Basic knowledge of hard disk parameters

Hard disk is one of the indispensable hardware of computer, which plays the role of storage in computer. At present, DIY hard disk is the first choice for general solid-state hard disk, and mechanical hard disk is mostly used as storage disk. Let me show you the parameter knowledge of the hard disk, hoping to help you!

Interface type of hard disk

Hard disks can be roughly divided into ATA(IDE) and SATA, SCSI and SAS according to different data interfaces. The interface speed is not the actual data transmission speed of the hard disk. At present, the actual data transmission speed of hard disks that are not based on flash memory technology generally does not exceed 300 MB/s. ..

1.IDE hard disk interface

The English name of IDE is "Integrated Drive Electronics". IDE interface, also known as ATA interface, is an "electronic integrated driver". The traditional 40-pin parallel data cable is used to connect the motherboard and the hard disk, and the maximum interface speed is133mb/s. Because of the poor anti-interference performance of the parallel cable and the large space occupied by the cable, it is not conducive to the internal heat dissipation of the computer, and it has been gradually replaced by SAT.

2.SATA hard disk interface

SATA, the full name of Serial ATA, is an ATA interface using serial port. Because of its strong anti-interference, and the requirement of data line length is much lower than ata, it supports hot plug and other functions. The interface speed of SATA-II is 375MB/s, while the transmission speed of the new SATA-III standard can reach 750 MB/s, and the data cable of SATA is much thinner than that of ATA, which is beneficial to the air circulation in the chassis and convenient for cable arrangement.

3.SCSI hard disk interface

SCSI is the full name of small computer system interface, which has experienced many generations of development, from the early SCSI-II to the present Ultra320 SCSI and Fibre Channel, with various interface types. SCSI hard disk is widely used in workstation-class personal computers and servers, so it will adopt more advanced technologies, such as high disk speed of 15000rpm, and the CPU occupancy rate is low during data transmission, but the unit price is more expensive than ata and SATA hard disks with the same capacity.

4.SAS hard disk interface

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 6 GB/s ... In addition, the internal space of the system is improved by narrowing the connecting cable.

In addition, because SAS hard disks and SATA hard disks can share the same backplane, in the same SAS storage system, some expensive SAS hard disks can be replaced by SATA hard disks, which saves the overall storage cost. However, the SATA storage system cannot connect to the SAS hard disk.

5.USB hard disk interface

Commonly used for mobile hard disk, as shown in the figure, usb3.0 interface.

6.ZIF hard disk interface

ZIF interface hard disk is a special "PCAT" interface for Wren series 5.25-inch hard disk (the hard disk used by Compaq PC at that time) introduced by Imprimis Company. Later, the 3.5-inch hard disk also adopted this specification, ZIF: zero IF; Zero insertion force; ZIF hard disk meets the specification of parallel port interface. PATA standard specification came into being in the mid-1980s, and Seagate acquired the company "Imprimis Technology-Large Capacity Hard Disk and Components" from 65438 to 0989. A__D ZIF interface hard disk ZIF interface mechanical hard disk has basically disappeared, replaced by faster, more stable, better performance ZIF electronic hard disk, compatible with IDE transmission interface. ZIF interface electronic disk is a fast memory storage medium component with high efficiency and stability, and it is the best cost-effective memory storage medium solution at present.

7.CF hard disk interface

CF(Compact Flash) interface is mainly used for mobile and other small devices. CF interface is made according to ATA standard, but its interface is 50 pins instead of 68 pins, which are divided into two rows with 25 pins in each row.

8.CE hard disk interface

CE interface is Toshiba's 1.8 inch hard disk interface, similar to CF interface.

9. Optical fiber hard disk interface

FC (Fibre Channel), the hard disk of this interface has the characteristics of hot plug, high-speed bandwidth (4Gb/s or 10Gb/s) and remote connection when using optical fiber connection. The internal transmission rate is also higher than that of ordinary hard disk. Limited by its high price, it is usually used in the field of high-end servers.

What parameters should I pay attention to when buying mechanical hard disks?

