I have 2 disks of the same size, one has a win7 system, now it’s done as in the screenshot, but what confuses me is the fact that the 100MB area is not mirrored.

How to mirror the system partition so that if you physically remove 1 disk (when it fails) win7 can boot just as easily?

Something terrible happened, after I completed the work normally (but apparently the disks did not finish resynchronizing), the computer did not want to boot and hangs on “Verifying DMI pool data”.

I tried to disconnect 1 disk alternately, in one case it also writes.
I tried explicitly selecting the boot disk through F12.
I tried to restore Windows from a flash drive (I installed win7).

And nothing helped, despite the fact that it was written that the partition table had been restored.

This is what the boot disk shows when viewed through the command line using diskpart

Moreover, ubuntu and win7 load normally from other separate physical test disks.

Disk Mirroring in Windows 8 and Windows 7

Hard drives are the main storage devices for information on a computer. But, unfortunately, they do not last forever. And it’s very annoying one day to realize that “what you’ve accumulated through back-breaking labor” suddenly disappears due to disk failure. In some cases, data can be recovered. But usually only partially. And that's not always the case.

How to protect yourself from data loss on hard drives? There are several options to solve this problem.

The simplest one is to periodically dump important data onto external media: DVD/Blu-ray discs, flash drives, external hard drives. The option is generally quite reliable, but not entirely convenient: you need to remember and find time to back up your data, in addition, the data from the last copy to the disk failure will still be lost.

In order not to bother with external media, you can install another HDD in your computer and periodically copy data to it. It would be even better if this was done automatically.

This kind of automation has been in use for a long time and is expressed in so-called RAID arrays. These are arrays of hard drives combined in a special way. There are several types of RAIDs, the most popular of which are “RAID-0” - 2 disks are connected in series for faster reading and writing of data, and “RAID-1” - 2 disks are connected in parallel for simultaneous writing of data to both HDDs at once. If one of the disks fails, there is another disk with a mirror copy of the data, and the likelihood of two disks failing at the same time is very small. RAID-1 is usually called a “mirror”, and the parallel connection of several disks is called “mirroring”.

To implement a disk array, a RAID controller must be installed in the computer. It can be built into the motherboard or installed separately.

My personal experience with RAID controllers built into the motherboard is quite poor. As a rule, manufacturers, in order to reduce the price of the product, use inexpensive controllers, the reliability of which leaves much to be desired. Individual controllers of good quality cost at least hundreds of dollars.

In this regard, recently the so-called “software RAIDs” have become increasingly popular, i.e. parallel recording of data on 2 disks is performed not at the hardware level, but at the software level. A special program monitors all data writing operations on a specific disk and writes the same data to another disk.

In the Windows 7 and Windows 8 operating systems, developers have built software RAID into the OS itself, i.e. You can implement data mirroring using Windows tools.

I would like to make a reservation right away that this functionality is not suitable for those who like to install several operating systems on one computer. In the end, only the OS that was used for mirroring will remain working. And if you perform the steps incorrectly, then there will not be a single working OS left. Later in the article I will pay attention to these points and tell you how to avoid such mistakes.

If your computer only has one operating system, you can safely use everything described below; your Windows is in no danger.

So, in order to see all the pitfalls of data mirroring using OS tools, I use a computer with 2 operating systems installed - Windows 7 and Windows 8. Windows 7 was installed first, and then Windows 8 was installed on another logical drive. We will perform the mirroring itself in Windows 8.

What is needed for this? The computer must have 2 physical hard drives. It cannot be otherwise - copying disk data onto the disk itself makes no sense, since when the disk is erased, we will lose both the data and their copy at the same time. The advantage of software RAID is that, unlike hardware RAID, it can be configured for individual logical drives, and not just for the entire physical drive as a whole.

To create a mirror, you must enter Disk Management. To do this, go to the Control Panel and select “Administration”.

Administration section in Control Panel

In Administration we find “Computer Management”.

Administration Tools

In the Computer Management window on the left, select "Disk Management".

