Re: on the theory that some data might be on that but not yet in the backup
I had a RAID6 fail with three drives dying in quick succession - I suspect the first chucked up some nasty vibrations in its death throes that took out the two next to it...
And it was on Christmas Eve...
Still, the on-site backups worked well enough to get me through to the New Year on a reduced array (and a couple of hot spare machines) until I could get hands on to sort it out...