Second, the hard disk term explains the rotational speed of the hard disk: the speed of the hard disk motor spindle, the speed is one of the key factors that determine the internal transmission rate of the hard disk, and its quick slowness has largely affected the speed of the hard disk, while speeding speed The quick slow is also one of the important signs that distinguish the hard disk. The spindle motor of the hard disk drives the disc at high speed to generate buoyancy to float the head over the disc. To bring the sector you want to access to the head below the head, the faster the speed, the shorter waiting time. Therefore, the speed determines the speed of the hard disk to a large extent. At present, there are usually 5400 rpm, 7200 rpm, or even 10,000 rpm on the market. In theory, the faster the speed is, the better. Because higher speeds can shorten the average search time and actual read and write time of the hard disk. However, the faster the speed, the larger the heat, which is not conducive to heat dissipation. The mainstream hard drive speed is typically 7200 rpm. As the hard disk capacity is increasing, the speed of the hard disk is also increasing. However, the improvement of the speed also brings a series of negative effects such as wear, temperature rise, and increased noise. Thus, the Fluid Dynamic Bearing Motors in the precision machinery industry is introduced into the hard disk technology. The liquid bearing motor uses a mucosa liquid oil bearing that is replaced by an oil film. This can avoid direct friction of the metal surface, minimize the noise and temperature; the oil film can effectively absorb the vibration, enabling the seismic ability; more reduced wear, improve the life. Average seek time: Refers to the time that the hard disk moves the read writing on the disk to the specified track to find the corresponding target data, which describes the ability of the hard disk to read data, and units in milliseconds. When the single disc capacity is increased, the seek action and moving distance of the magnetic head are reduced, thereby reducing the average search time and speeds up the hard disk speed. At present, the average roof of the mainstream hard drive on the market is generally 9ms or less, and the hard drive greater than 10ms is a earlier product, which is generally not worth buying. Average Latency Time: Refers to the time to continue to rotate to the magnetic head after the head moves to the data where the data is moved, and then waits for the time to continue to rotate under the magnetic head, generally between 2 ms-6ms. Average Access Time: The average time to find the specified data is usually the sum of the average roof time and the average latency. The average access time can represent the time used by the hard disk to find a certain amount of data, the better the average access time, generally between 11 ms-18ms. Note: Most of the average access hours in many hard drive advertisements are now replaced by average finding time. BURST DATA TRANSFER RATE: Refers to the highest rate of the computer read data from the hard disk internal cache area through the data bus. Also called external data transfer rates. The external transmission rate of the hard disk currently adopted UDMA / 66 technology has reached 66.6Mb / s. The maximum internal data transfer rate: refers to the maximum data transfer rate between the head to the hard disk cache, generally depending on the disk speed of the hard disk and the disk data line density (refers to the data spacer on the same track). Also called sustaind transport rates.
The internal transmission rate of the hard disk of the UDMA / 66 technology is generally 25-30Mb / s, only a few products exceeds 30Mb / s, because the internal data transfer rate is the real bottleneck of the system, so everyone should distinguish these two times when buying Concept. However, in general, when the speed of the hard disk is the same, the single-disc capacity is high; the internal transmission rate of the hard disk having a high speed is high when the single disc capacity is the same. Automatic detection analysis and reporting technology (S.M.A.R.T): The factory hard drive is now basically supports S.M.A.R.t technology. This technique can monitor the head unit of the hard disk, the disk motor drive system, the internal circuit, and the disc surface media material, etc., and when SMART monitors and analyzes the hard disk, it will be alarm to the user to avoid computer data. loss. S.m.a.r.T technology must only work on the premise of motherboard support, and S.m.a.r.T technology does not guarantee the possible hard disk failure. The magnetoresistive head technology MR (Magneto-Resistive Head): MR (Magneto-ResitiveHead) is a referred to as a magnetoresistive head. MR technology can record density, record data, increasing the hard disk capacity and increase data throughput. The current MR technology has several generations of products. Maxtor's diamond three-generation / four generations have adopted the latest MR technology. The working principle of the magnetoresistive head is based on the magnetoresistance effect. The core is a small sheet metal material, which varies with the change in the magnetic field. Although its change rate is less than 2%, but because the magnetoresistive element is connected to a very sensitive The amplifier, so that the tiny resistance change can be measured. MR technology can increase the hard disk capacity by more than 40%. GMR (GIANTMAGNETORESIVE) GMR head is the same as the MR magnetic head, and the resistance value of the special material is used to read the data on the disk with the principle of magnetic field changes, but the GMR head uses a magnetoresistive effect, better materials and multiple layers. The thin film structure is more sensitive than the MR head, the same magnetic field change can cause a larger resistance value to change, so that higher storage density can