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Good versus bad

However, it's time to move from philological and historical research to some technical details of flash devices. Like everything in our imperfect world, flash memory has both advantages and disadvantages. In short, all the pros and cons of flash devices can be summarized in the following two lists.

The advantages of flash memory:

• No additional energy is required to store data, that is, flash memory is a non-volatile device.
• Energy, however, is required to record data, it cannot be done without expenses at all, in the end, as you know, it is impossible to create a perpetual motion machine. But compared to CDs or floppy disks, the energy consumption when working with a flash device is minimal. Therefore, flash memory is very energy efficient. As a confirmation - writing data to a flash-microcircuit requires 10-20 times less energy than similar operations with a CD or floppy disk.
• Flash-microcircuit allows you to repeatedly (but, alas, not endlessly ...) overwrite data. That is, flash memory is a rewritable storage device.
• The flash drive does not contain any moving mechanical parts and devices, since it is solid-state memory. And if so, flash devices are resistant to mechanical stress: if there is no mechanics, there is nothing to break. For example, a flash drive can withstand shocks 10-20 times stronger than those that would simply “kill” a computer hard drive. And not only to withstand, but also to work in conditions of shaking and rather tough “beating”.
• Compactness is another advantage of flash-memory drives, which predetermined the use of flash-devices in various small-sized
• gadgets and "hand" devices.
• Finally, the information written to flash memory can be kept very long time(about 10, and according to some sources, up to 100 years). That is, the flash microcircuit is a device for long-term storage data.

Now the flip side of the coin, that is, the disadvantages of flash memory:

• To begin with, the main consumer drawback is that flash memory is more expensive than floppy disks, CDs and computer hard drives.
• Flash memory is significantly slower than RAM based on SRAM and DRAM chips. And even compared to hard disk flash drive is an outsider. For example, the average speed of reading data from a flash drive is 5 Mb / s, and writing is 3 Mb / s.
  At the same time, the hard disk can exchange data at a speed of about 30 Mb / s.
• Finally, one more serious drawback, which was already mentioned above, is that flash memory has a limitation on the number of rewriting cycles. The limit ranges from 10,000 to 1,000,000 cycles for different types microcircuits. And although a million write / erase operations are quite a lot, the presence of a physical limit for the use of a memory chip can be considered a serious drawback of flash devices.

Versatility

USB abbreviation means that no special "floppy drives" or adapters are required to connect these devices other than those found in every modern computer or laptop USB port. This is one of the reasons that from the very beginning of its inception, flash drives have gained great popularity among users. Almost all operating systems installed on your hardware will automatically recognize your flash drive as an additional removable drive.

Compactness

The standard size of the USB Flash-drive is 70 x 20 x 10 mm (some models are larger, some are much smaller). In this case, the weight of the flash drive does not exceed 20-30 grams.

Reliability

There are no mechanical moving parts inside the devices, which makes them more resistant to mechanical influences (vibrations and shocks) in comparison with other storage media and significantly reduces power consumption. In addition, flash drive cases are made of various shock-resistant materials (plastic, leather, metal, rubber).

Baud rate

• USB 1.1 interface - up to 12 Mbps.
• USB 2.0 interface - up to 480 Mbps.
• Announced in 2008 (but not yet put into use) USB 3.0 interface - up to 4.8 Gbps.

Volume and density of recording

Memory sizes of modern flash drives start at 256 MB. The most common capacities today are 2-4 GB. The maximum capacity is 128 GB. In other words - the amount of memory sticks for every taste and for any task, from using them as "keys" to enter databases, to storing various movies in DivX format.

At the same time, all flash drives have a high information recording density (much higher than that of CD or DVD).

Data protection

The protection of data stored on a flash drive can be done both by mechanical action and at the software level. In the first case, some flash cards have a special mechanical write-protect switch (it is indicated by two icons: an open and a closed lock). In the second case, using a special software, some or all of the data is locked with a password, and you can access this area of ​​the flash card or format it only if you know the access password.

Boot disk function

Like CDs, most USB flash drive the possibility of using them as boot device like system disk... Some manufacturers offer special software along with a flash drive that allows you to make a USB flash drive "bootable".

Efficiency in special conditions

Flash drives are designed to work flawlessly in wide range temperatures (from -40 to +70 0С) and relative humidity (5% - 90%).

