Creating a Raid Disk Array on Windows. What is a raid array - types and settings

And so on, so on, so on, so on. So, today we’ll talk about RAID arrays based on them.

As you know, these same hard drives They also have a certain safety margin after which they fail, as well as characteristics that affect performance.

As a result, probably many of you, one way or another, have once heard about certain raid arrays that can be made from ordinary hard drives in order to speed up the operation of these same disks and the computer as a whole or to ensure increased reliability of data storage.

Surely you also know (and if you don’t know, it doesn’t matter) that these arrays have different sequence numbers ( 0, 1, 2, 3, 4 etc.), and also perform quite well various functions. This phenomenon actually takes place in nature and, as you have already guessed, it is precisely these same RAID arrays is what I want to tell you in this article. More precisely, I’m already telling you ;)

Let's go.

What is RAID and why is it needed?

RAID- this is a disk array (i.e. a complex or, if you like, a bundle) of several devices - hard drives. As I said above, this array serves to increase the reliability of data storage and/or to increase the speed of reading/writing information (or both).

Actually, what exactly this bunch of disks does, i.e. speeding up work or increasing data security, depends on you, or more precisely, on the choice of the current configuration of the raid(s). Different types these configurations are precisely what are noted different numbers: 1, 2, 3, 4 and, accordingly, perform different functions.

Simply, for example, in the case of constructing 0 -th version (description of variations 0, 1, 2, 3 etc. - read below) You will get a noticeable increase in productivity. And in general hard drive Nowadays there is just a narrow channel in the speed of the system.

Why did this happen in general?

Hard drives only grow in volume due to the rotation speed of their heads (with the exception of rare models like Raptor"ov) has been frozen for quite some time at around 7200 , the cache isn’t exactly growing either, the architecture remains almost the same.

In general, in terms of performance, disks are stagnant (the situation can only be saved by developing ones), but they play a significant role in the operation of the system and, in some places, full-fledged applications.

In the case of constructing a single unit (in the sense of number 1 ) raid, you will lose a little in performance, but you will receive some tangible guarantee of the security of your data, because it will be completely duplicated and, in fact, even if one disk fails, everything will be located entirely on the second without any loss.

In general, I repeat, raids will be useful to everyone. I would even say that they are required :)

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What is RAID in the physical sense?

Physically RAID-array represents from two to n-number of connected hard drives supporting the ability to create RAID(or to the corresponding controller, which is less common because these are expensive for the average user (controllers are usually used on servers due to their increased reliability and performance)), i.e. To the eye, nothing changes inside the system unit; there are simply no unnecessary connections or connections of disks to each other or to anything else.

In general, everything in the hardware is almost the same as always, and only the software approach changes, which, in fact, sets, by selecting the type of raid, exactly how the connected disks should work.

Programmatically, in the system, after creating a raid, no special quirks appear either. In fact, the whole difference in working with a raid lies only in a small setting that actually organizes the raid (see below) and in the use of the driver. Otherwise, EVERYTHING is absolutely the same - in "My Computer" the same C, D and other disks, all the same folders, files... In general and in software, by eye, they are completely identical.

Installing the array is not difficult: we just take a motherboard that supports the technology RAID, we take two completely identical ones, - this is important!, - both according to the characteristics (size, cache, interface, etc.) and according to the manufacturer and model of the disk and connect them to this motherboard. Next, just turn on the computer, go to BIOS and set the parameter SATA Configuration: RAID.

After this, during the computer boot process (usually before booting Windows) a panel appears displaying information about the disk in the raid and outside it, where you actually need to click CTR-I to configure the raid (add disks to it, delete, etc., etc.). Actually, that's all. Then there are other joys of life, that is, again, everything is as always.

Important note to remember

When creating or deleting a raid ( 1 This doesn’t seem to apply to the th raid, but it’s not a fact) all information is inevitably deleted from the disks, and therefore it’s clearly not worth just conducting an experiment, creating and deleting various configurations. Therefore, before creating a raid, first save all necessary information(if it exists), and then experiment.

