cloned backup). I
also use Time Machine to backup my system files.
The TM copy is for recovering from user errors.... files I didn't mean to write over or delete.
The cloned copy is for hardware failures. One of the features of a cloned backup is that you can make it bootable (this may even be the default). If the primary HDD fails I can simply boot from the backup. There are still some things missing (caches, and some history files are missing) but nothing serious. Also applications that use a hardware signature to validate themselves will become "unlicensed". But, for 99% of the stuff you need to do - the system is entirely useable. However, it works only as fast at the interface - for this reason my system backup goes to a Firewire 800 external HDD.
The other cool thing about a bootable backup is that you can boot another computer from it. So if your whole system goes in for service, you can boot a second computer from the backup and keep working. You are limited by the hardware of the secondary computer, of course... but for email and working on documents this works fine. I used my MBP for a week while my MacPro was in the shop. Photoshop was brutal, but I could at least keep my business moving.
Why I like 3 external HDDs for my photos (with one going off-site) is simply because if I have gone too long between swap cycles, I can still rotate a HDD into place so that I have two relatively current ext HDDs - even if both of them in on-site for longer than they should be. It's still better than only having one current backup.
I don't bother with TM on my photos because I use Lightroom. It is relatively difficult to delete an original image in Lightroom, and the overhead of writing to the TM is more than I want to deal with.