Conducive to the air circulation in the chassis. SCSI, the full name of which is small computer system interface, has experienced many generations of development. From the early SCSI-II to the present Ultra320 SCSI and Fibre Channel, there are also many connector types. SCSI hard disk is widely used in workstation-class personal computers and servers, because its rotation speed can reach 15000 rpm, and it takes up less CPU computing resources during data transmission, but its unit price is also more expensive than ata and SATA hard disks with the same capacity. SAS (Serial Attached SCSI) is a new generation of SCSI technology. Like SATA hard disk, sequential technology can achieve higher transmission speed, which can reach 3 GB/s ... In addition, the internal space of the system is improved by narrowing the connecting cable. In addition, because SAS hard disk and SATA hard disk can share the same backplane, in the same SAS storage system, some expensive SCSI hard disks can be replaced by SATA hard disks, saving the overall storage cost. The 5.25-inch and 3.5-inch desktop hard disks with power interface adopt D-type 4-pin power interface, which was designed and patented by Molex. The 2.5-inch notebook hard disk can get power directly from the data port without additional power interface. After the external portable hard disk box is plugged in, the power supply is provided by the USB interface outside the computer, and the power supply of a single USB port is 4.5V 500mA, so mobile hard disk box usually needs to connect two USB ports to use it, otherwise it needs an external power supply. The size and use of hard disk can be divided into: 0.85 inch, which is mostly used for portable devices such as mobile phones. 1 inch (MicroDrive), mostly used in digital cameras (CF type II interface). 1.8 inch, mostly used for notebook computers and external hard disk boxes. 2.5 inches, mostly used for notebook computers and external hard disk boxes. 3.5 inches, mostly used for desktop computers and external hard disk boxes. 5.25 inches, mostly used in early personal computers. There is no manufacturer to produce it yet. In addition to the interface and size, the main parameters of hard disk also include the following parameters: capacity. At present, the hard disk capacity is 36GB, 40GB, 73GB, 80GB, 120GB, 150GB, 160GB, 200GB, 250GB, 300GB, 320GB, 400GB, etc. Rotational speed The revolutions per minute of the hard disk, in rpm (revolutions per minute), mainly include 4200rpm, 5400rpm, 7200rpm, 10000rpm, 15000rpm and other specifications. There are mainly 2MB, 8MB, 16MB and 32MB caches. The unit of average seek time is ms (millisecond), and there are 5.2ms, 8.5ms, 8.9ms, 12ms and other specifications. 1956 IBM's IBM 350 RAMAC is the prototype of modern hard disk, which is equivalent to the size of two refrigerators, but the storage capacity is only 5MB. 1973, IBM 3340 came out, and he got the nickname "Winchester". This nickname came from his two 30MB storage units, which was the caliber and charge of the famous Winchester rifle at that time. At this point, the basic structure of the hard disk has been established. 1980, the company founded by two former IBM employees developed a 5.25-inch 5MB hard disk, which was the first product for desktop computers. The company was Seagate. At the end of 1980s, IBM introduced MR (Mago Resilient Reliability) technology, which greatly improved the sensitivity of the magnetic head, and the storage density of the magnetic disk was dozens of times higher than the previous 20Mbpsi (bits per square inch). This technology has laid the foundation for the huge increase of hard disk capacity. 199 1 year, IBM introduced the first 3.5-inch 1970+ 199 1 year with this technology, and the storage density of hard disk increased by 25%~30% every year. From 199 1 to 60% ~ 80%; Up to now, the speed has increased to 100% or even 200%. The amazing speed increase since 1997 is due to IBM's GMR technology, which further improves the sensitivity of the magnetic head and the storage density 1995. In order to cooperate with Intel's LX chipset, Quantum and Intel jointly issued the UDMA 33 interface-Eide standard, which increased the original interface data transmission rate from 16.6MB/s to 33 MB/s. In the same year, Seagate developed a fluid dynamic bearing (FDB) motor. The so-called FDB refers to the introduction of gyroscope technology in the production of hard disks, and the replacement of metal bearings with oil film with a thickness equivalent to one tenth of the diameter of hair, which reduces the noise and calorific value of hard disks 1996. Seagate acquired Conner peripheral in February) 1998, and UDMA 66 specification came out in June 2000. Maituo acquired quantum in June 5438 +2003 10, and Hitachi announced that it had completed the acquisition of IBM's hard disk division of $2.05 billion and established Hitachi Global Storage Technology Company.
Hitachi GST) In 2005, both Hitachi Environmental Storage and Seagate announced that they would start to adopt a large number of vertical recording technologies, that is, to change the magnetic field direction parallel to the disk to vertical (90 degrees) and make full use of storage space.
Seagate, a hard disk manufacturer, announced the acquisition of Maituo. In June 2007, Hitachi Global Storage Technology announced the release of the world's first 1TB hard disk, which was more than one year later than the original time. The hard disk costs $399, and you can buy 27.5MB of hard disk space. On June 5438+065438+ 10, 2007, a Trojan horse (virus) was found embedded in the preformatted hard disk of Maituo. Win32.AutoRun.ah) will steal the account and password of online games.
Reference: zh. ***