RAID array (Redundant Array of Independent Disks) - connection of several devices to improve performance and / or reliability of data storage, in translation - a redundant array of independent disks.
According to Moore's Law, the current performance increases every year (namely, the number of transistors on a chip doubles every 2 years). This can be seen in virtually every branch of the computer hardware industry. Processors increase the number of cores and transistors, while decreasing those processes, RAM increases frequency and bandwidth, and solid-state storage memory increases wear resistance and read speed.
But simple hard disk drives (HDDs) have not made much progress in the past 10 years. As was the standard speed of 7200 rpm, so it remained (not taking into account server HDDs with a speed of 10.000 or more). Slow 5400 RPM is still found on laptops. For most users, in order to increase the performance of their computer, it will be more convenient to buy an SDD, but the price for 1 gigabyte of such media is much higher than that of a simple HDD. “How can I improve storage performance without losing too much money and space? How to preserve your data or improve the safety of your data? " There is an answer to these questions - a RAID array.
Types of RAID arrays
Currently, there are the following types of RAID arrays:
RAID 0 or Striped - an array of two or more drives to improve overall performance. The volume of the raid will be total (HDD 1 + HDD 2 \u003d Total volume), the read / write speed will be higher (due to the division of the recording into 2 devices), but the reliability of information safety suffers. If one of the devices fails, then all information in the array will be lost.
RAID 1 or "Mirror" - several disks copying each other to increase reliability. The write speed remains at the same level, the reading speed increases, the reliability increases many times over (even if one device fails, the second will work), but the cost of 1 Gigabyte of information doubles (if you make an array of two hdd).
RAID 2 is an array built around the operation of storage disks and error correction disks. The calculation of the number of HDDs for storing information is performed according to the formula "2 ^ n-n-1", where n is the number of HDD correction. This type is used with a large number of HDDs, the minimum acceptable number is 7, where 4 is for storing information, and 3 is for storing errors. The advantage of this type will be the increased performance compared to a single disk.
RAID 3 - consists of "n-1" disks, where n is the disk for storing parity blocks, the rest are devices for storing information. The information is divided into pieces smaller than the sector size (split into bytes), well suited for working with large files, the speed of reading small files is very low. It is characterized by high performance, but low reliability and narrow specialization.
RAID 4 is similar to type 3, but the division is in blocks, not bytes. This solution managed to fix the low read speed of small files, but the write speed remained low.
RAID 5 and 6 - instead of a separate disk for error correlation, as in previous versions, blocks are used evenly distributed across all devices. In this case, the speed of reading / writing information increases due to parallelization of the recording. The disadvantage of this type is long-term data recovery in case of failure of one of the disks. During recovery, there is a very high load on other devices, which reduces reliability and increases the failure of another device and the loss of all data in the array. Type 6 improves overall reliability but decreases performance.
Combined types of RAID arrays:
RAID 01 (0 + 1) - Two Raid 0's are combined into Raid 1.
RAID 10 (1 + 0) - RAID 1 disk arrays that are used in Type 0 architecture. It is considered the most reliable storage option, combining high reliability and performance.
You can also create an array from SSD drives... According to 3DNews testing, such a combination does not give a significant increase. Better to buy a drive with a higher performance PCI or eSATA interface
Raid array: how to create
Created by connecting through a special RAID controller. At the moment there are 3 types of controllers:
- Software - the array is emulated by software, all calculations are performed by the CPU.
- Integrated - mostly common on motherboards (not in the server segment). A small chip on the mat. the board responsible for emulating the array, calculations are performed through the CPU.
- Hardware - an expansion card (for stationary computers), usually with a PCI interface, has its own memory and a computing processor.
RAID array hdd: How to make 2 disks via IRST
Data recovery
Some data recovery options:
- In the event of a Raid 0 or 5 failure, the RAID Reconstructor utility can help, which will collect the available information of the drives and overwrite it to another device or medium as an image of the previous array. This option will help if the disks are working properly and there is a software error.