As for the configurations.. As I already said, RAID There are several types of arrays (at least from the main basis - this is RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, RAID 6). To begin with, I will talk about two that are the most understandable and popular among ordinary users:

• RAID 0- disk array to increase recording speed.
• RAID 1- mirrored disk array.

And at the end of the article I’ll quickly go over the others.

RAID 0 - what is it and what is it used for?

So.. RAID 0(aka, striping) - uses two to four (more, less often) hard drives that jointly process information, which increases productivity. To make it clear, carrying bags for one person takes longer and is more difficult than for four people (although the bags remain the same in their physical properties, only the powers interacting with them change). Programmatically, information on a raid of this type is divided into data blocks and written to both/several disks in turn.

One block of data on one disk, another block of data on another, and so on. This significantly increases performance (the number of disks determines the multiplicity of the increase in performance, i.e. 4 disks will run faster than two), but the security of data on the entire array suffers. If any of the components included in such RAID hard drives (i.e. hard drives), all information is almost completely and irretrievably lost.

Why? The fact is that each file consists of a certain number of bytes... each of which carries information. But in RAID 0 In an array, the bytes of one file can be located on several disks. Accordingly, if one of the disks “dies,” an arbitrary number of bytes of the file will be lost and it will simply be impossible to recover it. But there is more than one file.

In general, when using such a raid array, it is strongly recommended to make permanent valuable information on external media. The raid really provides noticeable speed - I’m telling you this in own experience, because such happiness has been installed in my home for years.

RAID 1 - what is it and what is it used for?

What about RAID 1?(Mirroring - “mirror”). Actually, I’ll start with the drawback. Unlike RAID 0 it turns out that you seem to be “losing” volume second hard disk (it is used to write to it a complete (byte for byte) copy of the first hard drive while RAID 0 this space is completely accessible).

The advantage, as you already understood, is that it has high reliability, i.e. everything works (and all data exists in nature, and does not disappear when one of the devices fails) as long as at least one disk is functioning , i.e. Even if you roughly destroy one disk, you will not lose a single byte of information, because the second is a pure copy of the first and replaces it when it fails. This type of raid is often used on servers due to the incredible viability of data, which is important.

With this approach, performance is sacrificed and, according to personal feelings, it is even less than when using one disk without any raids. However, for some, reliability is much more important than performance.

RAID 2, 3, 4, 5, 6 - what are they and what are they used with?

The description of these arrays is here as much as possible, i.e. purely for reference, and even then in a compressed form (in fact, only the second is described). Why is this so? At least due to the low popularity of these arrays among the average (and, in general, any other) user and, as a consequence, my little experience in using them.

RAID 2 reserved for arrays that use some kind of Hamming code (I wasn’t interested in what it was, so I won’t tell you). The principle of operation is approximately this: data is recorded on the corresponding devices in the same way as in RAID 0, that is, they are divided into small blocks across all disks that are involved in storing information.

The remaining (specially allocated for it) disks store error correction codes, which can be used to restore information in the event of a hard drive failure. So in arrays of this type, disks are divided into two groups - for data and for error correction codes

For example, you have two disks that provide space for the system and files, and two more will be completely dedicated to correction data in case the first two disks fail. In essence, this is something like a zero raid, only with the ability to at least somehow save information in the event of failure of one of the hard drives. Rarely expensive - four disks instead of two with a very controversial increase in security.

RAID 3, 4, 5, 6.. About them, no matter how strange it may sound on the pages of this site, try reading about them on Wikipedia. The fact is that in my life I have encountered these arrays extremely rarely (except that the fifth one came to hand more often than others) and I cannot describe in accessible words the principles of their operation, and I absolutely do not want to reprint the article from the above proposed resource, at least due to the presence of infuriating formulations in these, which even I can barely understand.

Which RAID should you choose?

If you play games, often copy music, movies, install resource-intensive programs, then you will definitely find it useful RAID 0. But be careful when choosing hard drives - in this case their quality is especially important - or be sure to make backups to external media.

