Hard Disk Drive Services
A common reason for computer repair is the failure of a hard drive. Perhaps the reader who is a veteran user of Microsoft-powered PC's has experienced at least one heart-stopping 'blue screen of death' over the course of their computing career.
A HDD: Hard Disk Drive; often truncated as "Hard Drive", "HDD" or just as "HD" is a data storage device which was first introduced on September 13, 1953 and its commercial usage began 1956. Inside its air-sealed casing are one or more platters, its read/write head, magnets and the read/write actuator among other things. The internal hard disk is most commonly located in the drive bay and it connects to the motherboard via SCSI, ATA or SATA cables, and of course another cable line to connect to the power supply unit (PSU).
History, Development and Capacity
As mentioned before, the HDD was first introduced in 1953 when IBM recognized its application considering high capacity, rapid random access at a seemingly low cost. A lot of different technologies were considered back then in IBM, including stuff like wire matrices, rod and drum arrays etc. The engineers with the IBM's San Jose California facility finally invented the hard disk drive.
IBM started shipping these units commercially in 1956, specifically with the IBM 305 RAMAC system, which included the IBM Model 350 disk storage device. Fourteen years later on March 24, 1970, a fundamental patent was issued, arising from the IBM RAMAC program.
Later on, the more it was developed and researched, each generation of the hard disk drives became smaller, faster and more reliable. For example, the very first hard drives were only usable within the protected environment of the data center. Later versions reached factories, offices, homes and eventually pervasiveness.
The dimensions (diameter) of these drives was initially about 8 to 14 inches (200 or 360 mm) and these were normally installed in standalone boxes or very large equipment enclosures. Not only that, the initial hard disk drives used very large motors in order to spin the large disks, and that required high-current AC power. Needless to say, the hard drives were not used with microcomputers in that time, not until 1980 when Seagate Technology announced the ST-506, first hard drive of its size, of only 5.25 inches or 133 mm.
As the technology progressed, so have the speed, reliability and availability of hard drives. Capacity alone has been enhanced so much that for many people today, it is unbelievable that the first hard drives had a storage capacity of only 5 megabytes. The hard disk drives today of course, offer something way different, as of late 2014, the largest-capacity disk drives were able to contain up to 8 terabytes of data.
Reading and Storing Data on the HDD
Data being sent to and from the hard disk drive is interpreted by something called the disk controller, the disk controller is found on the back side of the hard drive and its function is to instruct the drive on exactly what to write and/or how to move the pieces around inside of the drive itself. For example, when the system needs to write or read information it will first examine something named a File Allocation Table (FAT) in order to determine location of the files and available fields. After that's done, the actuator will move its read/write arm and align the read/write head, this is done in order for the head to be able to access all of the information, since the files are most commonly scattered all throughout the platter.
Every piece of data and information found on a common hard disk drive is stored magnetically. The read/write head aligns the magnetic polarities of the mentioned magnets in the hard drive, and writes 0's and 1's which the computer can read later in binary language, in order to be able to write to the platter.
Many users today prefer external hard drives in order to expand storage capabilities and access needed information whenever it is needed, without the drive itself needing to reside inside the computer housing. The external hard drive is often enclosed within a case of some kind for protection and easy connection - which is established trough either eSATA or a simple USB cable. One can see the advantages of an external HDD, considering it's very useful for storing important information and files, while it's completely movable and can easily follow you in your bag wherever you may need to go.
Enter Solid State Drives (SSDs)
A Solid State Drive or a SSD pretty much shares the same functions and usages as the hard disk drive, meaning it does the same job of being a storage device, only the new SSDs offer all of this at amazingly higher speeds than the HDD. Instead of magnetic coating on the platters within these drives, the SSD stored the data on interconnected flash memory chips, and these chips are able to retain the data even when the system is off (no power present).
Today, these kind of drives are commonly permanently installed within the motherboard, for example on some laptops and ultrabooks or high end work stations. As said, they differ from HDDs and USB thumb drives both in the type, and the speed of the memory.
Of course, with great power comes great..., well not responsibility as much as cash. That's right, the solid state drives are consequently more expensive than either the hard disk drives or flash memory USB thumb drives.