Laptop hard drives are smaller variants of the larger desktop counterparts and generally emphasize power efficiency more than raw capacity of groundbreaking performance. You will find 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 drives relied on parallel ATA interfaces which not just limited transfer bandwidth, but were not as electrically efficient as the power sipping SATA and SATA 3.0 Gpbs standards that saturate the current market. The interface is a key performance factor of all laptop hard drives as it is a stride of the maximum quantity of data that can be used in and in the drive. While the interface standards for laptop hard drives has kept well in front of their sustained performance potential, it is 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 is the rotation velocity. Laptop hard disk drives have power and thermal constraints that limit their performance to spindles with speeds of 7200 rotations per minute (RPM) or less. The faster a given disk can rotate its magnetic platter(s), the faster it can write information in addition to find and browse stored data. Even at 7200 rpm, the performance of laptop hard drives doesn't compare well to that of comparable capacity desktop units.
One of the leading causes of this is the quantity of platters is restricted by the physical height from the drive. Magnetic platters that store data in any hard disk require a certain amount of space between them in order for a read/write visit move across them and make, change, or access information. Laptop hard drives are physically smaller, and thus the amount of platters is restricted, but so is the performance per platter. Take any two spinning circles of different sizes and something will observe that when rotating exactly the same quantity of times within the same period, the outer edges from the larger circle will travel a larger total distance. In the world of laptop hard disk drives this means that the distance a read/write covers at 7200 rpm is quantifiably under the length it would cover when the platter were physically larger.
The platters themselves also play an issue. The more densely packed the data, known as the aural density, the faster it may generally be read from and the quicker it can be written. This is not always true, as sometimes the technology for the read/write heads lags behinds and an rise in aural density leads to slower seek times.
The final performance related factor for laptop hard disk drives is the cache. The cache is a small pool of volatile memory much like system RAM that provides a buffer for writes and often stores recently and/or frequently accessed information. The buffer may be the primary reason interface standards can limit bursting performance despite the insufficient sustainable performance approaching theoretical limits of the interface specification.