What is Partition Alignment?
To understand what partition alignment is we should first see how disk clusters and sectors are arranged on a hard drive. Here you can see a simplified scheme of partitioning.
The partition consists of some logical units called clusters, and in this scheme one cluster is shown to corresponds to two sectors. The partition and the clusters are also aligned with the sectors and when this happens the partition is said to be aligned.
This is however over simplified. An actual modern hard disk drive has an internal sector size of 4KB but appear as 512 bytes to the operating system or software. To achieve this another level of abstraction is added as shown below. This emulation is needed for old-software compatibility.
What causes misaligned partition?
Misaligned partition is a problem plaguing old operating systems such as DOS and Windows earlier than Vista. Earlier operating systems reserved 63 (hidden) sectors at the beginning of the first partition of a disk. The master boot record (MBR) resides within these hidden sectors. This causes the the partitions to shift relative to the sectors as shown below.
As a result all logical clusters are now linked with two physical sectors, and all read-write operations has to be done twice. This degrades system performance as a hard disk has to make two operations with two sectors for every data read or written data instead of one as if the partition was properly aligned.
Misaligned partitions can occur on newer SSD (solid state drives) too, and affect performance on RAID configurations.
How Paragon Alignment Tool can help?
Paragon Alignment Tool moves the partition by an amount such that the clusters are once more aligned to the sectors.
If you are using Windows XP or earlier, Paragon Alignment Tool can dramatically improve your system’s performance and reduce hard drive usage.
Paragon Alignment Tool is currently available for free until June 30, 2010.