- For Linux systems, mdadm recovery (utility for managing software RAID arrays) is used.
- Hardware recovery should be performed through specialized services, because without knowledge of the controller's operating methodology, you can lose all data and it will be very difficult or impossible to return them.
There are many nuances to consider when creating a Raid on your computer. Basically, most of the options are used in the server segment, where stability and data safety are important and necessary. If you have any questions or additions, you can leave them in the comments.
Have a great day!
At the end of last week I bought components for a computer and ran into a number of problems while setting up the equipment. The new computer was designed to store databases in the office of one company, therefore a RAID array was needed. The budget was about 20,000 rubles, so I collected it on the AMD platform. ASUS M4A88TD-M motherboard and two identical WD 500 Gb hard drives. To configure the RAID array, the HDD is connected to the SATA0 and SATA1 connectors. Created a RAID 1 array, combining hard drives with increased reliability and fault tolerance. When hard drives mirror each other. The recommendations described below are suitable for configuring RAID0, increasing the speed of disks.
First, I went into the BIOS. For my motherboard, pressing the DEL button while booting, for third-party boards may be F2. In the configuration settings SATA switched the IDE mode to RAID. Hit F10 to save the settings and reboot the computer.
Second, you need to include the RAID array. This is the first moment at which I fell into a stupor. The instructions for the ASUS motherboard do not say a word about this. While booting the computer, I pressed Ctrl + F. Opened the Option ROM Utility menu. Here I selected the second item by pressing 2.
In this menu, pressed Ctrl + C to create a RAID. Going through the points, I turned on the RAID Mode functions in the RAID1 position, opposite the Y disks. Then I pressed Ctrl + Y twice, entered the name of the RAID array and saved the set parameters. Quit and rebooted the computer.
Now, when you boot the computer, you can see that the system has a RAID1 array connected.
Third, I determined the priority of the download queue from different devices. To do this, I had to enter the BIOS again. The DVD drive, followed by my RAID, and the last connected device, i.e. flash drives.
I installed Windows 7 on a RAID array. In principle, further advice is suitable for installing Windows XP, Vista, Server 2008 and Windows 8 on a RAID array. Before starting the installation, I went from another computer to the ASUS website and downloaded the AMD RAID driver. The RAID driver has been loaded onto a flash drive, it does not need to be inserted into the USB connector until the hard drive partitions are selected. The Windows image was on DVD. After that, I went on to install the OS.
Fourth, I used the driver from the flash drive when I came to the partition selection. I inserted a USB flash drive, clicked Download and Browse.
In the pop-up menu, I chose the driver directory, operating system and bit depth. In my case Windows 7 64bit.
Windows Installer has detected AMD AHCI Compatible RAID Controller driver. It was enough to see the hard drive partition. I took out the flash drive from the USB port.
Here the second problem awaited me, when Windows 7 was not installed. I chose the standard Create method, the installer defined the entire disk volume as Primary. Clicked Next and got an error. The installer was unable to create a new or find an existing system partition. Additional information and so on. When Windosw won't install due to a partition, the solution is to partition the disk yourself. Deleted all sections. Pressed Shift + F10.
Fifth, pressing Shift + F10, brought up the command line. Shift + Alt returns the English keyboard layout on the Russian distribution. Entered diskpart, the command to call the disk utility. The following command is list disk. I saw two disks in the system: disk 0 - USB flash drive, disk 1 - RAID array. I selected disk 1 with the select disk 1 command. Then I entered create partition primary size \u003d 131072, created a system partition with a size of 128 GB. The create partition primary command is responsible for this. Size command to determine the size of the disk.
The second part of the disk was defined in the partition with the create partition extended command. Didn't use size to include all remaining space in the second drive. That in the future will allow you to create a Logical Disk.
I selected the first partition with the select partition 1 command. The active command marked the partition as active. After that, I closed the command prompt window. I pressed the Update button.
After updating the list of partitions, I saw two disks with a volume of 128 GB and 337 GB. I selected the first section and clicked Next.
