That's right. We've got 4 bog standard 750G WD Caviar Blues in a software RAID array in that machine, all powered up for 11+ years, none of which appear to have caught any errors during that time. Pretty amazing.
The OS has been updated and the box rebooted for kernel updates a number of times over the years.
Yes I suspected as much. So really this is bragging about continuous power for 11 years. Which is impressive.
I never saw anyone measure uptime in that way before. But it make a lot more sense than measuring the OS uptime.
[Edit] - Slightly pedantically, it's the number of hours one of the disks has been powered up