I want to use a small capacity SSD as a system disk, large capacity ordinary hard disk for software and other things, so that the computer running speed is good!

The SSD consists of a number of disks made of aluminum or glass. These disks are covered with ferromagnetic material. The vast majority of hard drives are stationary drives, permanently sealed in a hard disk drive. However, removable hard drives are becoming more popular and more varied.

The vast majority of hard drives used in desktop computers have either an IDE interface or a SCSI interface, which has the advantage that up to seven different devices can be connected to the same controller panel. Since the hard disk rotates at a constant high speed of 3,000 to 10,000 revolutions per second, it takes only a short time to read data from the hard disk. In laptop computers, the hard disk can stop spinning when it is idle in order to extend battery life. Older hard drives had storage capacities as small as 5MB and used platters up to 12 inches in diameter. Today's hard drives, with storage capacities of tens of gigabytes, use platters that are typically 3.5 inches in diameter for desktop computer hard drives and 2.5 inches in diameter for laptop computer hard drives. New hard drives are generally low-level formatted in the assembly plant, with the goal of storing some of the original sector identification information on the drive.

Sata (serial ata), the serial ata interface, was pioneered by intel in the early 2000s as a new hard disk interface technology. While compared to traditional parallel ata storage devices, sata hard disks have unparalleled advantages. The real serialization of the disk system is the first from the motherboard side, as early as in the serial hard disk formally put on the market before the motherboard sata interface has been ready. But in the intel ich5, sis964 and via vt8237 these real support sata south bridge chip appeared before the motherboard sata interface is realized through the third-party chip. These chips are mainly siliconimage's sil 3112 and promise's pdc20375 and pdc20376, which are based on the pci bus, and some products are also made into specialized pci raid controller cards.

Maintenance of the hard disk

Hard disk as a computer parts in the very durable equipment, good maintenance, you can generally use a 6 to 7 years, the following to say how to properly maintain the hard disk.

The maintenance of the hard disk should be divided into two aspects, first of all, from the perspective of the hardware, especially those super computer DIY players to pay attention to the following issues. They usually do not use the chassis, the computer are placed on the desktop on the one hand conducive to heat dissipation, on the one hand, to facilitate the disassembly of the convenience, and so the chances of damage to the hardware greatly increased, especially hard disk, because when the hard disk begins to work, generally in the high-speed rotation in the desktop is not fixed, unstable and most likely to lead to the head and the platters of the hard disk damage caused by violent friction. There is also the need to prevent the computer from being used when the temperature is too high, too high a temperature will not only affect the normal work of the hard disk, but may also lead to damage to the hard disk.

High temperatures affect the data-reading sensitivity of thin-film heads, change the clock frequency of crystal oscillators, cause hard disk circuitry to malfunction, and cause recording errors in the magnetic media due to thermal expansion.

The high temperature is not suitable, too low temperature will also affect the hard disk work. So in the air-conditioned room should also be careful not to lower the temperature of the air-conditioning too much, which will produce water vapor, damage to the hard disk. In general, it is appropriate to keep the room temperature at 20 to 25 degrees Celsius. Next we talk about the use of the process of hard disk.

Many friends in the use of computers are not a good habit, finished the computer, shut down the computer has not been completely shut down on the unplugging of the power supply, there are people in the use of computers directly off the switch, the hard disk at this time has not been reset, so shut down must pay attention to the panel of the hard disk indicator whether it is still blinking, only when the hard disk indicator stops flashing, hard disk end of the read and write before you can turn off the computer! The power switch of the computer is a good habit to develop.

Some people pay a lot of attention to hard disk maintenance, but due to improper operation, it will also cause a certain degree of damage to the hard disk.

Some people see the press to regularly organize the information on the hard disk, and he did not appreciate the word regular, every day after using the computer to organize a hard disk, that can improve the speed, but he did not know that this will increase the use of the hard disk, the hard disk is not only not achieve the effect of the long term, make it the opposite.

Of course, if your hard drive is not organized for a long time, if the debris has accumulated a lot of words, then we later in the access to a file, the hard drive may take a long time to read the file, not only access to the efficiency of the decline, but also the possibility of damage to the magnetic stripe. That's not the only problem we often encounter.

And then there's the fact that some of my friends copy several files at a time, and in return the hard drive screams. To "regularly" anti-virus the hard disk, such as CIH can destroy the hard disk partition table, resulting in the loss of your precious "wealth". Don't use the hard drive compression technology in the system tools, now the hard drive is very big, there is no need to save the hard drive space, not to mention that this brings the hard drive read and write data greatly slowed down, but also unknowingly affect the hard drive life.

