I know IT "specialists" here and american public at large are mathematically challenged.
But 7 out of 7 hard drive failure probability is about 1 in 10^14.
that means you would have to wait 100 trillions years (on average) for that to happen.
I assumed 1% per year failure rate for HD and 1 year period within which they "failed"
The problem is "out of 7". There are a lot more than 7 drives.
No...The odds of it being the exact 7 that needed to be found are closer to the the number for Barbos. The chances that 7 drives in all of IRS being down would be higher. What are the chances that your numbers will win powerball is much lower than 7 numbers being drawn.
What makes you think there weren't more drives that were intact? An intact drive isn't newsworthy and wouldn't be reported other than possibly as a total.