A disk array controller is a device which manage the physical disk drives and presents them to the computer as logical units. It almost always implements hardware RAID. RAID (Redundant Array of Independent Drives) is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance, reliability, and/or larger data volume sizes. A disk array controller also provides additional disk cache.
Two key factors determine the speed of traditional, spinning hard disks. The first is the rotational velocity of the physical disk itself. This can currently be 4200, 5400, 7200, 10000 or 15000 rpm (revolutions per minute). The faster the disk spins, the quicker data can be read from or written to it, hence the faster the disk the better (although faster disks consume more power, make more noise, and generate more heat). Most desktop hard disks run at either 5400 or 7200 rpm, whilst most laptop hard disks run at 4200 or 5400. However, upgrading to a 10000 or 15000 rpm disk -- such as a Velociraptor from Western Digital -- can prove one of the most cost-effective upgrades for increasing the performance and responsiveness of a desktop computer.
When the first microcomputers were introduced in the late 1970s, and in particular when the IBM PC was launched (in 1981 in the USA and 1983 in the UK), the computer industry was dominated by hardware. This was because most of the money spent on a computer system went on hardware, with a direct trade-off existing between processing power and overall system cost. The exact hardware specification was usually also critical. Today, however, neither of these points remains the case.
In contrast, battlefield-rugged servers bring higher mean time between failures (MTBF) and can operate longer in environments that experience extreme heat, moisture, shock, and vibration, while remaining competitive with commercial server costs. A modular design for these purpose-built servers enables anything in the system to be swapped out on the battlefield, underway on board the ship, or in the air on a reconnaissance mission. This is particularly important in a submarine, for example, where carrying a few replacement modules is far more practical than hauling around a large quantity of spare servers.
The central processing unit contains many toxic materials. It contains lead and chromium in the metal plates. Resistors, semi-conductors, infrared detectors, stabilizers, cables, and wires contain cadmium. The circuit boards in a computer contain mercury, and chromium. When these types of materials, and chemicals are disposed improperly will become hazardous for the environment.
Random Access Memory, or RAM, is hardware found in the memory slots of the motherboard. The role of RAM is to temporarily store on-the-fly information created by programs and to do so in a way that makes this data immediately accessible. The tasks that require random memory could be; rendering images for graphic design, edited video or photographs, multi-tasking with multiple apps open (for example, running a game on one screen and chatting via Discord on the other).