Design and additional features

The appearance of flash drives is very diverse and multifaceted. This various materials cases and a wide range of colors, jewelry elements and flash drives with a transparent case filled with multi-colored liquid, in the form of a corporate logo or a dummy of any product ...

Deserve attention and additional functions non-standard flash drives: flashlight, laser pointer, flash drive ballpoint pen, flash drive silicone bracelet and much more.

Disadvantages of flash drives

Cyclic recording-erasure

Flash drives have limited number write-erase cycles before failure. The approximate number of cycles is 100 thousand. That is, if you write down and erase 1 GB information on a 1 GB flash drive 10 times a day, it will fail in 25-26 years.

Baud rate

There is an opinion that the speed of writing / reading information from a flash drive decreases over time. Perhaps this is so, but there is no official confirmation of this information yet.

Appearance

Most standard flash drives have a cap that covers the USB connector and prevents damage. The disadvantage of this flash drive element is that it is constantly lost or forgotten. Sometimes the manufacturer makes a special mechanism for hiding the connector instead of the cap - the cap cannot be lost (since it is not there), but the mechanical structure is more susceptible to wear and tear.

Considering all the above advantages and disadvantages of flash drives, one can come to the following conclusion - this type of drives is one of the most optimal devices for storing and transferring data.

We offer flash drives only with original components from manufacturers. All products have a 1 year warranty. Special attention should be paid to this, due to the massive appearance on Russian market low-quality flash drives. Our flash drives are distinguished by their high performance and absence of defects. They will support your reputation and strengthen the long-term relationship with your Partners.

We offer a variety of solutions to make products unique to your corporate identity!
Our motto is quality, individuality and practicality!

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Advantages and disadvantages of flash memory

Good versus bad

However, it's time to move from philological and historical research to some technical details of flash devices. Like everything in our imperfect world, flash memory has both advantages and disadvantages. In short, all the pros and cons of flash devices can be summarized in the following two lists.

The advantages of flash memory:

• No additional energy is required to store data, that is, flash memory is a non-volatile device.
• Energy, however, is required to record data, it cannot be done without expenses at all, in the end, as you know, it is impossible to create a perpetual motion machine. But compared to CDs or floppy disks, the energy consumption when working with a flash device is minimal. Therefore, flash memory is very energy efficient. As a confirmation - writing data to a flash-microcircuit requires 10-20 times less energy than similar operations with a CD or floppy disk.
• Flash-microcircuit allows you to repeatedly (but, alas, not endlessly ...) overwrite data. That is, flash memory is a rewritable storage device.
• The flash drive does not contain any moving mechanical parts and devices, since it is solid-state memory. And if so, flash devices are resistant to mechanical stress: if there is no mechanics, there is nothing to break. For example, a flash drive can withstand shocks 10-20 times stronger than those that would simply “kill” a computer hard drive. And not only to withstand, but also to work in conditions of shaking and rather tough “beating”.
• Compactness is another advantage of flash-memory drives, which predetermined the use of flash-devices in various small-sized
• gadgets and "hand" devices.
• Finally, information recorded on flash memory can be stored for a very long time (about 10, and according to some data, even up to 100 years). That is, a flash microcircuit is a device for long-term data storage.

Now the flip side of the coin, that is, the disadvantages of flash memory:

• To begin with, the main consumer drawback is that flash memory is more expensive than floppy disks, CDs and computer hard drives.
• Flash memory is significantly slower than RAM based on SRAM and DRAM chips. And even in comparison with a hard disk, a flash drive is an outsider. For example, the average speed of reading data from a flash drive is 5 Mb / s, and writing is 3 Mb / s.
  At the same time, the hard disk can exchange data at a speed of about 30 Mb / s.
• Finally, one more serious drawback, which was already mentioned above, is that flash memory has a limitation on the number of rewriting cycles. The limit ranges from 10,000 to 1,000,000 cycles for different types of microcircuits. And although a million write / erase operations are quite a lot, the presence of a physical limit for the use of a memory chip can be considered a serious drawback of flash devices.
  
  
  

  Toshiba Corporation today announced that its engineers have succeeded in making a breakthrough in new technologies for storing data on hard drives. The company promises to present a new generation in the near future hard drives that will be able to contain much more data.

Vadim Bolotnov, Director of the CROC Solutions Center based on EMC technology.

Today, the issue of accelerating the work of IT services is becoming more and more acute in the face of ever-growing volumes of data. For many applications, the solution is to move storage to flash. The main challenge is to determine for which applications in the data center fast response times are really critical. After moving them to flash drives, applications that remain on "traditional" drives will also experience performance gains.

