ST31000528AS_7200.12_1 ST31000528AS_7200.12_2
It is not uncommon for us to get crashed 7200.12 hard drives from older iMac computers.  But, in the case of these two ST31000528AS 7200.12 drives, they came from a system where they were setup as a RAID 1 mirror.  The whole point of a RAID 1 mirror is if one drive fails, the other continues to work, giving the user time to replace the failed drive without losing their data.

Unfortunately, as is in this case, there are times when the first drive failure goes undetected and is only noticed after the data becomes inaccessible when the second drive fails too.

If you have data stored on a server with the drives setup in a RAID, be sure to have a solid backup of your data off the server and have someone frequently checking the server to make sure that all disk drives are working as they should.