If you work with valuable information, which to lose is tantamount to death, then you definitely need RAID 1- it is extremely difficult to lose information with it.

I repeat that Very it is desirable that the disks installed in RAID the array were gender identical. Size, brand, series, cache size - everything should preferably be the same.

Afterword

That's how things are.

By the way, I wrote how to assemble this miracle in the article: " How to create a RAID array standard methods ", and about a couple of parameters in the material " RAID 0 of two SSDs, - practical tests with Read Ahead and Read Cache". Use the search.

I sincerely hope that this article will be useful to you and you will definitely make yourself a raid of one type or another. Believe me, it's worth it.

For questions about creating and configuring them, in general, you can contact me in the comments - I’ll try to help (if there are instructions for your motherboard online). I will also be glad to any additions, wishes, thoughts and all that stuff.

If you have ever thought about purchasing servers or NAS storage, then you have probably heard the magical term “RAID”. RAID stands for Redundant Array of Independent Disks - a redundant array of independent disks. In general, systems with RAID use two or more hard drives either to improve performance or fault tolerance, or both. Fault tolerance, in this case, means that the equipment (for example, a server) will be able to work and data will not be lost even if one (or even more) of the disks fails.

In order to understand exactly how RAID helps improve performance and fault tolerance, you need to understand what RAID levels are. The RAID level depends on how many disks are in the array, how critical a possible disk failure is, and how important the system speed is. For example, for business applications, data safety in the event of component failure is much more important, but for home users, speed may be a deciding factor. RAID levels represent different combinations of balancing performance, fault tolerance, and cost of the solution.

RAID Technology Overview

As a rule, RAID is used in companies where fault tolerance and performance are not a luxury, but a necessity. Servers and NAS storages, in most cases, are equipped with so-called RAID controllers - hardware modules that manage arrays of SATA or SSD drives. Also, in most modern operating systems Software RAID is supported, where disks and arrays are managed by the operating system itself.

What RAID level do I need?

As already mentioned, there are several levels of RAID, depending on what you want to achieve - greater performance, greater reliability, or both. It is also important whether hardware or software RAID is used. Software RAID does not support all levels, and if you use hardware RAID, you need to think about choosing the appropriate controller.

The most common RAID levels.

RAID0 – used to improve performance. Also known as an "interleaved" array. This means that the data stream is sort of divided across several disks, instead of using one all the time. In this way, “parallelism” of reading or writing is achieved, which speeds up the work. RAID0 requires a minimum of two disks. RAID0 is supported by both hardware and software solutions. The disadvantage of RAID0 is that there is no fault tolerance - if any disk fails, information is lost.

RAID1 – used to improve reliability. Also known as a "mirrored" array. From the name it is clear that in the case of RAID1, information is simultaneously written to two disks, resulting in two copies of the data - two “mirrors”. If one of the disks fails, the second one continues to work and no data is lost. This is the simplest and relatively inexpensive way to increase fault tolerance. The disadvantage of this solution is slight decrease productivity. RAID1 requires a minimum of two drives. RAID1 can be assembled either in software or using a hardware controller.

RAID5 is probably the most common RAID configuration. RAID5 provides better performance than “mirroring”, also providing fault tolerance. In a RAID5 configuration, blocks of data and so-called parity (an additional block of data to be recovered) are written sequentially across three or more disks. If one of the disks fails, data is recovered from the remaining blocks and parity automatically and seamlessly. Naturally, in this case the system remains fully operational. Another advantage of RAID5 is “hot swap” - the ability to change any of the disks without interrupting the operation of the system (server or storage). A negative aspect of using RAID5 is a sharp decrease in performance during data recovery on a newly replaced disk. Also, RAID5 is, in principle, demanding on computing resources, so it is recommended to use a hardware controller, although programmatically It is also possible to create RAID5.

