A hard power off is a good test
As a tester I always thought a power off was a good test.
A fast shutdown is not the same, it has time to write data out to disks etc.
A customer found a problem when there was an emergency power off.
As part of 2 phase commit you have to write to one disk, then write to the second disk in the right order.
We found the first write was a write to the disk buffers - it was not actually written to the spinning disk (there was a 10 millisecond window)
At recover time the data from the first disk was not there, but it was from the second disk, and the system would not restart.
Biting the hand that feeds IT
