On seperate desktop pc's using XP and 80GB optical internal hard drives of various brands wife & I have had nine HD failures in six years (we are octogenarians with home use only). So they fail, not IF but WHEN. Of course using Mirror RAID has doubled the HD in use but at least we have never had the ultimate catastrophe.
The Promise RAID Controller has given me much grief. Backing-up now done to a single migratable 5OOGB external HD, amply big enough --- but it is still optical.....
Not likely that the external AND an internal would fail at the same time I agree. But sod's law always applies and bread always falls buttered-side to carpet
I am considering a different arrangement & invite comments. I won't throw away my big external HD now I have it but I will add a desktop USB2 hub and a solid-state 64GB flashdrive (aka memory stick) of a known make say Verbatim. I will back up to that.
Just how reliable are these solid-state devices? Rock-solid never fail?
I won't need to run CHKDSK, Defrag nor AV scan with it cos already doing that regularly with the internal optical HD. It will be I hope fast enough on USB2.
Costs? Approx £1 per extra GB once you are on the ladder so £35 for 32GB & £90 for 64GB & £160 for £128GB so my choice of 64GB will be £90 (can be had generic for £50 though) --- 7-port triangular USB2 hub £25, 10-port chunky £30, simple 4-port £10. If I choose carefully won't need £9 USB2 cable to insert flashdrive as hopefully slim enough for direct insertion? Warning, make sure all suit 32bit as reviews indicate possible probz with 64bit which is not me anyway
I propose issuing my own commands to backup, not say a Genie auto but £30 spent in that direction does have its attractions which include rescue disc/flashdrive.
Obscurity is a comfortable cloak