Warmly awaited inscription Installing Windows ... Windows was installed as usual.
I did it several times in three evenings. Some attempts were made with errors, which increased the time. If you have any questions, write in the comments. For example, you need to restart your computer after partitioning the disk into new partitions if the flash drive was inserted before installing Windows. All of the above was repeated at a time to ensure the correctness of the five-point algorithm. Installing Windows 7 on RAID works, tested!
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Greetings to blog readers!
Today there will be another article on a computer topic, and it will be devoted to such a concept as a Raid array of disks - I am sure that this concept will say absolutely nothing to many, and those who have already heard about it somewhere have no idea what it is. in general such. Let's figure it out together!
What is Raid Array?
Without going into details of terminology, a Raid array is a kind of complex built of several hard drives, which allows you to more competently distribute functions between them. How do we usually place hard drives on a computer? We connect one hard drive to Sata, then another, then a third. And drives D, E, F and so on appear in our operating system. We can put some files on them or install Windows, but in fact they will be separate disks - removing one of them we will not notice anything at all (if the OS was not installed on it) except that we will not be able to access the ones written on them files. But there is another way - to combine these disks into a system, to set them a certain algorithm of joint work, as a result of which the reliability of information storage or the speed of their operation will significantly increase.
But before we can create this system, we need to know if the motherboard supports Raid disk arrays. Many modern motherboards already have a built-in Raid controller, which allows you to combine hard drives. See the motherboard descriptions for supported array designs. For example, let's take the first ASRock P45R2000-WiFi board that I came across in Yandex Market.
Here, a description of the supported Raid arrays is displayed in the Sata Disk Controllers section.
In this example, we see that the Sata controller supports the creation of Raid arrays: 0, 1, 5, 10. What do these numbers mean? This is a designation of various types of arrays, in which disks interact with each other according to different schemes, which are designed, as I said, either to speed up their work, or to increase reliability from data loss.
If the computer's motherboard does not support Raid, then you can purchase a separate Raid controller in the form of a PCI card, which is inserted into a PCI slot on the motherboard and allows it to create arrays from disks. For the controller to work, after installing it, you will also need to install the raid driver, which either comes on the disk with this model, or you can simply download it from the Internet. It is best not to save money on this device and buy from some well-known manufacturer, for example Asus, and with Intel chipsets.
I suspect that you still do not really have an idea of \u200b\u200bwhat it is all about, so let's take a closer look at each of the most popular types of Raid arrays to make everything clearer.
RAID 1 array
Raid 1 array is one of the most common and budget options that uses 2 hard drives. This array is designed to provide maximum protection for user data, because all files will be simultaneously copied to 2 hard drives at once. In order to create it, we take two hard drives of the same size, for example, 500 GB each and make the appropriate settings in the BIOS to create an array. After that, your system will see one hard drive not 1 TB in size, but 500 GB, although two hard drives are physically working - the calculation formula is given below. And all files will be simultaneously written to two disks, that is, the second will be a full backup of the first. As you understand, if one of the disks fails, you will not lose any part of your information, since you will have a second copy of this disk.
Also, the operating system will not notice the breakdown, which will continue to work with the second disk - only a special program that monitors the operation of the array will notify you of the problem. You just need to remove the faulty disk and connect the same one, only the working one - the system will automatically copy all data from the remaining healthy disk to it and continue working.
The disk space that the system will see is calculated here using the formula:
V \u003d 1 x Vmin, where V is the total and Vmin is the memory size of the smallest hard drive.
RAID 0 array
Another popular scheme, which is designed to increase not the reliability of storage, but, on the contrary, the speed of work. It also consists of two HDDs, however, in this case, the OS already sees the total total volume of the two disks, i.e. If you combine 500 GB disks in Raid 0, the system will see one 1 TB disk. The speed of reading and writing is increased due to the fact that blocks of files are written alternately on two disks - but at the same time the fault tolerance of this system is minimal - if one of the disks fails, almost all files will be damaged and you will lose part of the data - the one that was written on broken disk. After that, you will have to restore information at the service center.