This shows that it is very important to develop good computer habits, which will have a direct impact on the life of the computer and even the hard disk. It is important to take your time and make it a habit so that your computer will last you a long time.

Physical structure

1, heads

Heads are the most expensive part of the hard disk, but also the most important and critical part of the hard disk technology. The traditional magnetic head is a read-write electromagnetic induction head, but the hard disk read, write is two very different operations, for this reason, this two-in-one head in the design must be taken into account at the same time to read/write the two characteristics, resulting in the design of the hard disk limitations. MR heads (Magnetoresistive heads), that is, magnetoresistive heads, the use of separate head structure: write heads still use the traditional magnetic induction heads (MR heads can not write operations), read heads are used in the new MR heads, the so-called inductive write, magnetoresistive read. In this way, the design can be optimized for the different characteristics of the two separately to get the best read/write performance. In addition, MR heads sense signal amplitude through resistance changes rather than current changes, and thus are quite sensitive to signal changes, and the accuracy of read data is improved accordingly. And because the signal amplitude of reading is not related to the width of the magnetic track, the magnetic track can be made very narrow, thus improving the disk density, up to 200MB/inch 2, while the use of traditional heads can only reach 20MB/inch 2, which is also the main reason why the MR head is widely used. Currently, MR heads are widely used, and GMR heads (Giant Magnetoresistive heads), which are made with multilayer structures and materials with better magnetoresistive effects, are also becoming popular.

2. Magnetic tracks

When a disk is rotating, if the heads are kept in one position, each head will make a circular track on the surface of the disk, and these circular tracks are called magnetic tracks. These tracks are not visible to the naked eye, because they are only some magnetized areas on the disk surface magnetized in a special way, and the information on the disk is stored along such tracks. Neighboring tracks are not right next to each other because the magnetization units are too close to each other, which makes it difficult to read and write to the heads. A 1.44MB 3.5-inch floppy disk has 80 tracks on one side, whereas the track density on a hard disk is much greater, usually thousands of tracks on one side.

3, sector

The disk is divided into a number of arcs of each track, these arcs is the sector of the disk, each sector can store 512 bytes of information, the disk drive to read and write data to the disk, to the sector as a unit.1.44MB 3.5-inch floppy disk, each track is divided into 18 sectors.

4. Column

Hard disk usually consists of a group of overlapping platters, each platter is divided into an equal number of tracks, and from the outer edge of the "0" numbering, with the same number of tracks to form a cylinder, called the disk's column. The number of cylinders on a disk is equal to the number of tracks on a disk. Since each platter has its own heads, the number of platters is equal to the total number of heads. The so-called hard disk CHS, that is, Cylinder (Cylinder), Head (Head), Sector (Sector), as long as we know the number of hard disk CHS, you can determine the capacity of the hard disk, hard disk capacity = Cylinder number of Heads number of Sectors number of 512B.

Introduction to the logical structure of the hard disk

1. hard disk parameter explanation

So far So why do we use these parameters and what do they mean? What is the range of their values?

A long time ago, when hard disks were very small, they were manufactured using a structure similar to that of floppy disks. That is, each track of a hard disk has the same number of sectors. This gave rise to the so-called 3D parameter (Disk Geometry). This is the number of heads, cylinders, sectors, and the corresponding addressing method.

Among them:

Heads indicate how many heads there are on a hard disk, i.e., how many platters there are, up to a maximum of 255 (stored in 8 binary digits);

Cylinders indicate how many tracks there are on each side of the disk, up to 1023 (stored in 10 binary digits);

Sectors indicate the number of sectors on a disk, up to a maximum of 1023 (stored in 10 binary digits);

Sector counts indicate the number of sectors on a disk, and the corresponding addressing mode. p> Sectors indicate how many sectors are on each track, up to a maximum of 63 (stored in 6 binary bits).

Each sector is typically 512 bytes, which is not theoretically necessary, but there doesn't seem to be any other value.

So the maximum capacity of a disk is:

255 * 1023 * 63 * 512 / 1048576 = 8024 GB (1M = 1048576 Bytes) or in the units commonly used by hard disk manufacturers:

255 * 1023 * 63 * 512 / 1000000 = 8414 GB (1M = 1000000 Bytes )

In CHS addressing, Heads, Cylinders, and Sectors can range from 0 to Heads - 1, 0 to Cylinders - 1, and 1 to Sectors (note that it starts at 1).