Disk management

From the figure you can see that the computer has 2 physical disks - “Disk 0” and “Disk 1”. We will create a mirror for logical drive F (New Volume), located on Disk 0. The volume of this partition is 10GB. We have a second HDD (Disk 1), with a capacity of 12GB, which we use as a mirror. The second disk must have unallocated free space, the amount of which is not less than the size of the mirrored disk. We have 12GB of unallocated space on Disk 1, i.e. there are no logical drives in this space.

Right-click on the desired section and select “Add Mirror” from the context menu.

Adding a mirror

The system will prompt you to select a disk that will be used as a mirror.

Selecting a disk to create a mirror

Select the desired disk from the list and click “Add mirrored volume”. Here's an interesting warning:

OS warning about the impossibility of running other versions of Windows

We are warned that the disks will be converted to dynamic ones and if several operating systems are installed on the computer, then after performing this operation only the currently running OS will remain working. Let's check this later. Click "Yes".

The process of creating a mirror will begin - if there is any data on the F drive, it will be copied to the mirror disk.

Synchronizing disks when creating a mirror

After completing all the processes, we get this picture.

Result of creating a disk mirror

As you can see, the system took space from the second disk, the volume of which is equal to the volume of the mirrored disk. The rest of the space on the second disk remains unallocated and can be used at your discretion, for example, to create another logical disk there.

Let's check if we can now boot the second OS installed on the computer. Let me remind you that in my case, Windows 7 and Windows 8 are installed, we performed all the steps under Windows 8. Let's try to load Windows 7.

We reboot the computer and get a list of OS selections.

Selecting the boot OS

We select Windows 7, the boot process begins and... we get this.

Windows 7 boot error

Now about the pitfalls that I mentioned at the beginning of the article. It’s not for nothing that I said there that Windows 8 was installed after Windows 7. What does this affect? The fact is that a computer can only have one OS bootloader. And the bootloader is always the bootloader of the last installed operating system - it overwrites the previous bootloader found on the disk. But at the same time, during the installation process, Windows, having found previously installed operating systems on the computer, configures its boot loader in such a way that it provides the user with a list of installed operating systems at startup. From this list we select which OS we want to run now. In my case, the Windows 8 bootloader starts, which was the last one installed, and offers a list of operating systems found. Now let's imagine that I configured mirroring not in Windows 8, but in Windows 7. In this case, Windows 8 would become inoperable. And along with it, its bootloader would cease to function and I would lose the opportunity to launch any OS on my computer at all - this has been verified by experience. The only solution to this problem is to reinstall Windows.

Thus, if your computer has several operating systems installed, you can configure mirroring only in the last installed OS, while all other operating systems will automatically become inoperable and it will be impossible to bring them back to life- we'll see this later .

I repeat once again, if you only have one operating system, everything we are talking about will not cause the slightest harm to it or the computer as a whole.

So, the mirror is configured, now all data written to the disk will be automatically written to another disk. How to check that it works?

Let's open a list of computer disks through Explorer.

Computer disks after setting up a mirror

In Explorer we see the “New Volume F” disk; its mirror is not here and should not be, since everything happens at a level invisible to the user. Let's try to write some data on disk F. I'll just create a folder and a text file in it.

Folder and file on disk

If everything works correctly, the same folder and file should have been created on another disk - a mirror. To clarify this, let’s “disassemble” the mirror.

Again, go to disk management, right-click on any of the 2 mirror disks and select “Split mirrored volume.”

Splitting a mirrored volume

Windows will warn us that after this action, data storage reliability will no longer be at such a high level. We agree.

Windows warning when splitting a mirrored volume

As a result, we will get two separate logical drives. The system immediately assigned the letter G to the new disk (former mirror).

Mirror split result

Now in Explorer, in addition to the F drive, we will also see the created G drive.

Computer disks after splitting the mirror

And on both previously mirrored disks we will see the folder we created, and inside it a file.

Result of data mirroring

We made sure that the mirror works and, if necessary, we can “disassemble” it without any data loss.

Will we be able to boot a second OS after splitting the mirror? We try and as a result we get this again.

Error loading second computer OS

Thus, by setting up mirroring, you will forever lose the ability to run other installed Windows operating systems on your computer.