Mechanical hard disk

1. Select the appropriate capacity as required.

When buying a mechanical hard disk, the first thing to consider is the capacity, which directly determines the size of the storage space used by users, so the capacity selection of the mechanical hard disk mainly depends on the purpose. Now 1TB mechanical hard disk has become the mainstream first choice. If the storage capacity is large, you can match your own capacity as needed, such as 2T, 3T and 4T.

For mainstream users, among many mechanical hard disk capacities, 1TB and 2TB are the most cost-effective mechanical hard disk capacities, which is also the best choice.

2, mechanical hard disk speed

The rotating speed of mechanical hard disk is expressed in Revolutions Perminute, and the unit is RPM, which is the abbreviation of revolutions per minute. The larger the RPM value, the faster the internal transmission rate and the shorter the access time, and the better the overall performance of the mechanical hard disk. The higher the rotational speed of the mechanical hard disk, the shorter the seek time of the mechanical hard disk, the higher the data transmission rate and the better the performance of the mechanical hard disk. At present, the mainstream speed of mechanical hard disks on the market is 7200 rpm.

The rotating speed of the mechanical hard disk refers to the rotating speed of the internal motor spindle, that is, the maximum rotating speed of the mechanical hard disk in one minute. The rotating speed is one of the important parameters that determine the speed of the mechanical hard disk and directly affects the speed of the mechanical hard disk. The faster the rotation speed of mechanical hard disk, the faster the reading and writing speed, but the higher the calorific value.

The performance difference of mechanical hard disk is mainly in the performance of random read-write seek time. The lower the value of random seek performance, the better, which is also the performance that can be directly experienced in the daily application speed of mechanical hard disk. Whether it is the startup of Windows system, the reading and writing of a large number of fragmentary files, the startup time of various softwares, etc. , which is directly related to random read/write time. This is the CPU, and the memory performance can't be changed, so many users start to choose solid-state hard drives.

3. Cache size of mechanical hard disk

In addition to the rotational speed, the cache size of the mechanical hard disk is also an important parameter that affects the speed. When the mechanical hard disk accesses fragmentary data, it is necessary to constantly exchange data between the hard disk and the memory. If the mechanical hard disk has a large cache, fragmentary data can be temporarily stored in the cache to reduce the load of the system and improve the data transmission speed.

At present, the cache capacity of the mainstream 1T, 2T and 3T mechanical hard disks on the market is generally 64MB, but there are some 32MB low-capacity mechanical hard disks, such as 500GB, and some 256MB high-capacity mechanical hard disks, such as 4T mechanical hard disks. The larger the cache, the faster it is.

4. The greater the storage capacity of each disk, the higher the performance.

In daily application, we can directly feel the difference of mechanical hard disk performance, except the seek performance, which is the continuous transmission rate. In different applications, their performance is different. Before explaining the continuous transmission rate, let's talk about the storage capacity per disk which is closely related to its performance.

Before the emergence of vertical recording technology, the capacity and performance of mechanical hard disks reached a bottleneck, and it was not until 2006 that mechanical hard disks using vertical recording technology began mass production that this bottleneck was alleviated.

At present, in terms of storage capacity per disk, the larger the single disk capacity of mainstream mechanical hard disks, the more data they can store. The traditional mechanical hard disk is mainly composed of magnetic disk and magnetic head. Due to the limitation of volume, the number of disks that can be placed in each mechanical hard disk cavity is limited. In order to increase the capacity of mechanical hard disk in limited disk, we can only rely on increasing the storage density of disk. Through vertical recording technology, not only the capacity of optical disc has been promoted to a new height. At the same time, due to the increase of disk data density, the continuous transmission rate of mechanical hard disk has also been improved qualitatively.

Due to the use of disks with higher track density and larger storage capacity per disk, the average continuous transmission rate in software testing has increased by more than 25%. The application that can experience this performance improvement most is the large-capacity file copying between mechanical hard disks. Like some CD images and HD video files, when copying between two mechanical hard disks, this 25% performance improvement means that the waiting time of 1/4 can be saved, which greatly improves the efficiency.

5, mechanical hard disk interface type

The interface of the mechanical hard disk is connected with the motherboard, which is used to transfer data between the cache and memory of the mechanical hard disk. The interface of the mechanical hard disk determines the connection speed with the computer.

