Disk drive manufacturers are transitioning to the production of Advanced Format disk drives, which have 4 KB physical sector size instead of the traditional 512 bytes. While larger sectors will ultimately improve performance, many applications are not written to take advantage of the change, so a transitional technology called “512-byte emulation” is used to support the 512 byte logical addressing. These disks are known as “512e” disks, for short.
Advanced Format drives will ultimately be the future standard, however some applications may have issues with the transitional 512e drives, especially if you are imaging a machine to new hardware and the OS and applications aren’t expecting a difference in physical and logical sector sizes.
Microsoft has a hotfix available for Windows 7 and Windows Server 2008 R2 than can address several potential issues introduced with this type of disk. Check out KB 982018 for additional details and several known issues. I’d be particularly aware if you are doing any P2P migrations of servers that support Active Directory, DHCP or act as a CA, as the ESENT engine is sensitive to the reporting of sector size, as detailed in issue #1 of the knowledge base article.