[Microsoft] [odbc SQL server Driver] [SQL server] cannot open the database &; quotmsdb & ampquot。 The recovery operation has put the

Solid-state hard disk or solid-state drive, also known as electronic hard disk or solid-state electronic disk, is a hard disk composed of control unit and solid-state storage unit (DRAM or FLASH chip). Because the solid-state hard disk has no rotating medium of ordinary hard disk, it has excellent earthquake resistance.

IDE flash drive (serial ATA flash drive): Flash chips are used as storage media, which is what we usually call SSD. Its appearance can be made into various shapes, such as notebook hard disk, micro hard disk, memory card, U disk and so on. The biggest advantage of this SSD is that it can be moved, data protection is not controlled by power supply, and it can adapt to various environments, but its service life is not high and it is suitable for individual users. In the solid-state hard disk based on flash memory, storage units are divided into two categories: SLC (single layer unit) and multi-layer unit (multi-layer unit). SLC is characterized by high cost, small capacity but fast speed, while MLC is characterized by large capacity and low cost but slow speed. Each cell of MLC is 2 bits, which is twice that of SLC. However, due to the large amount of data stored in each MLC memory cell and the relatively complex structure, the probability of errors will also increase. Solid-state hard disk must be corrected, which leads to its performance lagging far behind SLC flash memory with simple structure. In addition, the advantage of SLC flash memory is that the number of copies is as high as 100000 times, which is 10 times higher than MLC flash memory. In addition, in order to ensure the life of MLC, the control chip verifies the intelligent wear-leveling algorithm, recovers the data of Cixi hard disk, and makes the write times of each storage unit evenly shared, reaching 6.5438+0.0000 hours of time between failures (MTBF).

Solid state hard disk based on DRAM

Solid-state hard disk based on DRAM: As a storage medium, DRAM has a narrow application range at present. It imitates the design of traditional hard disk, can be set and managed by file system tools of most operating systems, and provides industrial standard PCI and FC interfaces for connecting hosts or servers. The application mode can be divided into SSD hard disk and SSD hard disk array. It is a high-performance memory with long service life. The fly in the ointment is that it needs an independent power supply to protect data security.

Advantages of SSD

Compared with ordinary hard disks, solid-state hard disks have the following advantages:

Start quickly

There is no process of motor accelerating rotation.

Small read delay

No head, fast random reading, minimum reading delay. According to related tests, under the same computer configuration, it only takes 18 seconds for a notebook with solid-state hard disk to appear on the desktop, while it takes 3 1 second for a notebook with traditional hard disk, almost half the difference.

Fragments do not affect the read time.

A relatively fixed reading time. Because the addressing time is independent of the data storage location, disk fragmentation will not affect the reading time.

Fast writing speed

The writing speed of solid-state hard disk based on DRAM is extremely fast.

No noise

Because there is no mechanical motor and fan, the noise value is 0 decibel when working. Some high-end or large-capacity products are equipped with fans, so it will still produce noise.

lower heating value

Low-capacity SSD based on flash memory has low energy consumption and low calorific value, but high-end or large-capacity products have high energy consumption.

No mechanical failure will occur.

There are no mechanical moving parts inside, so there will be no mechanical failure and no fear of collision, impact and vibration. In this way, the normal use of the notebook computer will not be affected even if it moves at high speed or even tilts, and the possibility of data loss can be minimized when the notebook computer accidentally falls or collides with hard objects.

Wider operating temperature range

A typical hard disk drive can only work in the range of 5 to 55℃. But most SSDs can work at-10~70℃, and some industrial SSDs can also work at -40~85℃ or even higher (for example, the temperature of Runxin military products is -55~ 135℃).

Small volume light weight

Low-capacity SSDs are smaller and lighter than those with the same capacity. However, this advantage gradually weakens with the increase of capacity. Up to 256GB, SSD is still lighter than ordinary HDD with the same capacity.

Disadvantages of solid-state hard disk

Compared with traditional hard disks, solid-state hard disks have the following disadvantages:

High cost

The price per unit capacity is 5~ 10 times (based on flash memory) or even 200~300 times (based on DRAM) of the traditional hard disk.

low volume

At present, the maximum capacity of SSD is much lower than that of traditional HDD. The capacity of traditional hard disks is still growing rapidly. It is said that IBM has tested a 4TB traditional hard disk.

