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Added a note about nvme (#29814)

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2019-02-06 22:29:23 +01:00
committed by Christopher McCormack
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guide/english/computer-hardware/hard-drives/index.md
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@ -8,7 +8,7 @@ Hard drives are permanent storage devices for computers. There are several types
Traditional hard disks use magnetic needles and rotating magnetized platters to store data. Due to these moving parts, hard drives are easily damaged by drops and/or shocks. The motor that rotates the platters also consumes a lot of power, and yet no other storage method is as affordable for large volumes of storage.
Hard drives come in various storage capacities, with some even storing 10TB (10 trillion bytes). Typical computers come with 256GB (256 million bytes) to 1TB of storage space. Laptops usually use Solid State Drives (SSDs) because they are faster, lighter, and contain no moving parts, making them less likely to fail due to impact. For the same amount of storage, SSDs are generally more expensive than hard drives. Recently, some SSDs have been released that interface with the motherboard through the PCI Express (PCIe) bus slot using a system called Non-Volatile Memory Express (NVMe). These SSDs have proven to be even faster at read/write times than traditional Serial Advanced Technology Attachment (SATA) SSDs.
Hard drives come in various storage capacities, with some even storing 10TB (10 trillion bytes). Typical computers come with 256GB (256 million bytes) to 1TB of storage space. Laptops usually use Solid State Drives (SSDs) because they are faster, lighter, and contain no moving parts, making them less likely to fail due to impact. For the same amount of storage, SSDs are generally more expensive than hard drives. Recently, some SSDs have been released that interface with the motherboard through the PCI Express (PCIe) bus slot using a system called Non-Volatile Memory Express (NVMe). These SSDs have proven to be even faster at read/write times than traditional Serial Advanced Technology Attachment (SATA) SSDs, because NVMe is capable of fully using the ability of SSDs to serve parallel requests.
Magnetic heads are responsible for reading and writing data, which is physically stored on a set of magnetically coated discs stacked above one another, referred to as a platter. The heads are located at the end of an armature. The interior discs of the platter have two heads on a single arm. This allows data to be accessed from both the discs, beneath and above the arm. The top and bottom discs of the platter only have one head at the end of an arm. On the opposite end of the arm is an actuator. It provides movement of the arm to travel from the center of the platter, the spindle, to the outermost regions of the platter. The amount of time it takes to place the head in the correct concentric location is referred to as the seek time. Once the head is in the correct concentric spatial location more time is spent waiting for the disc to rotate such that the sector with the requested data is beneath the head. This amount of time is referred to as latency.