11 512e and 4Kn Disk Formats
5.5 Dealing with unaligned conditions
Using a 4K-aware version of an operating system to create hard drive partitions is a simple, straightforward
method for avoiding unaligned conditions. Some third-party firms offer utilities that examine existing hard
drive partitions and realign them as needed. This alternative takes additional time and adds steps to the
system building or upgrading process. Ultimately, Dell will develop more sophisticated methods and
design systems to manage unaligned conditions to mitigate negative performance impacts.
5.6 512e/4Kn application support
Not all applications are 4K physical sector aware. Table 6 summarizes the 4K application support. When an
application is 512e/4Kn aware, the I/Os will be compliant to the file system partition, and the drives will run
at expected performance level.
Table 6 Application support
*It is more of supportability issue that Microsoft has not fully tested/validated Exchange with 4Kn drives. Since
Exchange does its own replication, it is very sensitive to the disk types, in particular to disk sector sizes and does not
recommend having different disk types as part of the same Database availability group. There are issues where the
replication can fail; for example, you have a 512n disk hosting one DB copy and a 512e disk hosting another DB copy.
See the following article for more details:
http://blogs.technet.com/b/exchange/archive/2013/04/24/exchange-2010-
database-availability-groups-and-disk-sector-sizes.aspx
**VMware may support 4Kn drives in 2014. VMware currently supports 512e formats.
6 Drive labels
The AF Logo Program was created by IDEMA and the Advanced Format Marketing Work Group to easily
identify hard disk drives that employ long sector, AF technologies. While usage of the logo is optional, AF
logos may be seen populating hard drive product labels, product pages, and various literatures to indicate
the usage of AF technologies versus legacy sector size architectures that were used in earlier drives.
The AF emulation logo has one rounded corner and is used on any client or enterprise hard drive that is
equipped with industry-standard emulation techniques. AF 512e is the current standard by which
downward compatibility with legacy sector formats is achieved.
The AF native logo identifies the presence of AF native technologies, where data using long data sector
format standards is both recorded on the drive and passed to the host in the AF format. Unlike AF
emulation, there is no modification of the sector size by which the data is processed or communicated to
the host.
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