2. Introduction to the BIOS Int 13H call

The BIOS Int 13H call is a basic input/output interrupt call provided by the BIOS to reset, read/write, verify, locate, diagnose, and format disks (including hard disks and floppy disks). It uses CHS addressing, so it can access hard disks up to 8GB (1M = 1048576 bytes in this article, unless otherwise specified).

3. Introduction to Modern Hard Disk Architecture

In old hard disks, since the number of sectors in each track was equal, the recording density of the outer track was much lower than that of the inner track, thus wasting a lot of disk space (as with floppy disks). In order to solve this problem and further increase the capacity of hard disks, hard disks are manufactured in an equal density structure. This means that the outer ring has more sectors than the inner ring. With this structure, hard disks no longer have actual 3D parameters, and the addressing method has been changed to linear addressing, which means addressing on a sector-by-sector basis.

In order to be compatible with older software that uses 3D addressing (such as software that uses the BIOSInt13H interface), an address translator is installed inside the hard disk controller, which is responsible for translating the old 3D parameters into the new linear parameters. This is the reason why nowadays there is a wide range of 3D parameters available for hard disks (different operating modes, corresponding to different 3D parameters, e.g. LBA, LARGE, NORMAL).

4. Introduction to Extended Int 13H

Although modern hard disks have adopted linear addressing, due to the constraints of the basic Int 13H, programs that use the BIOS Int 13H interface, such as DOS, can only access up to 8 Gigabytes of hard disk space. In order to break this limitation, Microsoft and several other companies have developed the Extended Int13H standard (Extended Int13H), which uses linear addressing to access hard disks and therefore breaks the 8 Gigabyte limitation, as well as adding support for removable media (e.g., removable hard disks).

Basic Parameters

I. Capacity

As the data storage of a computer system, capacity is the most important parameter of a hard disk.

The capacity of a hard disk is measured in megabytes (MB) or gigabytes (GB), with 1GB=1024MB, but hard disk manufacturers usually take 1G=1000MB as the nominal capacity of the hard disk, so the capacity we see in the BIOS or when formatting the hard disk will be smaller than the manufacturer's nominal value.

For users, the capacity of the hard disk, like memory, will always be too little, not too much. Windows operating system brings us in addition to more convenient operation, but also brings the file size and the number of increasingly inflated, some applications easily eat up hundreds of megabytes of hard disk space, and there is a trend of increasing. Therefore, it is wise to buy a hard disk properly ahead of the time. The current mainstream hard disk capacity of 10G and 15G, and more than 20G high-capacity hard disk has begun to gradually popularize.

In fact, the larger the hard disk capacity, the cheaper the price per byte. For example, the Fireball 10G costs $1,000, or $100 per Gbyte, while the Fireball 15G costs $1,160, or less than $80 per Gbyte.

The capacity indicator of a hard disk also includes the single-disk capacity of the hard disk. The so-called single-disk capacity refers to the capacity of a single disk of the hard disk, the larger the single-disk capacity, the lower the unit cost, the shorter the average access time. Most hard drives on the market today have a single-disk capacity of more than 6.4G, while higher ones have reached 10G.

Two, rotational speed

Rotational speed (Rotational speed or Spindle speed) refers to the number of revolutions of the hard disk platters per minute, in rpm.

The current mainstream IDE hard disk drive on the market is generally 5200rpm or 5400rpm, and the speed of the hard disk platters is about 1.5 seconds, which is about 1.5 seconds. The speed of the mainstream IDE hard drives on the market today is generally 5200rpm or 5400rpm, with Seagate's Grizzly series and Maxtor reaching 7200rpm, the fastest speed among IDE hard drives. As for the SCSI interface hard disk, generally have reached the speed of 7200rpm, and the higher reached 10000rpm.

Three, the average access time

Average Access Time (Average Access Time) refers to the magnetic head from the starting position to reach the target track position, and from the target track to find the data sector to be read and written. the time it takes to find the data sector to be read or written from the target track.

Average Access Time reflects the read and write speed of a hard disk, which includes the seek time and wait time of the hard disk, i.e.

Average Access Time = Average Seek Time + Average Wait Time.

The average seek time (Average Seek Time) of a hard disk is the time it takes for the disk's heads to move to a specified track on the platter. This time is of course the smaller the better, the current hard disk average seek time is usually between 8ms to 12ms, and SCSI hard disk should be less than or equal to 8ms.

Hard disk wait time, also called latency (Latency), is the head has been in the to be accessed to the track, waiting to be accessed to the sector rotation to the head of the time below. The average waiting time is half of the time it takes for the disk to rotate one week, and should generally be less than 4ms.