achieve a higher storage density can be achieved by 3Gbit-5Gbit / IN2 ( GM per square inch), while the GMR head can reach 10Gbit-40Gbit / IN2 or more. At present, the GMR magnetic head is already in a mature promotion period. In the next few years, it will gradually replace the MR head and become the most popular magnetic head technology. Cache: The cache is a place where the hard disk is exchanged with external bus. The process of reading data of the hard disk is to convert the magnetic signal into an electrical signal, fill the empty, fill, then empty, step by step by cached, then fill, then emptying, according to the cycle of the PCI bus, can be seen, the role of the cache is quite important. When interface technology has evolved to a relatively mature stage, the size and speed of the cache are important to directly related to the transmission speed of the hard disk. At present, there are several mainstream hard drives, including several 512KB and 2MB. Its type is generally EDO DRAM or SDRAM, which is generally mainly SDRAM. Based on the way the write mode, there are two written forms and backcrops. When reading hard disk data, the system checks the request instruction first to see if the required data is in the cache, if the response is sent out by the cache, this process is called hit. Such the system does not have to access data in the hard disk. Since the speed of SDRAM is much faster than the magnetic medium, the speed of data transmission is accelerated. The reply is that it is also looking for a cache when writing to the hard disk data. If it is found to be written by the cache, most hard drives currently use the reply hard disk, which greatly improves performance.
Continuous failure time (MTBF): Refers to the longest time of the hard disk from starting to the failure. The MTBF of the typical hard drive is at least 300,000 or 40000 hours. Partial response fully matched technology PRML (Partial Response Maximum Likelihood): The disc can store more information while effectively increase the reading and data transfer rate of the data. It is one of the advanced technologies currently applied to the hard disk data reading channel. The PRML technology is to divide the hard disk data reading circuit into two "operation line", and the first segment of the pipelines performs the signal read by the head and only selects the part "standard" signal to transfer the second segment to continue processing, the second paragraph will The received signal is compared to the PRML chip preset signal model, and then selects the smallest difference of the difference in the combination to output to complete the reading process of the data. PRML technology can reduce the error rate of the hard disk read data, so the disk data intensity can be further improved. Single track time (Single Track Seek Time): When the head is transferred from a track to another track. Super Digital Signal Processor (ULTRA DSP) Technology: Mathematical operation with Ultra DSP, with a speed of 10 to 50 times higher than the general CPU. Ultra DSP technology, a single DSP chip can also provide a dual function of the processor and drive interface to reduce the use of other electronic components, which can greatly improve the speed and reliability of the hard disk. Interface technology can greatly improve the maximum external transmission rate of the hard disk, the biggest benefit is that data can be directly transmitted from the hard disk to the main memory without occupying more CPU resources, and improving system performance. Hard disk surface temperature: Refers to the temperature generated during hard disk to increase the temperature of the hard disk sealing. The temperature generated during the hard disk will affect the data read sensitivity of the thin film magnetic head (including MR head), so the hard disk having a lower temperature of the hard disk has a better data read, write stability. Max Full Seek Time: Refers to the full time to move the magnetic head until finally find the required data blocks. Interface technology: Oral technology can greatly improve the maximum external data transfer rate of the hard disk, and now the Ultraata / 66 that is generally used has greatly improved the performance of the E-IDE interface. The so-called Ultradma66 refers to a synchronization of Intel and Quantum design. DMA protocol. The hard disk of this technology is used in conjunction with the corresponding chipset, and the maximum transmission speed can be increased from 16Mb / s to 66 ms / s. Its maximum advantage is to liberate the CPU from a large amount of data transmission, you can directly transfer data from HDD to the main memory without occupying more CPU resources to a certain extent, to a certain extent, to a certain extent. Performance of the entire system. Since the overall performance of the Ultraata technology is more than 20% to 60% compared to the ordinary hard drive, it has become the current E-IDE hard disk in fact standard. The interface technology of the SCSI hard drive is also growing rapidly. Ultra160 / MSCSI is introduced to the hard disk world, which has the ability to extend the performance extension of the high computing amount application field, and dealing with the server, graphics workstation, redundant disk array (RAID) such as a critical task, will therefore be improved. From the perspective of technology development, Ultra160 / MSCSI is only a ring on the road of hard disk interface. The 200MB of fiber optic technology has not reached the end, and the future interface technology will make today's users. Fiber Channel technology has the advantages of high data transmission rate, far data transmission distance, and simplified large storage system design. At present, the Fiber Channel supports 200MB of data transmission rates per second, and can accommodate up to 127 drivers on a loop, and the local cable can be run within 25 meters, and the remote cable can be run within 10 km.