At present, the mainstream interface of mechanical hard disk is sata3 type, and the old interfaces are IDE, sata 1 and sata2. At present, all new mechanical hard disks are SATA3 interfaces. Generally speaking, sata 1, sata2 and sata3 interfaces can be compatible with each other. SATA 1, SATA2 and SATA3 have no difference in appearance. The appearance and circuit of the interface are the same, mainly because of different transmission rates and different control chips.

SATA 1.0: the theoretical transmission speed is1.5 gbit/s.

SATA2.0: theoretical transmission speed is 3gbit/s.

SATA3.0: the theoretical transmission speed is 6 gbit/s.

In addition, the IDE interface belongs to the old hard disk interface. The theoretical transmission speed of IDE is 100 or 166MB/S, which is relatively slow, so it has been eliminated, and the current motherboards do not support IDE.

Summary:

The above is the knowledge of purchasing mechanical hard disks shared by the installation house. When purchasing mechanical hard disks, we need to pay attention not only to the capacity, but also to the cache and speed, which determine the transmission speed. As for mechanical hard disk brands, we give priority to Seagate and Western Digital.

Computer Hard Disk Errors and Handling Methods

First: the system does not recognize the hard disk.

First of all, a common fault problem is that the hard disk can't start, and it can't enter the C disk when starting from the A disk. The existence of the hard disk can't be found by using the automatic monitoring function in cmos. This kind of failure will appear on the connecting cable or ide port, and the failure rate of the hard disk itself is very small. If the hard disk cable is unplugged again or the ide port and cable are replaced for replacement test, the fault will be found soon. The newly connected hard disk is not recognized, and another reason is the master-slave line on the hard disk. if

The second type: boot failure caused by the main boot program.

Let's talk about the second question. The main boot sector of hard disk is the most sensitive part of hard disk, and the main boot program is a part of it, which is mainly used to detect the correctness of hard disk partition, determine the active partition, and hand over the boot right to dos or other operating systems of the active partition. This program will not be able to start from the hard disk, but it can be read and written from the soft area or the optical area. The repair method is also very simple. It is most convenient to use fdisk under the high version of dos. When running with the parameter /mbr, the hard disk master boot program will be directly replaced (rewritten). In fact, the main boot sector of the hard disk is established by this program, and fdisk.e__e contains a complete hard disk main boot program. Although the dos version is constantly updated, the hard disk master boot program has not changed, starting with dos 3. _ _ At present, windos 95 is used for dos. So as long as you find a dos startup disk startup system and run this program, you can repair it. In addition, other tools such as kv300 also have this function.

Third: the failure caused by cmos.

The failure caused by cmos mainly refers to the type of hard disk. Now the machine can automatically detect the type of hard disk. Connecting a new hard disk or replacing a new hard disk requires resetting the type through this function. Of course, some types of motherboards can automatically identify the type of hard disk. If the hard disk type is wrong, the system can't be started seriously, but sometimes it can be started. There will also be reading and writing errors. For example, if the type of hard disk in cmos is smaller than the actual hard disk capacity, the sectors behind the hard disk cannot be read or written. If it is multi-partitioned, a single partition will be lost. There is another reason, because the current ide supports logical parameter types, and the hard disk can be normal, lba, large, etc. If you install data in general mode, but change it to other modes in cmos, there will be errors in reading and writing hard disk, because its physical and geological mapping relationship has changed.

Fourth: partition table error boot failed.

The fault severity of partition table errors is different. If there is no active partition sign, the computer can't start. However, after booting the system from the soft or light area, the hard disk can be read and written, and can be repaired by resetting the active partition through fdisk. If the partition type is wrong, the partition will be lost. The fourth byte of the partition table is the partition type value, and the normal bootable basic dos partition value greater than 32mb is 06. The extended dos partition value is 05. If you change the basic dos partition type to 05, you can't start the system, and you can't read and write the data inside. If 06 is changed to a type that dos doesn't know, such as efh, dos thinks that the partition is not a dos partition and can't read or write. Many people will use this type of value to realize the encryption technology of a single partition. Restoring the original correct type value can restore the partition to normal. There are also the start or end addresses of other data record partitions in the partition table. The damage of these data will cause confusion or loss of partitions, which cannot be restored manually. The only way is to write back the backup partition table data or get the partition table data from other hard disks of the same type and partition conditions. Otherwise, other data will be lost permanently. When operating the main boot sector, tools and software such as nu can be used, which is very convenient to operate. You can directly read, write or edit the main boot sector of the hard disk. You can also use debug to operate, which is not only cumbersome but also risky.