The formula for calculating the total disk space visible to Windows looks like this:
If, before reading this article, by and large, you were not worried about the fault tolerance of your system, but would like to increase the speed of work, then you can buy an additional hard drive and safely use this type. By and large, at home the overwhelming majority of users do not store any super-important information, and you can copy some important files to a separate external hard drive.
Raid 10 array (0 + 1)
As the name implies, this type of array combines the properties of the two previous ones - it is like two Raid 0 arrays combined into Raid 1. Four hard drives are used, on two of them information is written in blocks alternately, as it was in Raid 0 , and on the other two, full copies of the first two are created. The system is very reliable and at the same time quite fast, but very expensive to organize. To create, you need 4 HDDs, while the system will see the total volume according to the formula:
That is, if we take 4 disks of 500 GB each, then the system will see 1 disk of 1 TB.
This type, as well as the next, is most often used in organizations, on server computers, where it is necessary to ensure both high speed of work and maximum security against loss of information in case of unforeseen circumstances.
RAID 5 array
The Raid 5 array is the optimal combination of price, speed and reliability. In this array, at least 3 HDDs can be used, the volume is calculated from a more complex formula:
V \u003d N x Vmin - 1 x Vmin, where N is the number of hard drives.
So, let's say we have 3 500 GB disks. The volume visible to the OS will be 1 TB.
The array works as follows: blocks of split files are written to the first two disks (or three, depending on their number), and the checksum of the first two (or three) files is written to the third (or fourth). Thus, if one of the disks fails, its contents can be easily recovered due to the checksum on the last disk. The performance of such an array is lower than that of Raid 0, but as reliable as Raid 1 or Raid 10, and at the same time cheaper than the latter. you can save on the fourth hard.
The diagram below shows a Raid 5 diagram of four HDDs.
There are also other modes - Raid 2,3, 4, 6, 30, etc., but they are largely derived from those listed above.
How to Install Raid Disk Array on Windows?
I hope we figured out the theory. Now let's look at the practice - I think it won't be difficult for experienced PC users to insert a controller into the PCI Raid slot and install drivers.
How can you create an array of connected hard drives in the Windows Raid operating system now?
It is best, of course, to do this when you have just purchased and connected clean hard drives without an installed OS. First, we restart the computer and go into the BIOS settings - here you need to find the SATA controllers to which our hard drives are connected and set them to RAID mode.
After that we save the settings and reboot the PC. On a black screen, information will appear that you have Raid mode turned on and about the key with which you can get into its settings. In the example below, it is suggested to press the “TAB” key.
It may be different depending on the Raid controller model. For example, "CNTRL + F"
We go into the settings utility and click something like “Create array” or “Create Raid” in the menu - the labels may differ. Also, if the controller supports several types of Raid, then you will be prompted to choose which one you want to create. In my example, only Raid 0 is available.
After that, we go back to the BIOS and in the boot order setting we see not several separate disks, but one in the form of an array.
That's all - RAID is configured and now the computer will treat your disks as one. This is how, for example, Raid will be visible when installing Windows.
I think you have already understood the benefits of using Raid. Finally, I will give a comparative table of measurements of the speed of writing and reading a disk separately or as part of Raid modes - the result, as they say, is obvious.
Sergey Pakhomov
All modern motherboards are equipped with an integrated RAID controller, and top models even have several integrated RAID controllers. Whether integrated RAID controllers are in demand by home users is a separate question. In any case, a modern motherboard provides the user with the ability to create a RAID array from several disks. However, not every home user knows how to create a RAID array, which level of the array to choose, and generally has a poor idea of \u200b\u200bthe pros and cons of using RAID arrays.
