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Laptop hard disk drives are smaller variants of the larger desktop counterparts and usually emphasize power use a lot more than raw capacity of groundbreaking performance. There are fair a number of major industry stalwarts competing within the cutthroat laptop hard disk business: Fujitsu, Hitachi, Samsung, Seagate, and Western Digital.
Past generations of laptop hard disk drives relied on parallel ATA interfaces which not just limited transfer bandwidth, but were not as electrically efficient because the power sipping SATA and SATA 3.0 Gpbs standards that saturate the current market. The interface is really a key performance factor of laptop hard disk drives as it is a measure from the maximum amount of data that can be transferred to and from the drive. While the interface standards for laptop hard disk drives has kept well ahead of their sustained performance potential, it's not uncommon for the interface to be a limiting factor for transfer performance in quick bursts.
Another performance characteristic, often considered to be the primary factor influencing overall read/write speed as well as access time may be the rotation velocity. Laptop hard drives have power and thermal constraints to limit their performance to spindles with speeds of 7200 rotations each minute (RPM) or less. The faster confirmed disk can rotate its magnetic platter(s), the faster it can write information as well as find and browse stored data. Even at 7200 rpm, the performance of laptop hard disk drives doesn't measure up to that of similar capacity desktop units.
One of the major reasons for this is actually the number of platters is restricted through the physical height of the drive. Magnetic platters that store data in almost any hard disk require a certain amount of space together in order for a read/write visit move across them and create, change, or access information. Laptop hard drives are physically smaller, and thus the quantity of platters is limited, but same with the performance per platter. Take any two spinning circles of various sizes and something will note that when rotating the same quantity of times within the same period, the outer edges of the larger circle will travel a larger total distance. In the world of laptop hard disk drives which means that the length a read/write covers at 7200 rpm is quantifiably under the distance it might cover when the platter were physically larger.
The platters themselves also play a factor. The more densely packed the data, known as the aural density, the faster it can generally be read from and also the quicker it can be written. This isn't always true, as sometimes the technology for that read/write heads lags behinds and an increase in aural density results in slower seek times.
The ultimate performance related factor for laptop hard drives is the cache. The cache is a small pool of volatile memory much like system RAM that acts as a buffer for writes and frequently stores recently and/or frequently accessed information. The buffer is the primary reason interface standards can limit bursting performance regardless of the insufficient sustainable performance approaching theoretical limits of the interface specification.