Hard drive vs flash memory

Modern server is an electronic device with almost no moving mechanical parts. The only exceptions are the hard disk drive (HDD) and cooling fans. Technological limit when transferring information between electronic devices is the speed of light, but on a hard disk, the speed limit is limited by the maximum mechanical speed of the spindle. Therefore, it processes information hundreds and thousands of times slower than processors and memory. While the speed of processors increased tenfold, hard drives evolved much more slowly. Now they are at the same level as at the end of the 20th century. Because of this, many of the applications for which data centers are built are running slower than they could. As a result, expensive, high-load servers are idle while information is being read and written to the hard drive.

Rice. 1. Relative growth in the speed of processors and mechanical hard drives

The relevance of flash memory

The amount of information and the speed of its processing are growing, and our requirements in this regard are also only increasing. Life in the modern world is becoming faster and faster, and not least thanks to technology. We have no desire to waste time waiting using electronic services via the Internet, ATM or standing in line at the supermarket cashier. Low speed the operation of the system that annoys us so much may be a consequence of the slow functioning of the disk subsystem on the central server.

Flash memory can solve the I / O problem, it has a much faster response time. In a lab environment, an optimal hard drive takes an average of 6-7 milliseconds to process a request, while a flash memory takes 0.1 milliseconds. At the same time, it can process tens and hundreds of times more transactions in comparison with a hard disk, which has a limit of 150-200 operations per second.

But this does not mean that the hard drive has "died" and should be discarded. The death of magnetic tape in systems has been predicted for many years. Reserve copy... Flash memory is still more expensive than regular HDD... It is better to use it for a limited range of tasks, because not all applications need high response speed. The cost of flash memory can also vary. There is both an expensive and reliable SLC (Single-level cell) flash memory and a budget MLC (Multi-level cell), but with a shorter service life. One bit of information is written into the SLC cell, two bits are written into the MLC cell. Industrial solutions often use SLC flash memory, while consumer products use the less expensive MLC. But now the trend is changing, and MLC memory is beginning to be used in corporate storage systems.

When deciding on the implementation of a flash drive in a data center, you need to understand whether the company has IT tasks, the prompt implementation of which will allow you to earn more money... For example, there is a report that I would like to run daily, but it is counted as a day, and therefore it is launched weekly. As a result, the forecast of prices in the trading network is made incorrectly, or partners are given not quite up-to-date information, or depositors go to another bank, dissatisfied with the slow operation of ATMs. If there are such tasks, their implementation can almost always be accelerated using flash memory. It is very often thought that the problem is in a poorly written application, but it is possible to actually speed things up with the help of the disk subsystem. It is possible to seriously increase efficiency only due to some technologies, without rewriting the code. The value of flash memory is not in volume, but in speed, and it must be used for suitable applications, counting the cost not in rubles per gigabyte, but in rubles per transaction (IOPS).

When does flash help? Large databases, which are now most often located on high-end disk arrays, can be moved to drives. For example, when SAP users complain about slow work applications, most likely, the problem can be solved by transferring the storage to flash memory. One flash storage system can replace one or more racks in a data center.
Flash memory should also be introduced when a company is running a large workstation virtualization project. Workstation virtualization itself is an interesting and promising technology, with many benefits, from simplifying user support to simplifying data protection. It should be understood that virtualization of workstations implies a heavy load on storage systems. Sometimes adding flash drives to traditional storage systems does not even help here, since controllers may not be able to cope. All-flash storage systems that are optimized for flash do a much better job at this.

Imagine: the work of hundreds and thousands of users who previously interacted only with their hard drives, "Rests on the shoulders" of one storage system. In my practice, I have already come across a situation where the number of virtual machines went to hundreds, the existing storage system ceased to cope. One of the popular technologies that saves storage space when virtualizing workstations is the use of the "golden image". When you need 1000 computers with Windows 7, you don't need to install 1000 distributors and take up several terabytes of operating system files.

The virtualization system will create one so-called "golden" image of the operating system. In this case, all users will read from it, and on their virtual machines only files other than those stored in the "golden image" will be stored. It is clear that a small amount of disk space accounts for great amount read operations. And if the "golden image" somehow seriously changes, then this causes the update of thousands of workstations and creates a very large load on the storage system. While it is tens of times faster, flash memory is much better at this task.

