4K Sector HDD FAQ Dell Enterprise Disk Engineering January 3, 2014
Terminology Sector – An atomic unit of data transfer size from/to Hard Disk Drive Logical Block Address (LBA) – An atomic unit of 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 512-byte Native, 512n Advanced Format, AF, 512e, 512E, 512-byte Emulation Reported Logical Sector Size Reported Physical Sector Size Windows Version with Support 512 bytes 512 bytes All Windows versions 512 bytes 4096 bytes • • • • Advanced Format native, AFn, 4K Native, 4Kn* 4096 bytes 4096 bytes Windows Server 2012 Windows Server 2008 R2 w/ MS KB 982018 Windows Server 2008 R2 SP1 Windows Server 2008 w/ MS KB 2553708 Windows Server 2012 (4k data disks are supported and as boot di
misaligned data, the 512e HDD must perform READ-MODIFY-WRITE functions to complete the write operations. Therefore, 512e HDD suffers significant performance loss (50%) in the random writes, misaligned data operations. In addition, a sudden power loss during READ-MODIFY-WRITE operation could corrupt the physical sector causing data loss/corruption on adjacent logical sectors within the affected physical sector.
6. When is 4k sector HDD happening? 4k sector HDD started on Notebook HDD in Q3 ‘2010, on Desktop HDD in 2011, selective Cloud Enterprise HDD in 2013 and will be on mainstream Enterprise HDD in 2014. Dell is leading this transition by adopting these drives in PowerEdge , Power Vault, EqualLogic and Compellent systems. Notebooks: The transition started with 2.5” notebook drives, starting with the largest capacity (750GB) new drive families in late 2010. The mainstream 2.
9. Is there data integrity risk during sudden power off? If volatile write cache is disabled: • • 512n and 4kn HDD, there is no data loss during sudden power off. Enterprise 512e HDD with NVC and/or MBC/MC feature (see section 5) also does not have data integrity risk. • For 512e without NVC or MBC/MC (Client grade HDD), 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.