History of creation
The term "RAID array" first appeared in 1987, when American researchers Patterson, Gibson and Katz from the University of California, Berkeley, in their article "A Case for Redundant Arrays of Inexpensive Discs, RAID", described how In this way, multiple low-cost hard drives can be combined into a single logical device so that the result is increased system capacity and performance, and the failure of individual drives does not lead to failure of the entire system.
More than 20 years have passed since the publication of this article, but the technology of building RAID arrays has not lost its relevance today. The only thing that has changed since then is the decoding of the RAID acronym. The fact is that initially RAID arrays were not built on cheap disks, so the word Inexpensive was changed to Independent, which was more in line with reality.
Operating principle
So, RAID is a redundant array of independent disks (Redundant Arrays of Independent Discs), which is entrusted with the task of providing fault tolerance and improving performance. Fault tolerance is achieved through redundancy. That is, a part of the disk space is allocated for service purposes, becoming inaccessible to the user.
The increase in the performance of the disk subsystem is provided by the simultaneous operation of several disks, and in this sense, the more disks in the array (up to a certain limit), the better.
Disk drives in an array can be shared using either parallel or independent access. With parallel access, disk space is divided into blocks (strips) for data recording. Likewise, the information to be written to the disk is divided into the same blocks. When writing, separate blocks are written to different disks, and several blocks are written to different disks simultaneously, which leads to an increase in performance in write operations. The necessary information is also read in separate blocks simultaneously from several disks, which also contributes to an increase in performance in proportion to the number of disks in the array.
It should be noted that the parallel access model is implemented only if the size of the data write request is larger than the size of the block itself. Otherwise, it is almost impossible to write multiple blocks in parallel. Imagine a situation where the size of an individual block is 8KB, and the size of a write request is 64KB. In this case, the original information is cut into eight blocks of 8 KB each. If you have a four-disk array, you can write four blocks, or 32 KB, at a time. Obviously, in this example, the write speed and read speed will be four times higher than when using a single disc. This is only true for an ideal situation, but the request size is not always a multiple of the block size and the number of disks in the array.
If the size of the data being written is less than the block size, then a fundamentally different model is implemented - independent access. Moreover, this model can also be used when the size of the recorded data is greater than the size of one block. With independent access, all the data of a single request is written to a separate disk, that is, the situation is identical to working with one disk. The advantage of the independent access model is that if multiple write (read) requests are received at the same time, they will all be executed on separate disks independently of each other. This situation is typical, for example, for servers.
According to different types of access, there are also different types of RAID arrays, which are usually characterized by RAID levels. In addition to the type of access, RAID levels differ in the way they are located and redundant information is generated. Redundant information can either be placed on a dedicated disk or shared across all disks. There are many ways to generate this information. The simplest of these is full duplication (100 percent redundancy), or mirroring. In addition, error correction codes are used as well as parity computation.
RAID levels
Currently, there are several RAID levels that can be considered standardized - these are RAID 0, RAID 1, RAID 2, RAID 3, RAID 4, RAID 5 and RAID 6.
Various combinations of RAID levels are also used to combine their merits. This is usually a combination of some fault tolerant level and level 0 used to improve performance (RAID 1 + 0, RAID 0 + 1, RAID 50).
Note that all modern RAID controllers support the JBOD (Just a Bench Of Disks) function, which is not intended for creating arrays - it provides the ability to connect individual disks to the RAID controller.
It should be noted that the RAID controllers integrated on motherboards for home PCs do not support all RAID levels. Dual-port RAID controllers support only levels 0 and 1, while RAID controllers with a large number of ports (for example, the 6-port RAID controller integrated into the south bridge of the ICH9R / ICH10R chipset) also support levels 10 and 5.
In addition, if we talk about motherboards based on Intel chipsets, then they also implement the Intel Matrix RAID function, which allows you to create RAID matrices of several levels on several hard drives at the same time, allocating a part of the disk space for each of them.
