Dell PowerEdge C4130 - Manual (Page 6)

6 512e and 4Kn Disk Formats
3 The long-term benefit of 4K sectors
Since all hard drive manufacturers have agreed to transition to the Advanced Format sector, the industry
must adapt to and embrace this change to minimize potential negative side effects. Short-term benefits to
end users will not be dramatic in terms of immediate capacity increases. However, the migration to 4K-
sized sectors will most definitely provide quicker paths to higher areal densities and hard drive capacities,
as well as more robust error correction. Reducing the amount of space used for error correction code
improves format efficiency.
The legacy 512-byte sector has non-data-related overhead for the Gap, Sync and Address Mark sections
for every 512-byte. The new Advanced Format standard of a 4K-byte sector essentially combines eight
legacy 512-byte sectors into a single 4K-byte sector. The Advanced Format standard uses the same
number of bytes for Gap, Sync and Address Mark, but increases the ECC fields. This yields a format
efficiency of 97 percent, almost a 10 percent improvement. Together, the benefits of improved format
efficiency and more robust error correction make the transition to 4K sectors well worth the effort.
Properly managing this transition to capture the long-term benefits with minimal side effects is a key focus
for the hard drive industry.
4 Understanding the impacts of the 4K transition
As noted earlier, there are many aspects of modern computing systems that continue to assume that
sectors are always 512 bytes. To transition the entire industry over to the new 4K standard and expect all of
these legacy assumptions to suddenly change is simply not realistic. Over time, the implementation of
native 4K sectors, where both host and hard drive exchange data in 4K blocks, will take place. Until then,
Dell and our competition will also implement the 4K sector transition in conjunction with a technique
called 512-byte sector emulation.
The most critical aspect of a smooth and successful transition to 4K sectors used in Advanced Format is
performance. Whether you are a system builder, OEM, integrator, IT professional or end user building or
configuring a computer, to ensure you have the performance you need for a successful transition, use the
operating system to align partitions on a 4Kn drive boundary.
For operating system versions that are not 4K-sector aware, use third-party software or utilities to create
hard drive partitions. To ensure the software or utilities you are using are 4K-sector aware, check with your
Dell team.
4.1 512-byte sector emulation
The introduction of 4K-sized sectors depends heavily on 512-byte sector emulation. This term refers to
the process of translating from the 4K physical sectors used in Advanced Format to the legacy 512-byte
sectors expected by host computing systems.
The 512-byte emulation is acceptable in that it does not force complex changes in legacy computing
systems. However, it carries the potential for negative performance consequences, particularly when
writing data that does not neatly correspond to eight translated legacy sectors, as evident by the 512-byte
emulation writing process.