Using 4k sector and advanced format drives in Windows. HotFix and support info for Windows Server 2008 R2 and Windows 7

If you work with storage, you probably already heard about the “4K Sector Drives”, “Advanced Format Drives” and “512e drives”. These new “4K sector drives” abandon the traditional use of 512 bytes per sector in favor of a new structure that uses 4096 bytes. The migration to the new formats is eased by the use of 4K drives that simulate the old format, known as “512 Emulation Drives” or “512e Drives” or Advanced Format Drives”.
Native 4K sector drives are currently not supported with Windows. However, 512e drives (or Advanced Format Drives) are supported with recent versions of Windows, provided that you follow the guidance in the following support article: There are specific requirements to be met and specific details for different Microsoft applications like Hyper-V, SQL Server and Exchange Server.
For Windows 7 and Windows Server 2008 R2, the KB article above mentions the requirement to install a specific hotfix described at Please note that most of this fix is part of Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 SP1, except for updates to the FSUTIL tool.

For you developers, head on over to MSDN to read on the nitty gritty details of this storage transition, and how it may impact your applications. Details are published at

If you’re interested in these new 4K sector drives, you might also want to look at these other links:

Note: The updated version of FSUTIL is available as a download from the support KB page and, since 4/26/2011, via Windows Update labeled as "Update for Windows 7 (KB982018)".


After I posted this blog, MikeH asked on FileCab: Is there any way I can figure out if the installed drive uses 4K or emulation mode?

Answer: You can recognize "Advanced Format" drives (also known as 512e or 512 emulation) by using FSUTIL FSINFO NTFSINFO <drive> and looking at the "Bytes per Sector" and "Bytes Per Physical Sector". Those drives will show 512 bytes per sector but 4096 (4K) bytes per physical sector. For more details, read the section titled "Issue 6" at