Some specialized storage applications, such as small storage area networks (SAN), and digital video applications often require up to 200MB of data transfer rates and strong networking capabilities per second, and the launch of Fiber Channel technology is adapted to this requirement. At the same time, its long data transmission distance is greatly facilitating the technical implementation of remote communication. Due to the superiority of Fiber Channel technology, hard disk products that support fiber optic interface began to appear in the market. These products are generally a large-capacity hard disk, and the average finding time is short, adapted to the application requirements of high speed, high data volume, will provide good guarantees for medium high-end storage applications. IEEE1394: IEEE1394 is also known as FireWire, which is a high-speed serial bus. Existing IEEE1394 standards support 100Mbps, 200Mbps, and 400Mbps transmission rate, will reach 800Mbps, 1600Mbps, 3200Mbps, and even higher, so The high rate makes it possible to use a large-capacity storage device such as a hard disk, a DVD, a CD-ROM. IEEE1394 is expected to replace existing SCSI buss and IDE interfaces, but due to high cost and technical lack of mature, there is still only a small number of products that use IEEE1394 interfaces, and the hard disk is less. Hard disk: English "hard-disk" referred to as HD. It is a huge storage of storage, and the role is to store data required for computer runtime. The computer's hard drive is mainly composed of discs, magnetic heads, magnetic head arms, magnetic head arm service positioning systems, and underlying circuit boards, data protection systems, and interfaces. The technical indicators of computer hard drives are mainly surrounded on disk size, disk, single-disc capacity, disk speed, head technology, service positioning system, interface, secondary cache, noise, and S.m.a.r.t. Disc: All data of the hard disk is stored on the disc, and the disc is made of a hard alloy, and a glass disc is also present. The current disk size of the current hard disk products is: 5.25, 3.5, 2.5 and 1.8 inches (after two commonly used in notebooks and partial pocket precision instruments, there are often 3.5-inch discs in the desktop. The head of the head: The head of the hard disk is made by coil on the magnetic core, and the initial magnetic head is read and written, and the amplitude of the induction signal is transmitted by current. For most computers, in the process of exchange data with the hard disk, the read operation is far from writing, and read / write is the operation of two different characteristics, which enables hard disk manufacturers to develop a read / write separation head. . In 1991, IBM proposed a magnetoresistive (MR) technology-based reading technology - various anisomagnetic, magnetic heads and rotated disc phase contacts, read data by changes in magnetic field on the induction disc . In the hard disk, the disc's single-disc capacity and head technology are mutually restrictions and promote each other. AMR (Anisotropic Magneto Resistive, AMR): A magnetic head technology, AMR technology can support 3.3Gb / square inch record density, in 1997 AMR is the mainstream technology in the market at the time. GMR (GIANT Magneto Resistive, GMR): 2 times higher than the AMR technology, GMR head is made of four-layer conductive material and magnetic material film: a sensor layer, a non-conductive interposer, a magnetic property Trouble layer and a switching layer. The first three layers control the resistance of the magnetic head. In the ingress layer, the magnetic field strength is fixed, and the exchange layer of the magnetic field is maintained.