Rice. 2. Comparison of the implementation of VDI on traditional and flash storage systems, using the example of Violin Memory.

Of course, most of the time large companies need to switch to flash, but the switch can be useful for medium-sized companies as well. For example, to efficiently complete a task, it may be sufficient to buy 3-4 flash drives instead of 20-40 hard drives for an important application.

Embedding Flash in Existing Storage Infrastructure

There are several ways to incorporate flash into your existing storage infrastructure. The first and the most a budget option- install flash memory directly in the server - using an SSD flash drive or a PCI Express card containing flash memory chips. This inexpensive way speeding up the server, but it has a number of drawbacks due to which most companies at one time refused to store data on internal drives and left in the direction of the storage system. In particular, this is reduced fault tolerance, complexity in maintenance, insufficient capacity, inability to use flash memory simultaneously for several servers. Flash memory capacity within a single server is limited by the number of PCI-e slots and the performance of the RAID controller, so you can hardly get more than 2TB.

The next two options for implementing flash are related to the most common way of storing data - centralized. The upside is resiliency and the ability to split the resources of this expensive flash memory across multiple tasks. In my practice, I've rarely come across a situation where servers can heavily load such a storage system, even if the customer is large.
One of the ways is associated with vendors of traditional storage systems - IBM, HP, EMC, HDS, who have been making storage systems on conventional hard disks. Since they've been supporting SSDs for several years now, it's a pretty simple way to use flash for those who already have one - you can buy multiple flash drives and insert them into storage shelves. The advantage is simplicity, and the fact that you buy a solution from a trusted vendor.

The downside is that these systems came from the past, they have insufficiently powerful controllers, which contain millions of lines of code, "sharpened" for mechanics. These algorithms are not always suitable for flash memory. It is clear that it is difficult for vendors who have worked with hard drives for many years to switch to flash memory right away, especially since there are many applications that do well on hard drives. Therefore for optimal use SSD can create tiered storage.

The system itself divides the data into those that fast access are needed and those that do not need it or are generally archived. The principle is simple, the system analyzes requests and those data that are requested more often are sent to flash memory, and those that are less often to hard ones SAS drives or SATA. This approach makes optimal use of the still expensive flash drives, but it also has its drawbacks.

One of the main drawbacks is that the system cannot move data in real time and adjust to an unpredictable load profile. The algorithm can only predict, based on statistics, how often one or the other will be requested. Therefore, there is a chance of not guessing which will slow down the application. In addition, flash memory is rapidly becoming cheaper, and perhaps soon such complex algorithms will not be so relevant - for example, it will be possible to put all the data on the MLC flash memory.

The next way The introduction of flash memory is also associated with centralized storage systems. There are a number of new vendors who started development from scratch in the 21st century. Their systems were built specifically for flash memory. They manage the flash memory pool as a whole and minimize the drawbacks - restrictions on the number of rewriting cycles, insufficient write speed compared to reading, etc. One of the most successful examples- Violin Memory, one of the leaders in this market. Several well-known companies have invested in Violin, and one of the most serious investors is Toshiba, which invented NAND memory.

If there is a highly loaded application, then you can simply transfer it entirely to such new system storage, and if it is very large, or it turns out to be too expensive, transfer the most loaded volumes. Specialized storage systems are scalable to tens and hundreds of terabytes of flash memory.

And the last approach is to use not just storage with flash memory, but an attempt to add another layer of cache memory between servers and existing systems storage. Some storage vendors (EMC, NetApp) offer to do this inside their storage systems. A number of young companies are producing stand-alone caching storage systems that fit any storage vendor's. In my opinion, in this case, there are serious risks of compatibility and reliability. If suddenly the slightest failure occurs somewhere, you can lose data, and, accordingly, money, time.

Integration of flash storage and traditional storage systems

There are many tasks that do not need ultra-fast processing speed. Typically, you need to identify applications in the data center that require increased speed disk system, transfer them to flash storage. Remaining on "regular" disk array applications will breathe more freely, and the speed of their work will also increase. Because data grows inexorably, it will never be a problem to occupy the vacant space on the storage system.

Flash memory myths

Many myths about flash memory are associated with the fact that it developed rapidly, almost before our eyes. And for many, the concept of flash memory is associated with the early USB flash drives and SSDs. Indeed, their reliability left much to be desired. This is because flash memory can withstand a limited number of erase-write cycles. SLC - approximately 100,000; MLC - 10,000. This limited number of erase cycles and subsequent writes is cited by opponents of flash memory as the main argument that it worse than harsh disks.

