Kernel Log: Linux and hard disks with 4-KByte sectors

“In future, fdisk will arrange partitions in such a way that the
new hard disks with 4-KByte sectors can achieve optimum performance
– although, for now, users will still need to select fdisk’s
appropriate mode of operation manually. The developers of Realtime
Linux have released new kernel versions, and the completion of
2.6.32.9 and 2.6.33 is also approaching.

“Red Hat developer Karel Zak has released version 2.17.1 of the
util-linux-ng tool collection used in many Linux distributions. It
includes the “fdisk” command line program which, in its
sector-based mode of operation, activated via the “-u” option, will
from now on try to align partitions along megabyte boundaries in
the same way as Windows 7 and Vista have done for some time. While
this sounds like a minor change, it is essential for the gradually
emerging large hard disks that work with 4-KByte sectors internally
while, for compatibility reasons, externally pretending to use
512-Byte sectors like any other desktop hard disk released in the
past 20 years.

“Linux file systems prefer to read and write in 4-KByte blocks,
but older versions of fdisk arrange the first partition in such a
way that it begins with the (512-Byte) sector 63 by default –
which is right in the middle of a physical (4-KByte) sector.
Writing 4 KBytes of data to the beginning of the partition
consequently requires the hard disk to read two physical sectors of
4 KBytes, distribute the 4 KBytes of data across these two physical
sectors, wait for the disks to do an extra round and then write the
two sectors back to disk.”

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