Easily influenced by the outside world

Unlike traditional hard disks that are shielded in faraday cage, solid-state hard disks are more susceptible to some external factors. Such as power failure (especially the solid-state hard disk based on DRAM), magnetic field interference, static electricity, etc.

Limited write life

Limited write life (based on flash memory). The write life of general flash memory is 1 0,000 to 1 0,000 times, and that of special flash memory can reach 1 0,000 to 5,000 times. However, some parts of the file system, such as the file allocation table, will still exceed this limit throughout the life cycle of the computer. The dedicated file system or firmware can share the write location, so that the overall life of the SSD can reach more than 20 years.

Data is difficult to recover.

It is difficult to recover data after it is damaged. Once the hardware is damaged, if it is a traditional disk or tape storage method, some data may be saved through data recovery. But if it is solid-state storage, once the chip is damaged, it is almost impossible to retrieve the data in the chip that is broken into several petals or broken by current. Of course, this deficiency can also be made up by sacrificing storage space. The principle of backup mainly realized by RAID 1 is the same as that of traditional storage backup. Because the cost of SSD is very high at present, this way of backup is still relatively expensive.

This kind of battery has short battery life.

According to the actual test, the battery life of the notebook computer using solid-state hard disk is shorter than that of the 2.5-inch traditional hard disk using 5400RPM under idle or low load operation.

Higher energy consumption

SSD based on DRAM consumes more energy than traditional HDD at any time, especially when it is turned off, otherwise data will be lost.

It is possible to fake death when running under Windows XP system.

According to user feedback, SSD using MLC will appear suspended animation when running under Windows XP system. This is because the file system mechanism of Windows XP system is not suitable for SSD. In Windows 7, SSD is optimized, and traditional hard disk mechanisms such as SuperFetch, ReadyBoost, startup and program prefetch are disabled, which can give full play to the performance of SSD.

Comparison of advantages and disadvantages between solid-state hard disk and traditional hard disk

project

Solid state disk

Traditional hard disk

capacity

fewer/ lesser

big

price

high

low

random access

in seven-league boots

ordinary

write time

SLC: more than 654.38 million times

MLC: 10000 times

infinite

Intra-disc array

can

Extremely difficult

Working noise

not have

have

Working temperature

Extremely low

More obvious

be shockproof

very good

conflict

data recovery

difficult

can

weight

light

heavy

[3]

The above table is a comparison of the characteristics of solid-state hard disk and traditional hard disk. It can be seen that compared with the traditional mechanical hard disk, the solid-state hard disk has the following advantages:

1. Access speed: SSD solid state drives use flash memory as storage medium, which is faster than mechanical hard drives and the seek time is almost zero. When used as a system disk, this feature can obviously speed up the startup of the operating system and software.

2. Seismic performance: SSD solid state hard disk has no mechanical structure at all, and it is not afraid of vibration and impact, and it is not necessary to worry about the inevitable data loss caused by vibration.

3. Heating power consumption: SSD solid state drives are different from traditional hard disks and solid state drives, and there is no high-speed rotation of disks, so the heating is obviously lower than that of mechanical hard disks, and the power consumption of FLASH chips is extremely low, which means an increase in battery life for notebook users.

4. Use noise: SSD solid state hard disk has no disk body mechanism, and there is no sound and noise of head arm seeking when rotating at high speed, so SSD will not produce noise at all when working.

However, although the performance of SSD is attractive and has many advantages, the disadvantages such as price, capacity and limited data reading and erasing times should not be underestimated:

1. Write speed: At present, write speed is the bottleneck of most SSD products, especially small files, which is far from enough, which is related to the characteristics of flash memory chips.

2. Service life: Flash memory chips have a service life, and its average working life is much lower than that of mechanical hard disks, which brings certain risks to solid-state hard disks as storage media.

3. Cost-effectiveness: At present, the price of solid-state hard disks is still relatively expensive, which is dozens of times that of traditional hard disks, and ordinary consumers can't afford it.

Solid state hard disk products

There are 3.5-inch, 2.5-inch, 1.8-inch solid-state hard disk products at present, and the capacity is generally 160GB~ 1TB, which is much larger than the general USB flash drive. Interface specifications are consistent with traditional hard disks, including UATA, SATA, SCSI, etc.

For example, the product line of RunCore, a domestic brand manufacturer, covers all standard interface SSDs except the mini PCIe interface, Zif interface and1.8 "LIF interface specially designed for Mac air.