Four, transfer rate

Transfer rate (Data Transfer Rate) hard disk data transfer rate refers to the hard disk read and write data speed, the unit is megabytes per second (MB/s). Hard disk data transfer rate includes internal data transfer rate and external data transfer rate.

Internal Transfer Rate, also known as Sustained Transfer Rate, reflects the performance of a hard disk when its buffers are unused. The internal transfer rate is largely dependent on the rotation speed of the hard disk.

External Transfer Rate, also known as Burst Data Transfer Rate or Interface Transfer Rate, is the nominal data transfer rate between the system bus and the hard disk buffer, and is related to the type of hard disk interface and the size of the hard disk cache.

Currently, the maximum external transfer rate for Fast ATA interface hard drives is 16.6MB/s, while Ultra ATA interface hard drives reach 33.3MB/s.

V. Cache

Like the RAM cache on the motherboard, the purpose of the hard drive cache is to solve the problem of mismatch between the front and back of the system, so as to improve the read and write speeds of the hard drive. problem in order to increase the read and write speed of the hard disk. Currently, most IDE hard drives have between 128K and 256K cache, while Seagate's Grizzly series uses 512K cache.

Hard drive data protection technology

The larger the capacity of a hard drive is, the more data we store on it. So how safe is it to store such a large amount of data in such an iron box? Although most hard disks today have a MTBF of more than 300,000 hours, this is still not enough for a single failure to have catastrophic consequences. Because data is the most expensive part of a PC system for many users, especially business users, they need to be able to predict failures in advance. It is this need and crisis of confidence that has driven vendors to seek a hard disk security monitoring mechanism, and thus, a series of hard disk data protection technologies have emerged.

1, S.M.A.R.T. technology

S.M.A.R.T. technology is known as Self-Monitoring, Analysis and Reporting Technology, that is, "Self-Monitoring, Analysis and Reporting Technology". In the ATA-3 standard, S.M.A.R.T. technology is formally established, S.M.A.R.T. monitoring objects include heads, disks, motors, circuits, etc., by the hard disk's monitoring circuits and the host monitoring software to monitor the object's operation and historical records and preset safety values to analyze, compare, and when there is a situation outside the range of the safety value, it will automatically send a warning to the user, and more advanced technology is also available. The more advanced technology can also alert the network administrator's attention, automatically reduce the running speed of the hard disk, transfer important data files to other safe sectors, or even back up files to other hard disks or storage devices. With S.M.A.R.T. technology, it is indeed possible to effectively predict potential hard disk failures and improve data security. However, we should also see that S.M.A.R.T. technology is not omnipotent, it can only monitor gradual failures, and for some sudden failures, such as sudden breakage of the disk, the hard disk no matter how smart can not help. So no matter what, backups are still a must.

2, DFT technology

DFT (Drive Fitness Test) technology is IBM's PC hard drive data protection technology developed by the company, it is through the use of the DFT program to access the IBM hard drive in the DFT micro-code hard drive testing, which allows users to quickly and easily detect the hard drive's operating conditions.

According to research, most of the hard disks that users send back for repair are fine on their own, and DFT reduces this by saving users time and effort and avoiding data loss due to misjudgment. It splits a separate space on the hard drive for the DFT program, which can be invoked even when the system software is not working properly.

The DFT micro-code can automatically register the error events and save the registered data to the reserved area on the hard disk. the DFT micro-code can also physically analyze the hard disk in real time, such as reading the servo position error signal to calculate the parameters of the disk exchange, servo stability, repetitive movement, etc., and give the graphs for the reference of the user or the technician. This is a completely new concept, where control signals from the hard drive subsystem can be used to analyze the mechanical condition of the hard drive itself.

And the DFT software is a stand-alone, OS-independent software that can run without any of the user's other software failing.

About Extended Partitions

Since the primary partition table can only have four partitions, which is not enough to meet the demand, an extended partition format was designed. Basically, the information of the extended partition is stored in the form of a chained table, but there are some special features. First of all, the primary partition table has a base extended partition entry to which all extended partitions belong, i.e. the space of all other extended partitions must be included in this base extended partition. For DOS / Windows, the extended partition is of type 0x05. All extended partitions other than the base extended partition are cascaded in a chained table, with data entries of the subsequent extended partition recorded in the partition table of the previous extended partition, but the space of the two extended partitions does not overlap.

An extended partition is similar to a full hard disk, which must be further partitioned to be used. However, only one other partition can exist on each extended partition. This partition is the logical disk in a DOS/Windows environment. Therefore, the partition table for each extended partition (also stored in the first sector of the extended partition) can only have a maximum of two partition data entries (including the data entry for the next extended partition).