But do not forget that a hard drive is mechanical device, which can also break both mechanical and magnetic components. And the problem of a limited number of rewriting cycles is quite solvable. For flash memory to last for many years or even decades, simply load it evenly. It is impossible that on one site there was only reading, and on the other - constant changes. This task storage controllers can decide. The mechanism responsible for this is called Wear Leveling. So, for the mentioned Violin Memory systems, this algorithm evenly "wears out" the entire storage space as a whole. In other systems, the controller of each SSD is responsible for Wear Leveling, which is slightly less efficient.

Another myth is that flash memory is readable, but not writeable. It has to do with the write handling mechanism. In order to write to a flash memory cell, it must first be cleared. Erasing occurs not with one cell, but with a whole block, in which from 64 to 128 and more cells are combined. And while the erasing process is in progress, all other operations are stopped. If one disk is constantly being written to, it will be busy with the cleaning process in order to write new data. And its performance will indeed be much less than just reading from disk. But the situation changes if the storage system is quite large, for example, several terabytes. Then the controllers can redistribute the load so that this effect of blocking the system before writing will not be strongly affected, and the system will be able to show almost the same performance for writing as for reading.

What's the bottom line?

Flash memory speeds up servers, optimizes data center space, and saves energy. All-flash storage systems today are serious competitors to arrays. top class which are often filled with tens and hundreds of hard drives to give an application desired speed, the capacity is often secondary. In addition to the initial cost of such an array, it takes up quite a lot of space in the data center and requires power and cooling. If a company pays for the lease of a commercial data center, then saving on payments is quite a serious argument.

Since most corporate software - Oracle, SAP, etc. - licensed specifically for cores, you can also save on licenses by optimizing processes and reducing the number of cores involved. If the processors spend less machine time waiting for storage, then they will be able to perform more calculations per unit of time. As a result, we will need fewer cores to solve the same problem.

And one more important point: the lifespan of flash memory is much longer than that of conventional hard drives, and, accordingly, there are less support costs, less risk of data loss if two drives fail at once (to which conventional systems storage).

In terms of the cost of storing information per gigabyte, storage systems on flash memory will be outperformed by systems on HDD for several years, but in terms of the cost of information processing (transaction cost) they are already several times higher than traditional systems. There are many examples in Russian and world practice, when huge storage systems were replaced by small storage systems based on flash memory, which were several times less expensive, but demonstrated amazing application acceleration. I would venture to suggest that in the future, today's 15K and 10K drives will be replaced by SLC and MLC chips.

Flash memory - a kind of solid-state semiconductor non-volatile rewritable memory (EPROM).

All types of flash media existing today can be roughly divided into two classes: flash cards, which include Compact Flash Card, MultiMedia Card and SD Card, and Flash USB Drive (USB Pen Drive). For direct work with flash cards, namely, to read information from them, you need a special device called a card reader, which consists of a controller and a USB connector. The flash module, which is also called a USB flash drive, unlike a flash card, already has a built-in controller and can be connected to a computer via USB.

It can be read as many times as you like (within the data storage period, typically 10-100 years), but you can write to such memory only a limited number of times (the maximum is about a million cycles). Flash memory is widespread and can withstand about 100,000 rewrite cycles - much more than a floppy disk or CD-RW can handle.

Advantages:

No additional energy is required to store data, that is, flash memory is a non-volatile device. Compared to CDs or floppy disks, the energy consumption when working with a flash device is minimal. Therefore, flash memory is very energy efficient. Writing data to a flash-microcircuit requires 10-20 times less energy than similar operations with a CD or floppy disk.

Flash drives have a fairly high recording density, the capacity of modern flash drives is quite large and can significantly exceed the capacity of DVD disks.

Flash-microcircuit allows you to repeatedly (but not indefinitely) overwrite data. That is, flash memory is a rewritable storage device.

At the same time, they work silently. The flash drive does not contain any moving mechanical parts and devices, since it is solid-state memory. And if so, flash devices are resistant to mechanical stress: if there is no mechanics, there is nothing to break.

For example, a flash drive can withstand shocks 10-20 times stronger than a computer hard drive. And not only withstand, but also work in shaking conditions.

Compactness is another advantage of flash-memory drives, which predetermined the use of flash-devices in various small-sized gadgets and “hand-held” devices.

