Hardware Reference
In-Depth Information
reading and writing. In the outer zone, the data transfer rate is nearly 118MBps, where-
as in the inner zone it is only 56MBps. The average transfer rate for this drive is around
80MBps. This is one reason you might notice huge discrepancies in the results produced
by disk drive benchmark programs. A test that reads or writes files on the outer tracks of
the disk naturally yields far better results than one conducted on the inner tracks. It might
appear as though your drive is running more slowly when the problem is actually that the
test results you are comparing stem from disk activity on different zones.
Another thing to note is that this drive conforms to the SATA 3Gbps specification and is
capableofaninterfacetransferspeedof300MBps.Asyoucansee,thatisentirelytheoret-
ical because the true media transfer speed of this drive varies between about 56MBps and
118MBps, averaging about 80MBps overall. The interface transfer rate is just that: what
the interface is capable of. It has little bearing on the actual capabilities of the drive.
The use of zoned recording enables drive manufacturers to increase the capacity of their
hard drives by 20%-50% or more compared to a fixed-sector-per-track arrangement. All
modern drives use zoned recording.
Partitioning
Creating apartition onanHDDenables ittosupportseparate file systems, each initsown
partition.
Each file system can then use its own method to allocate file space in logical units called
clusters
or
allocation units
.EveryHDDmusthaveatleastonepartitiononitandcanhave
up to four partitions, each of which can support the same or different type file systems.
Three common file systems are used by PC OSs today:
•
FAT (file allocation table)
—The standard file system supported by DOS and Win-
dows 9x/Me. FAT is also the default file system used by Windows 2000 and later
on flash or other removable drives. FAT partitions support filenames of 11 characters
maximum (8 characters + a 3-character extension) under DOS, and 255 characters un-
derWindows9x(orlater). ThestandardFATfilesystem uses12-or16-bitnumbersto
identify clusters, resulting in a maximum volume size of 2GB.
•
FAT32 (FAT, 32-bit)
—An optional file system supported by Windows 95 OSR2
(OEM Service Release 2) and later.
FAT32uses32-bitnumberstoidentifyclusters,resultinginamaximumsinglevolume
size of 2TB, or 2,048GB.
•
NTFS
—The native file system for Windows NT and later that supports filenames
up to 256 characters long and partitions up to (a theoretical) 16 exabytes. NTFS also