RAID 0
RAID level 0, strictly speaking, is not a redundant array and therefore does not provide data storage reliability. Nevertheless, this level is actively used in cases where it is necessary to ensure high performance of the disk subsystem. When creating a RAID 0 array, information is split into blocks (sometimes these blocks are called stripes), which are written to separate disks, that is, a system with parallel access is created (if, of course, the block size allows it). With the ability to concurrent I / O from multiple drives, RAID 0 provides the fastest data transfer rate and maximum disk space efficiency, since it does not require storage space for checksums. The implementation of this level is very simple. RAID 0 is mainly used in areas where fast transfer of large amounts of data is required.
RAID 1 (Mirrored disk)
RAID Level 1 is a 100 percent redundant array of two drives. That is, the data is simply completely duplicated (mirrored), due to which a very high level of reliability (as well as cost) is achieved. Note that implementing Level 1 does not require pre-partitioning disks and data into blocks. In the simplest case, two drives contain the same information and are one logical drive. If one disk fails, its functions are performed by another (which is absolutely transparent to the user). The array is restored by simple copying. In addition, this level doubles the speed of information reading, since this operation can be performed simultaneously from two disks. This information storage scheme is used mainly in cases where the cost of data security is much higher than the cost of implementing the storage system.
RAID 5
RAID 5 is a fault-tolerant disk array with distributed checksum storage. When writing, the data stream is divided into blocks (stripes) at the byte level and simultaneously written to all disks in the array in a circular order.
Suppose the array contains n disks, and the stripe size d... For each portion of n-1 stripes checksum is calculated p.
Stripe d1 written to the first disk, stripe d2 - on the second and so on up to the stripe dn-1which is written to ( n-1) th drive. Further on n-th disk checksum is written pn, and the process is cyclically repeated from the first disk on which the stripe is written dn.
Recording process (n-1) stripes and their checksum are produced simultaneously for all n disks.
The checksum is calculated using a bitwise exclusive OR (XOR) operation on the data blocks being written. So, if there is n hard drives, d - data block (stripe), the checksum is calculated using the following formula:
pn \u003d d1+d2+ ... + d1-1.
If any disk fails, the data on it can be recovered from the control data and from the data remaining on the healthy disks.
As an illustration, consider blocks of four bits. Suppose there are only five drives for storing data and writing checksums. If there is a sequence of bits 1101 0011 1100 1011, divided into blocks of four bits, then to calculate the checksum, you must perform the following bitwise operation:
1101 + 0011 + 1100 + 1011 = 1001.
Thus, the checksum written to the fifth disc is 1001.
If one of the disks, for example, the fourth one, fails, then the block d4 \u003d 1100 will be unavailable when read. However, its value can be easily restored from the checksum and from the values \u200b\u200bof other blocks using the same "exclusive OR" operation:
d4 \u003d d1+d2+d4+p5.
In our example, we get:
d4 \u003d (1101) + (0011) + (1100) + (1011) = 1001.
In the case of RAID 5, all the disks in the array are the same size, but the total capacity of the disk subsystem available for writing becomes less than exactly one disk. For example, if five disks are 100 GB, then the actual size of the array is 400 GB because 100 GB is reserved for audit information.
RAID 5 can be built on three or more hard drives. As the number of hard drives in an array increases, its redundancy decreases.
RAID 5 has an independent access architecture that allows multiple reads or writes to be performed simultaneously
RAID 10
RAID 10 is a combination of levels 0 and 1. A minimum of four drives are required for this level. In a RAID 10 array of four disks, they are paired together into arrays of level 0, and both of these arrays are combined as logical disks into an array of level 1. Another approach is also possible: initially, the disks are combined into mirrored arrays of level 1, and then logical disks based on these arrays - to an array of level 0.
Intel Matrix RAID
The considered RAID arrays of levels 5 and 1 are rarely used at home, which is primarily due to the high cost of such solutions. The most commonly used for home PCs is a level 0 array on two disks. As we have already noted, RAID level 0 does not provide data storage security, and therefore end users are faced with a choice: to create a fast, but not reliable data storage, RAID level 0, or, doubling the cost of disk space, - RAID- a Tier 1 array that provides data reliability without significant performance gains.
