How to Recover Files From RAID 6 After a Controller Issue or Disk Failure

Alas, this terrible thing has happened… and your new RAID 6 no longer shows any signs of life. What to do? Who to call? What’s wrong? How to recover all that data? In our article, you will find all the answers to your questions.

How to Recover Files From RAID 6 After a Controller Issue or Disk Failure

Introduction

RAID systems are among the most reliable and best-performing storage solutions, but even they are not immune to damage and failures. The whole system stops working when one of the physical storage devices breaks down, when the file structure suffers from failures, or when the controller no longer works properly. Even a disk array based on the most expensive hardware can fail or break down – it’s only a matter of time. That is why it is always a good idea to back up all mission-critical files from time to time – unless you want to be forced to use the big guns, that is, specialized data recovery software.

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How to Recover RAID 6 Data After Three Disks Fail, the Controller Breaks Down, or the Array Rebuilt

How to Recover RAID 6 Data After Three Disks Fail, the Controller Breaks Down, or the Array Rebuilt

RAID 6 is the redundant array of independent disks which features a high degree of tolerance against loss of information. This configuration type requires at least four disks and it uses striping with dual parity. For building the array, we’ll be using SAS RAID controller Adaptec 6805T and six hard disks, and all the tests will be conducted with this hardware configuration.

There are two ways to build the storage system: with the help of BIOS or with the specialized software supplied by the controller vendor, and we’ll explore both.

How to build a RAID 6 with the help of BIOS

Boot the computer as always, and press the key shortcut Ctrl+A to access BIOS.

Open BIOS by pressing Ctrl+A

Go to Array Configuration Utility.

Select the line Array Configuration Utility

The next step is initialization; do it by jumping to the line Initialize Drives, press Enter.

Initialization with the Initialize Drives option

Use the Space or Insert key to select the drives which would make up your storage system, and press Enter to confirm the action.

Select the drives to include into the array

The system reacts with the warning that all drives to be initialized will be erased. Enter Yes, the operation will be confirmed.

The system warning about erasing the drives

Wait until the process is over, and then start building the array. Select the line Create Array.

Main menu in  Create Array utility

Select the drives you need to combine into a storage system, and press Enter.

Select the drives you need to combine into a storage system

In the new window, specify the following: name, type, block size, capacity, and some extra properties.

Specify the name, type, block size, capacity, and some extra properties

An important note: These details must be memorized or written down, because you’ll need them when you start recovering the array data. When proper values are selected, press Enter to confirm.

Build a RAID with the help of Adaptec Storage Manager

We’ll be using specialized software – Adaptec Storage Manager, which can be downloaded from the official website of the adapter’s vendor. Go to the website, select the necessary version depending on the type of your operating system, download and install it.

Download Adaptec Storage Manager from the vendor’s official website

Start the utility, and click on the computer’s name in the main window of the program.

The main window of Adaptec Storage Manager, select the computer to work with

Enter the registration data and password to your account.

Enter the registration data

Now your controller should appear in this window.

The program has recognized the controller

Click on its icon to see the list of connected drives.

The list of drives connected to the adapter

To build an array, click Create.

Click Create to build a storage system

In the next window, choose between Express or Custom configuration options.

In Configuration Wizard, select Express or Custom

The first mode is automatic, and the utility will offer you the most suitable array type for your set of disks.

Express mode

In the second mode, you can select the configuration manually. In our case, we select the Custom option.

In the next window, select the array type. If you don’t see the one you need on this list, click Advanced Settings to find more options.

Advanced Settings for your array type

Select the RAID type you want -in our case, it’s RAID 6 – then click Next.

Select the required array type from the extended list in the Custom configuration

In the next window, fill in the field Name.

Enter the array name into the field Name

Click Next, type in\modify other properties, or leave them at their default values.

Type in main properties

All the properties should be written down or memorized, because you will need them when the time for data recovery comes.

After that, select all drives to be included into this RAID, and click Next.

Select all the drives to be included into the array

Click Apply to save the configuration, and then Yes.

Confirm and save the data

The untility will start building the array immediately.

