Hardware Reference
In-Depth Information
commodate alignment for all these types of storage devices, Windows Vista and later are
designed to start partitions on 2,048-sector (1MiB) boundaries, which are an even mul-
tiple of the larger sectors or storage units used by virtually any storage device. Figure 9.6
shows how the 4K NTFS clusters, 512-byte logical (emulated) sectors, and 4K physical
sectors would line up if the drive were partitioned under Windows 7/Vista and later.
Figure 9.6 Default 4K sector drive partition alignment on Windows 7, Vista, XP.
As you can see, Windows Vista and later versions automatically start the first partition at
sector LBA 2048, which results in a perfect alignment between the 4K NTFS clusters and
the 4K physical sectors. In this case, NTFS cluster 0 would perfectly align with physical
sector 256, and so on. Each time one cluster is written, the drive will do a normal write of
the matching physical sector, instead of a multiple sector read-modify-write operation as
would be the case with a misaligned partition.
Operating systems have used 4K cluster-based file systems (such as NTFS) for many
years now. These OSs will naturally work with 4K sector drives, as long as the start of
each partition is properly aligned. Table 9.7 shows which OSs automatically create parti-
tions properly aligned for 4K sector drives (including SSDs).
Table 9.7 Typical 4K-Byte Sector Format
Although these OSs automatically create 4K aligned partitions, you can manually create
aligned partitions for OSs that don't automatically create them, such as Windows XP.
There'saneasywaytodothisis;beforeyouinstallsuchanOS,useanOSthatdoescreate
 
 
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