RAID10 is a combination of RAID1 and RAID0. Combines RAID1 "mirroring" and RAID0 "striping". Provides good performance and fault tolerance, but are quite expensive, because they require at least four disks and total capacity the array will be equal to half the capacity of the physical disks.

There are other RAID levels - RAID2, RAID4, RAID7, RAID50, RAID01, in most - they are specific combinations and variants of the configurations already described. For small businesses and typical solutions, the most common levels are 0, 1, 5 and 10.

It is worth mentioning that if you use disks of different capacities, the array will be equal to the capacity of the smallest disk. For example, the capacity of RAID1 of two disks 1000 GB and 500 GB will be equal to 500 GB. It is quite natural that for RAID it is recommended to use disks of the same capacity.

Also, for performance and reliability reasons, it is recommended to use disks of the same model and preferably within the same batch. Different disks, especially different manufacturers, can wear out and cause delays in completely unpredictable ways.

It's good to remember that RAID does not replace backup. RAID may be in a great way improving reliability and performance, but this is only part of a data recovery strategy.

Hard drives play an important role in a computer. It is stored on them various information user, the OS is launched from them, etc. Hard drives do not last forever and have a certain margin of safety. And each hard drive has its own distinctive characteristics.

Most likely, you have heard at some point that so-called raid arrays can be made from ordinary hard drives. This is necessary in order to improve the performance of drives, as well as ensure the reliability of information storage. In addition, such arrays can have their own numbers (0, 1, 2, 3, 4, etc.). In this article we will tell you about RAID arrays.

RAID is a collection of hard drives or a disk array. As we have already said, such an array ensures reliable data storage and also increases the speed of reading or writing information. There are various RAID array configurations, which are marked with numbers 1, 2, 3, 4, etc. and differ in the functions they perform. By using such arrays with configuration 0 you will get significant performance improvements. A single RAID array guarantees complete safety of your data, since if one of the drives fails, the information will be located on the second hard drive.

Essentially RAID array– this is 2 or n number of hard drives connected to the motherboard, which supports the ability to create raids. Programmatically, you can select the raid configuration, that is, specify how these same disks should work. To do this, you will need to specify the settings in the BIOS.

To install the array we need motherboard, which supports raid technology, 2 identical (completely in all respects) hard drives, which we connect to the motherboard. In the BIOS you need to set the parameter SATA Configuration: RAID. When the computer boots, press the key combination CTR-I, and already there we configure RAID. And after that, we install Windows as usual.

It is worth paying attention to the fact that if you create or delete a raid, then all information that is on the drives is deleted. Therefore, you must first make a copy of it.

Let's look at the RAID configurations we've already talked about. There are several of them: RAID 1, RAID 2, RAID 3, RAID 4, RAID 5, RAID 6, etc.

RAID-0 (striping), also known as a zero-level array or “null array”. This level increases the speed of working with disks by an order of magnitude, but does not provide additional fault tolerance. In fact, this configuration is a raid array purely formally, because with this configuration there is no redundancy. Recording in such a bundle occurs in blocks, alternately written to different disks of the array. The main disadvantage here is the unreliability of data storage: if one of the array disks fails, all information is destroyed. Why does this happen? This happens because each file can be written in blocks to several hard drives at once, and if any of them malfunctions, the integrity of the file is violated, and, therefore, it is not possible to restore it. If you value performance and regularly make backups, then this array level can be used on your home PC, which will give a noticeable increase in performance.

RAID-1 (mirroring)– “mirror mode”. You can call this level of RAID arrays the paranoid level: this mode gives almost no increase in system performance, but absolutely protects your data from damage. Even if one of the disks fails, exact copy lost will be stored on another disk. This mode, like the first, can also be implemented on a home PC for people who value the data on their disks extremely highly.

When constructing these arrays, an information recovery algorithm is used using Hamming codes (an American engineer who developed this algorithm in 1950 to correct errors in the operation of electromechanical computers). To ensure the operation of this RAID controller, two groups of disks are created - one for storing data, the second group for storing error correction codes.