At CES 2008, BitMicro Networks, a professional SSD manufacturer, demonstrated the internal structure of a professional SSD product with SCSI interface (see right). This product has 32 NAND flash memory chips, and TSOP package is soldered on PCB. According to BitMicro's data, the average price per GB of this product is about 10, which is about five times that of mainstream mechanical hard disks.

In 2008, Netac also launched the so-called first domestic solid-state hard disk product. Yi claimed that it had launched the first domestic solid-state hard disk product in 2007. Followed by Zhongji Ye Wei, it also launched the fastest SSD product in the world. Magnesium can be called SSD with the speed of 1GB/S (using SSD as an array).

Security of solid-state hard disk

Compared with traditional hard disk drives, solid-state hard disk drives may provide better data security, but experts say that they will not completely erase data and are weak in resisting physical attacks from high-output lamps such as ultraviolet lasers from light sources.

Although it is relatively expensive and durable, solid state drives are still popular, especially on portable computers, because they have the characteristics of low power consumption and fast data access. Experts said that with the wide application of SSD technology and its penetration into other handheld devices such as smart phones, protecting the data security on SSD will become a more concerned issue.

Jim Handy, president of Objective Analysis, a semiconductor research and consulting company, said that many solid-state hard drives use industry-standard NAND flash chips specially designed for cameras and MP3 players, so they have no physical security holes and will not prevent them from being removed from the storage case. Hackers can easily separate NAND chips from solid-state hard drives, and then use flash memory chip programs to read the data. Once the data is read, you can use data recovery software to reorganize the files. Handy said: This process is really nothing complicated. Bunnie, a hacker who specializes in attacking chips in Bunnie Studio, a blog site, said that another physical attack includes using an ultraviolet laser to remove the lockbit or encryption lock, which is located on the fuse of the chip to protect the SSD drive. After the lock bit is removed, the data array on SSD can be read by standard methods. Bunnie said: Once the data is unlocked, you don't need any special equipment to read the data array. For example, a data array can be read by using a conventional ROM reader, which usually means burning and checking unsafe ROM devices. Craig Rawlings, marketing director of Kilopass, said that in order to reduce the possibility of hackers stealing data, encryption locks can be integrated into solid-state hard disk drive controller devices to solve the problem of disk encryption from the hardware layer, and Hangzhou data can be recovered. Kilopass sells products that use Super Persistent Programmable Memory (XPM) technology to store encryption locks on system-on-chip devices.

Although the encryption lock will also be attacked, experts believe that encryption is the first priority to protect the data security on the solid state drive. Many companies, including Safend and Encryptx, have products in this field, which can encrypt data on storage devices such as SSD. Sean Barry, senior engineer of Kroll Ontrack data recovery, said that encryption adds another line of defense, so hackers must bypass the encryption layer and controller, and then reassemble the original data to successfully steal data. This takes some time, during which the data may be invalid or lose its value. Encryption also makes it easier to erase files on SSDs. Kyle Wiens, CEO of iFixlt, said that like hard drives, although SSDs create multiple file backups, encryption software can help you erase protected files. Wiens said: Every time you write data to the SSD, it may be written to another place on the HDD, and then you can modify the directory table. In this way, it forgets the address where the data was stored before. A user may delete a file, but the copy on another partition may still be safe. Wiens said that the wear-leveling function of SSD (based on an algorithm) can erase and write data evenly on all memory chip units, so that the aging speed of each memory chip unit can be balanced, which makes it difficult to completely erase files. Intel Fellow-Knut Grimsrud said that some encryption software will monitor the wear leveling process to track the traces of files, and then you can use the secure erase command to delete these traces. Secure erasure is a command to delete files safely, which needs the support of encryption software. Grimsrud said: If all software writes data on the top layer of logical block addressing (LBA), I think it may be inefficient on the solid-state hard disk, because it may lose the efficiency improvement brought by previous wear balancing or other similar functions, and the software does not know this. Logical block addressing (LBA) specifies the storage address of a data block on a storage device.

In a word, the data on the SSD is easier to delete than the data on the HDD, which has both advantages and disadvantages. According to Barry of KrollOntrack, data is stored in pipes of solid-state disk drives. If the test tube is eliminated, the data will be washed away. On the hard disk drive, in order to prevent the data from being read, the data must be overwritten or physically damaged. Barry said that from a fast point of view, data refresh has its own advantages, but from a bad point of view, the data on solid-state drives are often random and easy to lose.