The downside of disk mirroring is the loss of space - we use two disks as one. But information costs more than disks. If you still need additional disk space, the mirror can be divided, as shown above - in this case we will get 2 disks with the same data, or simply remove one of the disks from the mirror - then we will get one disk with data and a second disk with unallocated region.

To remove a disk from a mirror, just right-click on one of the mirrored disks in the disk management window and select "Remove mirror".

Removing a disk from a mirror

Selecting a disk to remove from the mirror

Click “Delete mirror” and we get this picture.

Disks after removing the mirror

The disk from which the mirror was removed returned to its original state - it is now not dynamic, but again basic, but Disk 0 remains dynamic, which means we still won’t launch the second OS from it.

And one more subtlety is that if we remove the mirror from Disk 0, it will not become basic, but will remain dynamic.

The system disk remains dynamic after removing the mirror

Thus, by creating a mirror, we deprive ourselves of any chance of using a second OS on the computer.

But it’s not so often that at home you have to install several operating systems on one computer, but almost everyone needs data backup. Therefore, this opportunity is very useful and I advise you to use it. All that is needed for this is Windows 7 or Windows 8 installed on your computer, as well as an additional hard drive of the required size.

In this article, I will give an overview of the possibilities for organizing RAID arrays using the built-in tools of Windows Server and detail what pitfalls can be encountered when creating and operating such arrays.

Software RAID Features in Windows Server

The following arrays are supported:

• striped volume (RAID0)
• mirror volume (mirrored volume, RAID1)
• RAID5 volume
• spanned volume (one logical volume is located on more than one physical disk)

Dynamic disks

RAID arrays can only be created on dynamic disks - a special layout of physical disks (understandable only by Windows), which has the following features:

• A regular (basic) disk can only be converted to a dynamic disk as a whole.
• Converting a dynamic disk back to a basic disk is possible, but only if you remove all volumes from the dynamic disk.
• A dynamic disk is one large NTFS partition, on which, with the help of clever service information, a large number of volumes (both simple and RAID) can be placed; it is possible to resize simple volumes using standard Windows tools. However, I don’t know how optimally and fragmented the data will be located.
• The cloning, recovery, and disk resizing programs I know of do not support dynamic disks.
• Dynamic disks containing RAID volumes can be moved to another computer running Windows Server, as they contain the necessary information for the correct assembly of the array.

Unable to create volumes with different RAID levels

You can only create RAID volumes of one type (level) on one group of physical disks. For example, if we have 3 physical disks and we created a RAID5 volume on them without taking up all the space. We will not be able to create volumes of other RAID levels (RAID0 and RAID1) in free space, but only RAID5 and simple volumes.

Simultaneous volume synchronization

If several RAID volumes are created on one disk group, then in the event of any failure after the computer boots, they begin to be restored simultaneously. This is a fierce, furious EPIC FAIL! A simple situation: there are two physical disks, two RAID1 volumes have been created on them, one for the operating system, the other for data.

This scheme works great until the first failure (the simplest types are a sudden power outage or a blue screen). And then horror comes. The operating system boots and at the same time begins to simultaneously synchronize both RAID1 volumes. Thus, the physical disks receive competing commands for intensive sequential operations in three different physical areas at once. At the same time, the disk mechanics wear out wildly, the cache is useless.

From the outside, such “failure tolerance” looks like this: the overall performance of the disk subsystem drops by a factor of 20, the OS itself will boot either after synchronization of one of the volumes is completed (15 minutes, if it is small, 50 gigabytes), or after 20 minutes and will be useless until end of synchronization of one of the volumes.

I consider the above behavior to be an unacceptable architectural miscalculation on Microsoft's part and am surprised that this problem has not yet been resolved since the advent of software RAID in Windows 2000 Server.

If you find yourself in the situation described, then you should not wait for the OS to load and the disks to wear out.

1. Disconnect one of the physical disks.
2. Boot into the OS at normal speed.
3. Break the mirror, turning RAID1 volumes into simple ones.
4. Connect the second drive back.
5. Create only one mirror for the volume you need.