The dialogue box to create an array

This is the stage that suggests waiting – it could be for twenty minutes, or even for several hours.

RAID 6 is ready

Now it can be used – as soon as you take the last step in Disk Management.

This utility can also be used to look up array properties and status, remove it or rebuild it, if necessary.

Adaptec Storage Manager - how to administer the array you have built

How to replace a hard disk in RAID 6

The technology used in RAID 6 is designed with improved fault tolerance in mind. It is built in such a way that it can work properly even if one or several physical disks are out of order. So after one or two physical storage devices break down, this RAID type will remain operable. While the computer is booting, you will see a system warning that says “Following Arrays have Missing or Rebuilding or Failed Members and are degraded” and the name.

Following Arrays have Missing or Rebuilding or Failed Members and are degraded

An important note: Before you start doing anything to repair the array, make sure you have backed up all your important files. That is important, because in the process of rebuilding the array, you may face some unexpected things like one more drive breaking down, a hardware failure in any other device or a software failure in the rebuilding process, and any of these may result in losing your files for good.

To find out which disk is out of order, use Adaptec Storage Manager.

Adaptec Storage Manager - open array properties

In order to see which drives are still OK, right-click on each of them and jump to open their Properties.

Properties of healthy drives

Find the line Serial Number for a particular HDD.

Serial Number

This is the same serial number as printed on the special sticker you can find on the physical disk.

Seagate Pipeline HD.2 with the capacity of 320 ГБ, the serial number on the sticker

When you find the drives which are no longer operable, all you can do is to replace them with new ones and rebuild your RAID 6. Now replace the old disks, connect the new disks, restart the computer, and after initialization, press the key shortcut Ctrl+A.

Press Ctrl+A to start the utility

In the controller’s menu, jump to Array Configuration Utility.

The list of commands for the Adaptec controller: go to Array Configuration Utility

Now select the line Initialize Drives.

Select Initialize Drives

The new drives need to be initialized. Press the Insert key to select them, and then Enter – to confirm the operation.

The new drives need to be initialized

Now add the new disks to the array by jumping to the line Manage Arrays.

Go to Manage Arrays

Press the key shortcut Ctrl+S, to open the management window.

Ctrl+S to open the management window

Use the Space key to select all the physical disks you need, then press Enter -> Yes to confirm your actions. The process of building the array starts at once.

Do you want to submit changes – select Yes

Now you can boot the server in an ordinary mode and continue your work; the entire process of building the disk array is a long story and it can take a lot of time.

Even when three physical disks break down, or the controller fails, you can still recover the data stored on such disks! We will use Hetman RAID Recovery.

Recover data from damaged RAID arrays inaccessible from a computer.

It will help you find the information from damaged arrays or physical disks included into such arrays. First of all, it will detect the technical data: controller model, software, motherboard. After that, it will rebuild the array, so all you have to do is to save the data.

How to recover files after a RAID controller fails

When the controller is broken, data from the disks can’t be read in the ordinary way. If you connect the disks directly to the motherboard, Windows will display a notification saying that the disks need to be formatted.

In this situation, you can either replace the controller with a similar one of the same series (but there is no guarantee that the array can be restored back to all of its functionality) or use specialized software tools capable of restoring your RAID and preserving all of its data.

On a computer running a Windows OS, connect the healthy disks directly to the motherboard. The operating system will identify them as damaged – RAW. And suggest to initialize them, if you open Disk Management.

Disk management and initialization of connected drives

Similarly, if you open them in the Explorer, you’ll be suggested to format them.

Format the disk to start using it

An important note: Hit Cancel everywhere, or all the information will be erased, and you won’t be able to rebuild the array.

You can download Hetman RAID Recovery from the official website, and then install it as administrator. Every disk within the array keeps all service data: the disks included into the array, the order of connection to the controller, how blocks are written, RAID type, number of groups, capacity.

Hetman RAID Recovery initialized the array

Right after the program starts, it runs an automatic search and initializes all storage devices connected to this computer. Having selected the required data from the operating system and connected disks, Hetman RAID Recovery will add automatically built RAID arrays to the list. It will rebuild the array on the fly, if the disks within it are healthy, and then you will only have to scan the volumes and save the information.