To address this difficult problem, Intel has developed Intel Matrix Storage Technology, which combines the benefits of Tier 0 and Tier 1 arrays on just two physical disks. And in order to emphasize that in this case we are talking not just about a RAID array, but about an array that combines both physical and logical disks, the technology name uses the word "matrix" instead of the word "array".
So what is a dual-drive RAID array with Intel Matrix Storage Technology? The basic idea is that if there are several hard drives in the system and a motherboard with an Intel chipset that supports Intel Matrix Storage technology, it is possible to divide the disk space into several parts, each of which will function as a separate RAID array.
Let's take a look at a simple example of a RAID matrix consisting of two 120 GB drives. Any of the disks can be split into two logical disks, for example, 40 GB and 80 GB. Then two logical disks of the same size (for example, 40 GB) can be combined into a RAID level 1, and the remaining logical disks - into a RAID level 0.
In principle, using two physical disks, you can also create only one or two RAID-0 matrices, but it is impossible to get only matrices of level 1. That is, if the system has only two disks, then Intel Matrix Storage technology allows you to create the following types of RAID matrices:
- one matrix of level 0;
- two matrices of level 0;
- level 0 matrix and level 1 matrix.
If the system has three hard drives, then the following types of RAID matrices can be created:
- one matrix of level 0;
- one level 5 matrix;
- two matrices of level 0;
- two matrices of level 5;
- level 0 matrix and level 5 matrix.
If the system has four hard drives, then it is additionally possible to create a RAID 10 matrix, as well as combinations of level 10 and level 0 or 5.
The article presents the general structure and organization of RAID systems. The necessary theoretical part is briefly considered, after which the practical points are shown directly. Anyone who does not know what a hard drive is - can read the article. to create a Raid array, you need a couple of hard drives.
The value of information as such only increases over time, while the cost of the methods that determine its reliable storage regularly decreases. For example, motherboards equipped with the ability to create RAID arrays ten years ago "bite" the price, but today almost all motherboards on the iP55 chipset (which is just a pre-top set of system logic) are equipped with chipset support for RAID systems.
RAID arrays, by the way, due to their excellent price-quality ratio, today are one of the most popular ways to securely organize data. If we translate the abbreviation RAID from English, it is a redundant array consisting of independent disks. Due to the low fault tolerance of a separate hard disk, a concept was developed that allows you to combine hard drives into one array. The management of this array was entrusted to a separate controller (today it can be directly a microcircuit on a board, or software tools that use CPU resources). RAID systems are initially focused on fault tolerance (except for RAID level 0), therefore, theoretically, if one of the HDDs breaks down, the information as a whole, written on the volume, remains available, at least for reading.
There is a fairly extensive gradation of RAID levels (ways of organizing data in an array), in order to create a RAID system, you must have at least a basic understanding of its principles of operation, in fact this is a topic for a separate article, we will limit ourselves to only brief sketches of the most relevant ones.
RAID0.
Data is written one by one to different drives (stripes), thanks to this, as a result, we can get an almost double increase in linear read speed. There is no fault tolerance, in case of failure of at least one hard disk, all the data in the array is lost. It is used, as a rule, for quick work with information that can be donated in case of something, for example, for temporary folders of Adobe Fotoshop ... Some people use this for the OS (gamers, enthusiasts, etc.).
Mirroring. It's simple. More hard drives - the higher the cost of the useful volume, but the higher the fault tolerance. In its classic version, there is no performance gain. Modifications of the RAID 1e type are off-budget, so we will skip the consideration of them.
Levels 2,3,4 have practically lost their former popularity. Today, the most relevant RAID array that combines performance and fault tolerance is RAID 5. As in the case of RAID 0, data is written to different drives (also stripes) one by one, but supplemented with checksums. As a result, the usable capacity of a RAID 5 consisting of n disks is equal to n-1 disks. In case of failure of one hard drive, the information remains available, in case of failure of two or more, it is lost.