RAID5

I will describe a scenario in which you will not be able to restore a degraded RAID5 array to a healthy state, even if all the conditions are provided for this.

1. There is a RAID5 array of six disks (Disk1-Disk6).
2. Among them there is one faulty Disk1 (for example, a couple of megabytes of a terabyte volume cannot be read), but the operating system does not yet know about this and has not marked it as faulty.
3. For some reason, the working Disk2 was disconnected from the array.
4. Following the logic of RAID5, if one disk fails, the functionality of the array is preserved, such an array is marked as degraded, its operating speed drops sharply, and synchronization with a new working disk is required.
5. The working Disk2 is connected into place. The system recognizes it as faulty. To synchronize the array, this failed disk must be removed from the RAID5 array and defined as empty.
6. Everything is ready to synchronize the array. We run the array repair (repair) on the empty Disk2.
7. SUDDENLY synchronization encounters read errors on the truly faulty disk Disk1 and stops.
8. The massif remains degraded. Disk1 is marked as containing errors, Disk2 is marked as online, but due to interrupted synchronization it does not contain completely correct data.
9. In the hope of recovery, a completely new, working Disk7 is connected. The array is restored to it.
10. As a result, the working Disk2 is replaced with another working Disk7, but synchronization is interrupted again, having found an error on the faulty disk Disk1.
11. And so on through the cycle.

There is nothing you can do except copy the data that is still being read and rebuild the entire array.

Not wanting to admit defeat, I tried the following things:

• Synchronize the array while skipping read errors on disk Disk1 (after all, these are just megabytes of a whole terabyte). But Microsoft does not provide such an option.
• Rewrite the entire failed Disk1 sector-by-sector to another healthy disk using cloning programs. However, the programs available to me with dynamic disks did not work.

An example of a competent implementation of software RAID

The hardware and software implementation of the RAID controller, known as Intel Matrix Storage, and recently renamed Intel Rapid Storage (works on RAID versions of chipsets such as ICH9R, ICH10R) has been eliminated from the above disadvantages. Intel's hardware and software RAID provides many of the benefits of mature RAID controllers:

• ability to identify hot-swappable disks
• ability to create volumes of different RAID levels on one disk group
• sequential synchronization and verification of RAID volumes on a disk group

Its main disadvantage, in contrast to fully hardware RAID controllers, remains “software”, from which follow:

• lack of built-in cache and the ability to work autonomously in case of an accident
• completely depends on the operating system and drivers
• operations performed on the disk subsystem load the main processor and memory
• lacks support for advanced compute-intensive RAID levels such as RAID6

useful links

• What are dynamic disks - Windows IT Pro [quite old article]
• The whole truth about dynamic disks - Hacker [read carefully, the “whole” truth is mixed with fables]

Hello friends! If you look at the comments from readers on our website in the section on hard drive repair, you will be amazed at how many people were not prepared for the fact that their storage device suddenly failed and all their important files: projects, plans, diplomas, drawings, calculations, etc. which a person worked for several months in a row simply disappeared into nowhere. It’s difficult even for a professional repairman, let alone an ordinary user. Therefore, eIf personal data is important to you, then be sure to read today’s article. In it we will show you how to createRAID-1 array of two HDDsin the latest Windows 10Fall Creators Update. This is very easy to do, because technology« disk mirroring» built into the operating system.

This article differs from because "Mirror» we will create directly for the system drive (C:) and directly in running Windows 10!

At the beginning of the article, let me remind you, that a RAID array or “Disk Mirroring” is the parallel recording of data on two hard drives. If one breaks down HDD all information remains safe and sound on another hard drive. That's the whole secret!To better assimilate the information, let’s look at everything using a specific practical example, so you will understand everything much better than if I were to tell you the theory now.

Creating a RAID array or Mirroring disks in the latest Windows 10 Fall Creators Update

Let's take a regular computer in the organization where I work.

Right-click on the Start menu and select "Disk Management".

In this window, you can see two hard drives connected to the PC.