Moreover, the magnetic field strength and direction of the free layer is changed as the slight magnetization zone of the disk surface under the magnetic head is changed, and the change in the magnetic field strength and direction results in a significant change in the magnetic head resistance, and below a fixed signal voltage. You can pick the signal for the hard disk circuit processing. OAW (Optical Auxiliary Voltage Technology): The OAW, which is developed by Seagate is the direction of future magnetic head technology. OAW technology can write more than 10,5000 tracks in 1 inch wide, and single-disc capacity is expected to break through 36GB. The increase in single-disc capacity can not only improve the total capacity of the hard disk, which reduces the average seek time, but also reduces costs, improve performance. PRML (the largest propaganda of local response, Partial Response maximum likelihood): In addition to the chance of magnetic head technology, magnetic recording technology is also a major factor affecting the performance of hard disk performance. When the magnetic recording density reaches a certain degree, the phenomenon of mutual interference between the two signals will be very serious. In order to solve this problem, people have added PRML technology in the design of the hard disk. The PRML read channel method can be simply divided into two parts. The first is to digitize the signal read from the disc and abandon the standard signal without reaching the standard, and no signal output. This part is called a local response. The maximum planning part is compared to the signal model library with the PRML chip itself, identify the signal model of the PRML chip itself, and then re-combines these signals directly to directly output data. Using the PRML mode, no signal strength as the pulse detection mode is required, or the mutual interference due to the signal recording is too intensive. Advances in magnetic head technology, plus the development of current recording materials and processing technology, will increase the storage density of the hard disk to 10GB per square inch, which means that 40GB or more hard disk capacity can be implemented. Space Factor: The number of physical sectors between the two logical sectors of the hard disk track. Because the information on the hard disk is organized in the form of a sector, each sector has a number, the access operation is to pass this sector number, so use a specific spacing to give the sector number to help get The best data transfer rate. Landing area (LZ): To make the hard disk has a starting position, generally specify an inner cylinder as a landing area, which stops the hard disk head until the power is turned back before the power is turned back. The landing area is not used to store data, which can avoid the loss of data during the fire, and the power supply is avoided. Currently, a general hard disk automatically stops the head in the landing area when the power is turned off, and the old hard disk needs to perform a park command to place the head. Reaction time: Refers to the working conditions of the wheel in the hard disk. The reaction time is a most direct reaction index of the hard disk speed. The 5400 rpm hard drive has a reaction time of 5.55 ms, while 7200 rpm can reach 4.17 ms. The reaction time is the hard disk to complete the first wheel rotation using how long time. If we determine that a hard drive reaches a speed of 120 weeks, the rotation of a week will be 1/120 is 0.008333 seconds. If our hard drive is 0.0041665 seconds per week, we can also call the reaction time of this hard disk is 4.17 ms (1 ms = 1/1000 per second). Average Latency: Refers to the time when the head moves to the data where the data is located, then waits for the required data block to continue to rotate (half a ring or less) to the magnetic head at milliseconds (MS). The average incubation period is, the better, the latency is small in the hard disk read data, which is equal to having a higher hard disk data transfer rate.
SINGLE TRACK SEEK: When the head is transferred from a track to another, in milliseconds (MS). Max Full Seek: Refers to the full time that the magnetic head starts until finally find the required data block, unit is in milliseconds (ms). External data transfer rate: Burst Data Transfer Rate: Refers to the rate of reading data from the hard disk buffer, often replaced by the data interface rate, and the unit is MB / s. At present, the mainstream hard drive is Ultra ATA / 66. Its largest external data rate is 66.7Mb / s, the Ultra ATA / 100 launched in 2000. Theoretically, the largest external data rate is 100Mb / s, but due to internal data transmission The restriction of the rate is often not so high. Spindle speed: refers to the rotational speed of the motor spindle in the hard disk. At present, the spindle speed of the ATA (IDE) hard disk is generally 5400-7200 rpm. The rotational speed of the mainstream hard disk is 7200 rpm. As for the SCSI hard disk, the spindle speed of the SCSI hard disk can be reached from 7200 to 10,000 rpm. And the highest speed of the SCSI hard drive speed is up to 15,000 rpm. Data caching: Refers to the high speed memory inside the hard disk, which is temporarily stored in the computer, which is temporarily saved to read and read it. At present, the hard disk is typically 512KB-2MB. At present, the mainstream ATA hard disk is 2MB, and the highest data cache in the SCSI hard drive has now reached 16MB. Has a great