Limitations of SSD solid-state storage

Although SSD seems to have great advantages over disk technology, it also has some shortcomings. The first is expensive, because the cost of memory is almost 100 times that of disk storage. Secondly, some of them are composed of volatile DRAM, and once the power is cut off, the data will be lost permanently. In order to avoid data loss, these SSDs should be protected by backup batteries. Finally, because SSD is not a cache, it will not refresh a small number of data blocks to non-volatile storage, but copy the entire contents of SSD. Although the capacity and continuous write transfer rate of the target disk drive or subsystem are different, a reasonable estimate for this operation is 30-40 MB/s.

One of its management methods is to use disk drives to mirror SSD. However, it needs extra overhead to handle the I/O of the mirror drive, which has a negative impact on the overall I/O transmission rate of S&D. But in any case, it takes very little time, at least when the mirror write operation to the mirror disk is completed.

For some reasons, including chip density and heat dissipation performance, the capacity of solid state drives is always smaller than that of disk drives. Considering the disk subsystem, the capacity difference is even greater. This means that applications using SSD are limited by SSD storage capacity. However, it is worth pointing out that SSD can be used in disk subsystem to provide high-performance storage.

To sum up, the higher price hinders the popularization of SSD solid state hard disk, and the price is several times or even dozens times higher than that of mechanical hard disk with the same capacity.

At present, the capacity of SSD solid state hard disk is small, and the current hard disk is as high as 5 12gb, while the maximum capacity of SSD solid state hard disk is only 5 12gb, which is very expensive. Lack of terminal equipment support is another major problem faced by SSD solid state drives.

Although the current SSD is still restricted by factors such as cost and capacity, with the popularity of Windows 7 operating system, the specifications of SSD will be continuously upgraded, and the development speed will be further accelerated, and the future of SSD will still be brilliant.

Optimization of Solid State Disk Technology by Windows 7 System

Although SSD still has many shortcomings, with the continuous improvement of SSD technology research and development and the launch of Microsoft's latest Windows operating system Windows 7, the optimization of SSD is stronger, and some shortcomings of SSD have been solved.

Windows 7 system better improves the technology of SSD performance and life. Without any user setting, the system will automatically identify whether the storage device is a mechanical hard disk or a solid state hard disk. If it is a solid state drive, the defragmentation function will be turned off to prevent the solid state drive from repeatedly reading and writing, thus reducing the loss of the solid state drive chip. Trim instruction can effectively prevent the speed of SSD from decreasing after long-term use and prolong the service life of flash memory.

By default, Windows 7 can automatically detect SSD devices, and disable the automatic disk defragmentation function of devices in scheduled tasks, which can greatly reduce the loss of SSD in daily use and increase its service life. You know, according to the current SSD products, the write life of mainstream MLC chip SSD is only 10000 times, while the expensive SLC chip SSD is only 65438+ 10,000 times.

When will SSD be popularized?

There is no doubt that SSD is the pioneer of the next generation storage media. With the increasing demand for speed and stability, the rising space of SSD will be very large. However, although the performance advantages of SSD make its future growth potential not to be underestimated, and the speed of SSD listing seems to be much faster than expected at present, there is obviously a considerable distance from the popularization of the whole people and the complete replacement of traditional mechanical hard disks.

Domestic solid-state hard disk research and development company

1. Hunan Yuan Ke High-Tech Co., Ltd.

R&D personnel mainly come from National University of Defense Technology and social recruiters. Mainly used in military, industrial and consumer fields.

Provide customized or unique solid state drives with independent intellectual property rights.

2. Yizheng Storage Technology (Shenzhen) Co., Ltd.

Samples will be delivered in 2007.

3. Wuhan gujie data technology co., ltd.

Samples will be delivered in 2008.

4. Huasai

Samples will be delivered in 2008.

5. Huaheng Ye Wei (Sendong) Technology Co., Ltd.

For military enterprises and server applications, a solid-state hard disk with "one-click destruction" of data was introduced. The capacity is as high as 1TB, and the reading and writing speed is greater than 250MB.

6. Shenzhen Lee Electronics Co., Ltd.

A company specializing in the production of SLC (enterprise-level) solid state drives. Relatively high cost performance