Thanks. I missed that part on the data sheet.
Do you (or anyone) have a definitive answer to whether Windows 7 system image backups work on AF drives? The thread I linked to in my original post suggests a problem, but the MS KB article says
If you are using a logical sector drive of a size other than 512 bytes, Windows system image backup and restore operations may fail, and you receive the following error message:
I guess the more pertinent question is whether the WD Red drivers are 512e AF drives (that is, report 512 byte logical sectors) or whether they are “4096 native” AF drives. I assume that they are “Advanced Format 512e” … but it would be nice to know for sure.