Fifth: Boot failure caused by dos boot system.

Dos boot system is mainly composed of dos boot sector and dos system files. System files mainly include io.sys, msdos.sys and command.com, while command.com is the shell file of dos boot system, so it is feasible to replace it with other files. By default, it is a necessary file for dos startup. In the dos system that comes with windows 95, Msdos.sys is a text file, which is necessary to start windows. However, this file is not needed when only dos is started. When dos boot is incorrect, you can boot the system from floppy disk or CD, and then use sys c: to transfer the system, including boot sector and system files, and repair the system.

Sixth: Hard disk failure caused by incorrect partition valid flag.

An important problem of hard disk is its last two bytes: 55aah, which is a valid symbol of sector. When booting from hard disk, floppy disk or CD area, these two bytes are detected, and if there are any, the hard disk is considered to exist. Otherwise, the hard disk will not be recognized. This flag will be transferred to rom basic when booting from hard disk or prompting to put in floppy disk. When starting from floppy disk, it cannot be transferred to hard disk. This can be used for the encryption technology of the whole hard disk. Debugging methods can be used for recovery. In addition, such a flag also exists in the dos boot sector. When the dos boot sector has no boot flag, the system startup will be displayed as "Lack of operating system". The repair method can be the main boot sector repair method, but the address is different. The more convenient method is to use the following common dos system repair methods.

Seventh: Fat table leads to reading and writing failure.

Fat table has the function of storing data addresses, in which each file has a set of connected fat chains to specify its cluster address. The damage of fat table means the loss of data. Fortunately, the dos system itself provides two fat tables. If the currently used fat table is damaged, the second one can be used for rewriting repair. However, for disks with different specifications, the length of the fat table and the address of the second fat table are not fixed. Therefore, it is necessary to find its correct position correctly when repairing, because some tools and software such as nu have such repair function, which is very convenient to use. You can also use debug to achieve this operation, that is, use its m command to move the second fat table to the first table. If the second fat table is also damaged, the hard disk cannot be restored to its original state, but the data of the file is still stored in the data area of the hard disk. Can be repaired with Chkdsk or scandisk command, and finally _ _. Get the chk file, and the sector data of the lost fat chain is here. If it is a text file, you can extract it and merge the complete file. If it is a binary data file, it is difficult to recover the complete file.

Eighth: Boot failure caused by directory table corruption.

A directory table is a place where the file names and other data of files on the hard disk are recorded. One of the most important items is the initial cluster number of this file. There is no automatic backup function in the directory table, and a large number of files will be lost if the directory is damaged. The solution is to use the above chkdsk or scandisk program to search for chk files from the hard disk, because the first cluster number will be lost when the directory table is damaged. Therefore, when fat is damaged, chk files are generally complete file data, and each chk file is a complete file. Most files can be restored by changing their original names.

Ninth: recovery of formatted hard disk data

Usually, in the high version of dos, the format operation format establishes the information of the recovered formatted disk by default, which is actually the dos boot sector of the disk. Because the following sectors are rarely used, the contents of the fat partition table and the directory table are all copied to the last sector of the disk, but the contents of the data area will not change. You can restore the original file allocation table and directory table, thus completing the recovery of hard disk information. In addition, dos also provides miror command to record the current disk information, which is very useful for recovery after formatting or deletion.

Tenth: data recovery when the partition is deleted by mistake

When the partition is deleted by mistake, the data plane phenomenon is that the data in the hard disk has completely disappeared, and the invalid drive will be displayed when it is not formatted. Fdisk only rewrites the contents of the main boot sector (sectors 0, 0, 0, 1) of the hard disk, which is the embodiment of its working principle. Specifically, it is to delete the partition table information of the hard disk, but the data of any partition in the hard disk will not change. At this point, you can try to restore the partition table data and the original partition, that is, the data, according to the above method of repairing the partition table error, but only after partitioning or rebuilding the partition. If the partition has been formatted, you must restore the partition before you can continue to restore the partition data.

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