advantage for the hard disk of big data cache is accessed. Hard disk surface temperature: It refers to the temperature generated when the hard disk is working, the hard disk sealing case temperature rise. The temperature generated during the hard disk will affect the data read sensitivity of the head of the head, so the hard disk having a lower temperature surface temperature is better data read, write stability. MTBF (continuous failure time): It refers to the maximum time that the hard disk is running from the beginning to the failure, and the unit is hour. The MTBF of the typical hard drive is at least 300,000 or 40000 hours. SMART (self-monitoring, analysis, reporting technology): This is now the universal data security technology used by the hard disk. When the hard disk works, the system analyzes the state of the motor, circuit, disk, and heads. When there is an abnormality, it will WARNING, some will automatically reduce and back up data. DPS (Data Protection System): Quantum built DPS in the first time in the eight-generation hard drive in the fireball, the first 300MB memory operation system of the hard disk, etc., DPS automatically detects the recovery system data within 90 seconds after the system has problems. If you don't start with the DPS floppy disk, it will automatically analyze the fault, try to ensure that the data is not lost. Data Guard: It is a unique hard disk data security technology that western data (WD). This technology can automatically automatically scan, detect, detect, and repair the sectors of the disk every 8 hours. MaxSafe: It is the technology applied by Mai Tuo in the gold diamond second-generation. Its core is to save additional ECC check digits on the hard disk, so that the read and write procedures are verified to ensure data integrity. DST: Drive self-testing technology, is the data security technology used in Sejour's hard drive, which ensures the security of the data stored in the hard disk.
DFT: Drive Health Test Technology, is the data security technology used in IBM's hard drive, which can greatly improve data security as many technologies. Noise and Shock Seismic Technology: The hard disk spindle is inevitable to generate noise during high speed rotation, and wear and heat resistance due to metal friction, "Liquid bearing motor" can solve this problem. It uses the mucosa liquid oil bearings, which can effectively reduce the above problems in an oil film. At the same time, the liquid oil bearing can also effectively absorb the vibration, so that the earthquake resistance of the hard disk is increased by one or two hundred g, so the life and reliability of the hard disk can also be improved. Quantum has applied SPS vibration protection systems after the hard disk after the Fireball Seven Generation (EX) series; Mai Tuo applied ShockBlock anti-seismic protection system in the gold diamond second generation, and their purpose is to disperse the impact energy, try to avoid the head and disk. The impact of the film; the Seashield system in the gold medal of Seagate is achieved by the protective soft cover of the shock absorbing material and the shock-shock design between the disc. ST-506/412 Interface: This is a hard disk interface developed by Seagate, first using the hard disk of this interface for Seagate's ST-506 and ST-412. The ST-506 interface is quite simple, it does not require any special cables and connections, but it supports the transmission speed is very low, so this interface is basically eliminated in 1987, using the old hard disk capacity of the interface. Most are less than 200MB. The hard drive used in the early IBM PC / XT and PC / AT machines is the ST-506/412 hard drive or called the MFM hard disk-MFM (Modified Frequency Moduction) refers to a coding scheme. ESDI interface: Enhanced Small Drive Interface interface, it was developed in 1983. It is characterized by placing the codec in the hard disk itself, rather than on the control card, the theoretical transmission speed is 2 ... 4 times the ST-506 described above, generally 10 Mbps. However, its cost is high, and there is no advantage compared to the Ide interface generated by the Ide, so it is eliminated after the 1990s. IDE and EIDE interface: Ide (Integrated Drive Electronics) actually refers to a hard drive that integrates a controller with a tray, and we often say the IDE interface, also called the ATA (Advanced Technology Attachment) interface, now PC Most of the hard drives used are IDE compatible, just use one cable to connect them with the motherboard or interface card. The practice of integrating the disk with the controller reduces the number of hard drive interfaces and length, the reliability of data transmission is enhanced, and the hard disk is made easier, because the manufacturer does not need to worry about whether the hard disk is worried about whether the hard disk is The controller produced by the manufacturer is compatible, and it is more convenient to install the hard disk. ATA-1 (IDE): ATA is the official name of the earliest IDE standard, the IDE actually refers to the hard disk itself connected to the hard disk interface. ATA has a socket on the motherboard, supports a master and a slave device, the maximum capacity of each device is 504MB, and the earliest supported PIO-0 mode (Programmed I / O-0) in ATA is only 3.3MB / s, and ATA -1 specifies three types of PIO mode and 4 DMA modes (without actual application), to upgrade to ATA-2, you need to install an EIDE adapter card.