RAID10 (or RAID 1 + 0).
The most popular representative of composite RAID systems. In order to somehow speed up the work of a classic mirror, the idea arose of combining them into a fast array. It is a merging of mirrors (RAID 1) into one large stripe (RAID 0). The main disadvantage is the higher cost of the useful volume, the advantages are higher data processing speed, in addition, increased fault tolerance. Theoretically, two drives can fail simultaneously, but from different subarrays.
As I wrote above, a controller is needed to organize RAID systems. There are software and hardware controllers (hardware).
Consider the hardware.
As in the case of video cards, this area is also divided into integrated (into the motherboard) and discrete. Integrated ones can be divided into chipset (implementation via the "south bridge") and controllers made by third-party developers (an additional non-chipset microcircuit is soldered on the motherboard). The latter are most often extremely primitive; as a rule, only RAID levels 0 and 1 are supported.
Chipset variations are more interesting and can compete with a number of discrete counterparts in their functionality. For example, the latest chipsets from Intel allow for RAID 0,1,5,10 levels.
Discrete solutions for organizing RAID arrays, again, like video cards, are expensive and cheap (budget). They differ, of course, by the available functionality, reliability, and also by means of "rebuild" (internal restructuring - self-healing).
In the photo 1,2,3
representatives of the Low-end, Middle-end and High-end sectors.
It should be noted that a number of budget discrete variations, as well as all integrated solutions, are very often called software solutions because of the greater requirements for CPU resources, compared to expensive counterparts. A powerful (own) processor of an expensive discrete RAID controller almost completely independently serves the array, while the Low-end class, in view of its weak capabilities and very often primitiveness, increasingly appeals to the capabilities of the CPU, thereby additionally loading the system.
But if integrated versions have at least some basic microcircuit, from the functionality of which you can push off, then pure software solutions do not have this at all.
Software solutions.
Everything is very simple here, a RAID array is created using OS tools. In view of greater reliability, as a rule, server variations of operating systems are used. For OS, RAID is seen just like a regular hardware counterpart. The main advantage of this kind of solutions is the cost: there is no need to buy an expensive controller. There is, of course, a minus, sometimes completely negating the above-described plus - it's low reliability. If suddenly something happens to the OS (viruses start, for example), then you can lose all data together with the blue screen. Therefore, if anyone else organizes such solutions for work so far, then only level 0 (for OS, or for fast buffers) or 1. "Building" software RAID is carried out by means of the built-in partition manager.
(photo 4, 5)
Now let's look directly at the installation of a hardware RAID array.
The first case. If we have any solution integrated into the motherboard, then we need to use it. This is done through the motherboard BIOS, as a rule, by simply moving it to the "Enable" position.
(photo 6)
The second case. If we have a discrete RAID, then we simply insert the card and connect the hard drives to it.
As in the first and second options, after turning on the computer and passing it through the "POST-table", the machine should see the controller and offer to press any key combination to enter the BIOS, but already the controller. It will be something like Ctrl + A, Ctrl + g, etc. Clicked - entered.
(photo 7)
If we use expensive RAID, then the BIOS will differ dramatically.
(photo 8)
You can even use a mouse here.
All interfaces are intuitive, the only thing that can be confusing is the English language. The general principle is as follows: select the required hards and initialize them to the RAID level you need.
(photo 9)
After creation, you can start installing the OS (if required), for details on this process, see the article on installing XP on a laptop, the principle is the same. The only difference that is relevant for Windows Vista and similar operating systems is the ability to use a flash drive, i.e. The necessary drivers for the controller can be copied to a USB-drive, and then during installation, simply specify the path, or integrate these drivers directly into the distribution kit via vLite (www.vlite.net).
RAID solutions are smoothly moving from the category of elite to the section "for everyone", thereby becoming an increasingly affordable tool for reliable data handling. When upgrading your computer and choosing a motherboard, you should pay attention to the availability of support for this RAID. Perhaps it will someday save your "those pictures" ...