Finally, information recorded on flash memory can be stored for a very long time (about 10, and according to some data, even up to 100 years). That is, a flash microcircuit is a device for long-term data storage.

Due to its compactness, low cost and low power consumption flash memory is widely used in digital portable devices- photo and video cameras, voice recorders, MP3 players, PDAs, mobile phones, as well as smartphones and communicators. In addition, it is used to store firmware in different devices(route isators, mini-automatic telephone exchanges, printers, scanners, modemax), various controllers.

Widespread USB flash drives ("flash drive", USB-drive, USB-disk), which practically supplanted not only floppy disks, but also CDs.

Like other USB devices, flash memory devices do not require separate setting from the BIOS side and is automatically detected in Windows 2003 / XP / Vista.

Such storage devices have excellent development prospects, since there are no mechanical units in their design. Manufacturers are constantly increasing the volume and speed of flash memory chips, and mass production always ultimately leads to significant price reductions.

Flaws:

Flash memory is significantly slower than RAM based on SRAM and DRAM chips. And even in comparison with a hard disk, a flash drive is an outsider. For example, the average speed of reading data from a flash drive is 5 Mb / s, and writing is 3 Mb / s. At the same time, the hard disk can exchange data at a speed of about 30 Mb / s.

Finally, there is one more serious drawback - flash memory has a limitation on the number of rewriting cycles. The limit ranges from 10,000 to 1,000,000 cycles for different types of microcircuits. And although a million write / erase operations are quite a lot, the presence of a physical limit for the use of a memory chip can be considered a serious drawback of flash devices.

Another drawback is sensitivity to electrostatic discharge and radiation, so you need to very carefully follow safety precautions when working with this external medium.

storage medium information disk

In addition, removing the flash drive without stopping the device can also lead to its early damage. Over time, the write speed may decrease, which greatly depends on the bandwidth of the USB port, which is also a disadvantage of flash drives.

Thus, flash drives today have a number of advantages and disadvantages. However, their advantages significantly overlap a few disadvantages, making this product of the computer industry very popular and competitive.

Connection methods peripheral devices to a personal computer

Monitors can be connected via the following VGA interfaces, DVI, HDMI and DisplayPrt. V the given time on the personal computers widely used VGA and DVI interfaces, there are also various adapters, if in the monitor or in motherboard these interfaces are not provided.

Keyboards can be connected via Ps / 2, USB. There are also adapters that allow you to plug a USB keyboard into a PS / 2 port and vice versa.

The connection methods for the mouse are the same as for the keyboard: USB and PS / 2. Currently there are wireless mice... As with USB keyboards mice are detected with the computer turned on.

First of all, they differ in printing technology. There are laser ( led printer), inkjet, matrix and other printers (solid ink, sublimation).

Printers are connected to the computer via USB interface or LPT (older models), as well as using Wi-Fi technology.

Scanners are connected via USB.

MFPs are connected via USB and Ethernet (over the network).
Acoustic speakers... These are devices for playing sound.

They must be connected in two places: to the signal source - a green round connector on the motherboard or discrete sound card; and also to a power source, usually a regular outlet, but there are versions powered by USB.

Distinctive features eSATA and SATA interfaces. Purpose and connection methods.

SATA is a specialized interface. He has found wide application in order to connect a wide variety of information storage devices. For example, using SATA cables, you can connect hard drives, SSD drives and other devices that serve to store information.

The SATA cable is a red ribbon cable that is approximately 1 centimeter wide. This is what he is good at, first of all. Indeed, with such data, it cannot be confused with other interfaces. In particular with ATA (IDE). This interface is also quite applicable in order to connect hard drives. And he did it well, but until the SATA interface came along.

Unlike SATA, ATA is a parallel interface. ATA (IDE) cable consists of 40 wires. Several such wide trains in system unit affected the cooling efficiency. This problem was inherent in the ATA interface, which cannot be said about SATA. It has its advantages. And one of them is the speed of information transfer. Let's say SATA 2.0 can transfer data at 300 MB / s, while SATA 3.0 can transfer as much as 600 MB / s.

Compared to the old ATA (IDE) interface, its advantage is that it has great versatility. With help SATA interface it is possible to connect external devices.

