4K Sector HDD FAQ Dell Engineering May 2015 Authors: Frank Widjaja and Chetan Kumar, Dell Enterprise Disk Engineering 1 4K Sector HDD FAQ
Revisions Date Description Jan 2014 Initial release May 2015 Updated the template FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND. © 2015 Dell Inc. All rights reserved. Reproduction of this material in any manner whatsoever without the express written permission of Dell Inc. is strictly forbidden. For more information, contact Dell.
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Contents Revisions ............................................................................................................................................................................................. 2 Terminology....................................................................................................................................................................................... 5 Frequently Asked Questions .............................................................................
Terminology Sector – An atomic unit of data transfer size from/to a hard Disk Drive LBA (Logical Block Address) – An atomic unit of hard disk drive (HDD) sector address (location). Physical Sector – Sector size at the HDD media level, normally is 512 bytes Physical LBA – LBA layout on HDD media level, each LBA has the Physical Sector size Logical Sector – Sector size defined at the host–to-disk drive interface. Normally the same size as Physical Sector unless the HDD is emulating.
Common Names Reported Logical Sector Size 512 bytes 512 bytes Reported Physical Sector Size 512 bytes 4096 bytes Windows Version with Support 512-byte Native, 512n All Windows versions Advanced Format, AF, Windows Server 2012 512e, 512E, 512-byte Windows Server 2008 Emulation R2 w/ MS KB 982018 Windows Server 2008 R2 SP1 Windows Server 2008 w/ MS KB 2553708 Advanced Format 4096 bytes 4096 bytes Windows Server 2012 native, AFn, 4K Native, (4K data disks are 4Kn* supported and as boot disks in UEFI mode) W
4. What is Advanced Format? Advanced Format is the term for 4K sector HDD or 512e HDD implementation. 5. How can performance issues and data risk be mitigated? As stated before, the main reason for 512e performance issues is misalignment during writes. Newer operating systems and applications are 512e-disk aware and minimize the incident of READMODIFY-WRITE. Writing data on an aligned 4K boundary and in multiple of 4K bytes eliminates the READMODIFY-WRITE operation.
Notebooks: The transition started with 2.5” notebook drives, starting with the largest capacity (750 GB) new drive families in late 2010. The mainstream 2.5” capacities (250GB-500GB) for notebooks transitioned to 4K sector (512e) in mid-2011. Desktops: 3.5” HDD has ~3x the capacity point of 2.5” HDD so the demand of high capacity 3.5” HDD was less than the 2.5” HDD. The transition occurred with the 4TB product introduction in 2012.
• For"512e"without"NVC"or"MBC/MC"(Client"grade"HDD"for"example),"there"is"a"risk"of"data"integrity" during"sudden"power"loss. If volatile write cache is enabled, then sudden power loss will result in data cache loss regardless of the HDD format types.