The first disk (Disk 0) contains two partitions: (C:) and (D:). On disk (C:) Windows 10 installed. The OS desktop contains important work folders. If the folders disappear for some reason, the work of the entire organization will stop for several days and I’m even afraid to imagine all the consequences. On disk(D:) there is no serious information, only movies and photographs. Therefore, I will create a mirror for one system partition(C:).

The second hard drive (Disk 1) is absolutely blank and contains no partitions, its entire area is unallocated. It is on this that we will create a disk mirror (C:). All information recorded on the system disk will also be duplicated on the mirror disk.

It is important that the HDD from which we want to create a mirror has no partitions and is no smaller in size than the original disk on which the operating system is installed. In our case, both hard drives are absolutely identical.

Right-click on the drive (C:) and select “Add mirror...”

Windows 10 will prompt you to select the disk that we want to use as a mirror. Left-click on blank Disk 1 and click« Add a mirrored volume».

A warning appears about The fact is that now the disks will be converted to dynamic ones and if you have multiple operating systems installed on your PC, then after conversion you will only be able to load the current operating system. Will explain.

Tune RAID-1 array or “Disk Mirroring” is better only if you have one operating system installed on your computer that has one bootloader. If you have several operating systems installed on your PC, for example, Windows 8.1 and Windows 10, then you can mirror disks in the Windows that was installed last. That is, you have installedWindows 8.1, then Windows 10, in this case we configure RAID-1 array in Windows 10 and after that only Windows 10 will boot on the computer. If you configure RAID-1 array in Windows 8.1, then no Windows will load on the PC at all. This problem is connected with the peculiarity of the operation of dynamic disks, which would be a good idea to write a separate article about, but everyone never gets around to it.

There is only one OS installed on my computer. I press “Yes.”

The process of disk resynchronization begins when a mirror is created. In simple words, Windows 10 creates an exact copy of the drive (C:) on a second hard drive (Disk 1).You can create a partition from the unallocated space and use it without any problems.

The resynchronization process is completed and the OS is ready for use.

How to protect Windows from problems caused by hard drive damage? For this purpose, there is a backup mechanism, in particular, one with automatic creation of incremental or differential backups to maintain the current state of the OS. But there is an alternative solution - mirroring Windows system partitions, performed by its own standard means.

This is the creation of software RAID in configuration RAID 1 in order to preserve information and gain access to the OS environment in case of problems caused by problems with the hard drive that ensures its existence. What are the features of this mechanism, and how to implement it in the Windows environment - we will talk about all this in detail below.

1. Windows Mirroring: What is it?

Mirroring- this, as mentioned, is software RAID 1 , a commonly used disk array configuration in which data is duplicated on a second hard drive called a mirror. If problems arise with the first, main hard drive, using a mirror we will be able to access our valuable information. Moreover, if mirroring is applied to Windows system partitions, if the main disk fails, we will not only gain access to the information stored in the system, we will even get inside it. Not inside the original one, but inside its exact clone on the mirror disk.

Implementation of software RAID 1 possible under dynamic disk technology. This technology exists in the Windows environment, starting with version 2000 . The technology itself is applicable to both MBR- and to GPT-disks, but here is the creation of software RAID 1 complicated by the need for additional command line operations. So everything that will be suggested below concerns only MBR-disks. Software creation RAID possible only in OS editions starting from Pro.

When reinstalling the system on dynamic disks, there is no need to introduce specific drivers into the distribution kit RAID-controller, as required for hardware RAID. Just as there is no need to reinstall anything when using any of the software configurations RAID. However, when working with dynamic disks, we will not be able to use more than one Windows. OSes installed on other partitions simply will not boot. Technology works according to the rules “Entrance is a ruble, exit is two”: the original basic disks with the structure and data provided by Windows are converted into a dynamic type easily and simply, but the opposite direction only works for disks with unallocated area. If the structure and data are there, you will have to resort to third-party software.

Another important nuance: to work with this technology, it is important that the computer name contains only Latin characters. Otherwise we will get an error "Invalid package name".