This type of RAID has become less widespread in home systems due to the excessive redundancy of the number of hard drives - for example, in an array of seven hard drives, only four will be allocated for data. As the number of disks increases, redundancy decreases, which is reflected in the table below.

The main advantage of RAID 2 is the ability to correct errors on the fly without reducing the speed of data exchange between the disk array and the central processor.

RAID 3 and RAID 4

These two types of disk arrays are very similar in design. Both use multiple hard drives to store information, one of which is used exclusively for hosting checksums. For creating a RAID 3 and RAID 4, three hard drives are enough. Unlike RAID 2, data recovery on the fly is not possible - information is restored after replacing a failed hard drive over a period of time.

The difference between RAID 3 and RAID 4 is the level of data partitioning. In RAID 3, information is split into individual bytes, which leads to serious slowdowns when writing/reading large quantity small files. RAID 4 splits data into separate blocks, the size of which does not exceed the size of one sector on the disk. As a result, the processing speed of small files increases, which is critical for personal computers. For this reason, RAID 4 has become more widespread.

A significant disadvantage of the arrays under consideration is the increased load on the hard drive intended for storing checksums, which significantly reduces its resource.

RAID-5. The so-called fault-tolerant array of independent disks with distributed storage of checksums. This means that on an array of n disks, n-1 disk will be allocated for direct storage data, and the latter will store the checksum of the n-1 stripe iteration. To explain more clearly, let's imagine that we need to write a file. It will be divided into portions of the same length and will alternately begin to be written cyclically to all n-1 disks. A checksum of bytes of data portions of each iteration will be written to the last disk, where the checksum will be implemented by a bitwise XOR operation.

It’s worth warning right away that if any of the disks fail, it will all go into emergency mode, which will significantly reduce performance, because To put the file together, unnecessary manipulations will be performed to restore its “missing” parts. If two or more disks fail at the same time, the information stored on them cannot be restored. In general, the implementation of a level 5 raid array provides sufficient high speed access, parallel access to various files and good fault tolerance.

To a large extent, the above problem is solved by constructing arrays using the RAID 6 scheme. In these structures, a memory volume equal to the volume of two hard drives is allocated for storing checksums, which are also cyclically and evenly distributed to different disks. Instead of one, two checksums are calculated, which guarantees data integrity in the event of simultaneous failure of two hard drives in the array.

The advantages of RAID 6 are a high degree of information security and less performance loss than in RAID 5 during data recovery when replacing a damaged disk.

Disadvantage of RAID 6 - reduction overall speed data exchange by approximately 10% due to an increase in the volume of necessary checksum calculations, as well as due to an increase in the volume of written/read information.

Combined RAID types

In addition to the main types discussed above, various combinations of them are widely used, which compensate for certain disadvantages of simple RAID. In particular, the use of RAID 10 and RAID 0+1 schemes is widespread. In the first case, a pair of mirrored arrays are combined into RAID 0, in the second, on the contrary, two RAID 0 are combined into a mirror. In both cases, increased security of RAID 1 information is added RAID performance 0.

Often, in order to increase the level of protection of important information, RAID 51 or RAID 61 construction schemes are used - mirroring of already highly protected arrays ensures exceptional data safety in the event of any failures. However, it is impractical to implement such arrays at home due to excessive redundancy.

Building a disk array - from theory to practice

A specialized RAID controller is responsible for building and managing the operation of any RAID. Much to the relief of the average user personal computer, in most modern motherboards these controllers are already implemented at the level south bridge chipset. So, to build an array of hard drives, all you need to do is purchase the required number of them and determine the desired RAID type in the appropriate section BIOS settings. After this, instead of several hard drives in the system, you will see only one, which, if desired, can be divided into sections and logical drives. Please note that those who are still using Windows XP will need to install an additional driver.

And finally, one more piece of advice - to create a RAID, purchase hard drives of the same capacity, the same manufacturer, the same model, and preferably from the same batch. Then they will be equipped with the same logic sets and the operation of the array of these hard drives will be the most stable.