To make it easier to connect external devices, developed special version interface - eSATA (External SATA).

eSATA (External SATA) is an interface for connecting external devices that supports Hot-plug mode. It was created a little later, in the middle of 2004. It has more reliable connectors and a longer cable length. Due to this, the eSATA interface is convenient for connecting various external devices.

A separate cable must be used to power the connected eSATA devices. Today there are bold predictions that in future versions of the interface it will be possible to introduce power directly into the eSATA cable.

ESATA has its own characteristics. The average practical data transfer rate is higher than that of USB 2.0 or IEEE 1394. Signal SATA and eSATA are compatible. However, they require different signal levels.

It also needs two wires to connect: a data bus and a power cable. In the future, it is planned to abandon a separate power cable for external eSATA devices. Its connectors are less fragile. Structurally, they are designed for more connections than SATA. However, they are physically incompatible with regular SATA. Plus shielding of the connector.

The cable length has been increased to two meters. SATA is only 1 meter long. To compensate for the loss compensation, the signal levels were changed in it. The transmission level is increased and the receiver threshold level is lowered.

Features of connection and operation of storage devices with the Serial ATA interface.

SATA(eng. Serial ATA) - serial interface data exchange with information storage devices. SATA is a development of the parallel ATA (IDE) interface, which after the appearance of SATA was renamed PATA (Parallel ATA).

SATA uses a 7-pin connector instead of PATA's 40-pin connector. The SATA cable has a smaller area, due to which the resistance to air blowing over the computer components is reduced, and the wiring inside the system unit is simplified.

SATA cable due to its shape is more resistant to multiple connections. The SATA power cord is also designed with multiple connections... Connector SATA power supply supplies 3 supply voltages: +12 V, +5 V and +3.3 V; but modern devices can operate without voltage +3.3 V, which makes it possible to use a passive adapter from a standard IDE to SATA power connector. A number of SATA devices come with two power connectors: SATA and Molex.

The SATA standard has abandoned the traditional PATA connection of two devices per cable; each device relies on a separate cable, which removes the problem of impossibility simultaneous work devices located on the same cable (and the resulting delays), reduces possible problems during assembly (there is no problem of conflict between Slave / Master devices for SATA), eliminates the possibility of errors when using non-terminated PATA cables.

The SATA standard supports the command queue function (NCQ starting with SATA Revision 1.0a).

Unlike PATA, SATA is hot-swappable active device(used by operating system) (since SATA Revision 1.0)

SATA Revision 1.0 (up to 1.5 Gb / s)

The SATA Revision 1.0 specification was introduced on January 7, 2003. Initially, the SATA standard provided for the operation of the bus at a frequency of 1.5 GHz, providing throughput at approximately 1.2 Gbps (150 MB / s). (The 20% loss in performance is due to the use of the 8b / 10b encoding system, where for every 8 bits useful information there are 2 service bits). SATA / 150 bandwidth is marginally higher than Ultra ATA (UDMA / 133) bus bandwidth. The main advantage of SATA over PATA is the use of a serial bus instead of a parallel one. Despite the fact that the serial exchange method is fundamentally slower than the parallel one, in in this case this is offset by the ability to work for more high frequencies due to the absence of the need for channel synchronization and greater noise immunity of the cable. This is achieved by using a fundamentally different method of data transmission (see LVDS).

SATA Revision 2.0 (up to 3Gb / s)

SATA Specification Revision 2.0 ( SATA II or SATA 2.0, SATA / 300) operates at 3 GHz, provides bandwidth up to 3 Gb / s (300 MB / s for data with 8b / 10b encoding). It was first implemented in the nForce 4 chipset controller by NVIDIA. In theory, SATA / 150 and SATA / 300 devices should be compatible (both a SATA / 300 controller with a SATA / 150 device, and a SATA / 150 controller with a SATA / 300 device) due to the support of speed negotiation (downward), but for some devices and controllers, manual setting of the operating mode is required (for example, on hard drives from Seagate supporting SATA / 300 for forced inclusion a special jumper is provided for the SATA / 150 mode).

SATA Revision 3.0 (up to 6 Gb / s)

SATA Specification Revision 3.0 ( SATA III or SATA 3.0) was introduced in July 2008 and provides a throughput of up to 6 Gb / s (750 MB / s for data with 8b / 10b encoding). Among the improvements of SATA Revision 3.0, compared to the previous version of the specification, in addition to higher speed, we can note improved power management. Also, compatibility is preserved, both at the level of SATA connectors and cables, and at the level of Bob lox exchange protocols.