2. Preparatory stage

For application to Windows software RAID 1 A second hard drive with a capacity of at least the total volume of both system partitions must be connected to the computer. In our case, they occupy, respectively, 549 MB And 60 GB, and the mirror disk has a capacity with a small margin – 70 GB. The mirror must be prepared for its further fate - all partitions on it must be deleted. There should be a clean unallocated area left.

It is better to remove information about loading Windows installed on other partitions, if any, and leave the option to launch only the current system. When mirroring, the boot menu will be overwritten, and there will be a record of loading only one OS with the addition of the ability to launch its clone on the mirror disk. So it is important that there is a record of the download of the required Windows. Otherwise we get BSOD .

We will implement mirror Windows using the system utility diskmgmt.msc, it's also a console.

3. Convert the disk to dynamic

On any of the two disks, call the context menu, select converting them to dynamic type.

We tick both of them. Click "OK".

Click and confirm the action.

4. Creating mirrors of system partitions

So, both disks - the main one and the mirror - are now dynamic. Calling the context menu on a small technical section of the system (bootloader section) . We choose.

Click on disk mirror. Click.

Afterwards we will see how a clone partition has been formed on the mirror and the data synchronization process has started.

Now click on the context menu on the main Windows partition, on the disk WITH . And we perform the same operation as above.

Now we have configured data synchronization with the mirror. We can dispose of the unallocated area remaining on the mirror disk as we please: leave it as is, create a separate partition from it, attach the space to some other partition (and on any of the disks, because we are now working with their dynamic type) .

5. Mirror Windows

As soon as the data is synchronized with the mirror, and we learn about the completion of this process by the degree of load on the disk in the task manager, we can reboot and test the performance of the mirrored Windows. Access to it, as mentioned, will appear in the bootloader menu, it will be listed with the inscription “Windows such and such version is secondary plex” . By the way, the bootloader menu in the last two versions of the OS can be configured directly at the computer startup stage.

You can set a shorter time for Windows auto-selection.

The system on the main disk will boot first, so you can select the minimum 5 second to display download options.

In older versions of Windows, the timeout for the bootloader menu is configured in the system utility "System configuration".

Mirror Windows- This is a complete clone of the main system. Here we can do everything the same as in the original environment. If anything happens to the main HDD or SSD, disable it in hardware, start the computer and press F9 on the boot error screen OS.

6. Removing Windows mirrors

If Windows mirroring is no longer needed, its mirror can be deleted. This is done in the same place where this mirror was added - in the utility diskmgmt.msc. Click on each of the system partitions in turn and click on the context menu.

Select the mirror disk, click the delete button and confirm.

The mirror disk space will turn into unallocated area, and its type is converted from dynamic to the original base.

7. Reinstalling Windows under mirroring conditions

Reinstalling Windows in the conditions of the existence of mirrors of its partitions is carried out in the same way as usual - we can delete two of its partitions and specify an unallocated area as the OS installation location, or we can simply format its two existing partitions.

In any of these cases, when you reinstall Windows, its mirror will not go anywhere; it will continue to function in the new system. Program RAID 1 is transferred to a new, reinstalled system environment. And everything would be fine if we mirrored regular user sections with our data. But software RAID 1 for system partitions, remember, it also provides the ability to enter Windows on a mirror disk. And here we are faced with another Microsoft jamb: the record about loading the mirror system will be lost - that same bootloader menu item with an additional entry "secondary plex" . After all, we formatted or deleted a small bootloader section when installing the system. Leaving it as is and not formatting it is even more dangerous. Let's remember that on dynamic disks only one Windows can be loaded. If the bootloader partition is not formatted, the new system will be listed second in the boot menu and will not be able to start. Likewise, neither the first system nor its mirror will start, because the first one no longer exists, and its mirror is a clone of the non-existent Windows.

So the Windows boot partition must either be formatted or deleted when reinstalling it. How, then, to ensure login to mirrored Windows? The solution here is very simple: you need to re-create the mirrors of the system partitions - delete them, as discussed in the previous paragraph, and re-assign them. The mirror disk is re-synchronized with the system partitions, and the mirror system item with an additional entry will again appear in the Windows boot loader menu "secondary plex".