Open the Drive Manager tab in the utility, find the field RAID right-click on it and select Open.

Drive Manager and RAID arrays

Let’s run a Fast scan first, and if the internal structure of the disks is still undamaged, it will be enough for the program to find the files you need.

Run Fast scan first

After the fast scan, open the disk to look for the data you need: if the program hasn’t managed to find it, run Full analysis. When the analysis is over, you will see the detected files in the right side of the window.

Running Full analysis

As a result, Hetman RAID Recovery rebuilt the array easily and managed to find all the data.

Results of running full analysis on this array

Back up the most important files, and then just replace the controller with the most suitable one.

How to recover files with a dead RAID controller and two faulty disks?

Now let’s imagine a situation when the controller no longer works properly, and two disks do not respond at all. Thanks to the RAID 6 technology, even with two drives down your array is still operable. However, when the controller fails, you have to use additional software tools to access the files on the disks.

Just as before, we connected six disks to the computer. The program has identified the array type automatically.

 Hetman RAID Recovery starts and identifies the array type at once

Two of the disks don’t respond, but correct data on the array is displayed.

Information on the rebuilt storage

Right-click on the corresponding line, then click Open, and start the scan wizard.

Open the required drive

Run Fast scan first, and if the program displays all the necessary files, then you don’t have to run Full analysis.

Run Fast scan

Select all the files you need and click Recovery.

Select the files you need and click Recovery

Choose a directory on another disk where the recovered data should be saved, and click Recovery.

Specify the directory for saving

How to recover a RAID system missing a controller and three disks out of six?

Let’s explore a case when the controller refused to work properly, while three of the disks within the array are damaged. RAID 6 architecture cannot ensure proper operation in this scenario. Even if the controller is OK, the information will still be inaccessible. Even though you replace faulty disks and try to rebuild the array, the data will be lost completely.

Let’s start by connecting the three healthy disks to the motherboard. If you can’t identify which disks are out of order, and which are not, then connect them all. Even in this situation, Hetman RAID Recovery will be able to recognize the RAID type automatically, based on the additional information.

The array is recognized and added as a storage device

If the program can’t recognize it automatically, and it doesn’t add it to the list of devices, then you should add the integrated RAID Constructor.

The integrated RAID Constructor

Remember I told you to memorize or write down the properties when this array was created? It is now that we need this information for building the array manually.

Specify the properties

When the program recognizes the RAID type automatically, make sure that all the properties are displayed correctly. The amount of data available for recovery depends largely on this information. After checking the properties and correcting them if necessary, click Add to start scanning.

Click Add to start the scan

In our case, the program has found the necessary files, but some of them are damaged.

The data is located, but some of it is damaged

It’s recommended to run Full analysis, so that the utility finds more information and it improves your chances to find the files which are still intact.

The other steps are simple: check Preview, select the necessary files, and click Recovery.

Select files for saving

Select a directory to save the files to, and make sure it’s located on a different physical disk.

Select a directory for saving

When the process is over, all the files will be put into the directory you have selected.

Conclusion

At the moment, RAID 6 is one of the most reliable types of architecture in terms of ensuring data integrity. What is more, there are very little chances of three hard disks failing at the same time. If one of the disks breaks down, replacing it and rebuilding the array is a matter of several hours, and even with two disks down, the situation is not so bad. However, when the controller fails and there is no healthy disk to replace the bad one, you don’t seem to have a reliable way of accessing your data except by using specialized software. Our program has coped with the task perfectly. It was able to rebuild the array even when three disks were out of order. It also managed to recover files in spite of the damaged controller and two hard disks that failed completely. Even more, it found a way to extract a part of the files when three disks out of six became inaccessible.

Vladimir Artiukh

Author: Vladimir Artiukh, Technical Writer

Vladimir Artiukh is a technical writer for Hetman Software, as well as the voice and face of their English-speaking YouTube channel, Hetman Software: Data Recovery for Windows. He handles tutorials, how-tos, and detailed reviews on how the company’s tools work with all kinds of data storage devices. Read more

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