⚠️How to Recover RAID6 Data After Three Disks Fail, the Controller Breaks Down, or the Array Rebuilt
Dec 19, 2020 08:00 · 2241 words · 11 minute read
Hello everybody! Watch this video to find out how to recover data from a damaged RAID 6 array. You’ll see how to create a hardware RAID 6 with an Adaptec ASR-6805T controller, what to do if one of the disks within the array failed, how to identify the faulty disk, and how to replace it. Also, I’ll show you what to do and how to extract the information from the array if the controller has glitches, three disks don’t respond, or the whole RAID system is damaged. Even the most reliable RAID storage system may break down someday - it’s only a matter of time. However, as long as you have specialized software capable of recovering the lost information, your data is safe.
01:26 - Just as any other array type, RAID 6 is designed to ensure system safety and reliable data storage. 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. In today’s video, I’m going to show you how to build a RAID 6 array with six hard disks and an Adaptec ASR-6805T controller. We will run all tests on this RAID type. How to create a RAID 6 system A RAID 6 system can be created with BIOS features, or with specialized software supplied by the controller manufacturer.
02:05 - How to create RAID 6 with the help of the controller’s BIOS To access BIOS at startup after initialization of hardware, press the key shortcut
03:02 - Open the option “Create Array,” select the disks that your RAID is going to include, and press Enter. In the next window, specify the array type, name, capacity, block size and other properties. It’s better to memorize them because you will need this information when recovering data from the RAID system. After all properties are given, press Enter. How to create RAID 6 with the help of Adaptec Storage Manager Also, you can create a RAID system with the help of a special utility provided by the controller’s manufacturer.
04:01 - I’ll illustrate it with the example of Adaptec Storage Manager, which you can download from the official website. Download and install the version appropriate for your operating system. In the program’s window, click on the computer’s name and type the password to your account. When the password is accepted, the controller will be displayed; as you click on it, you will see the list of connected disks. To build a RAID, click the “Create” button and in the next window, select one of the options offered by the wizard – “Express” or “Custom.
” 04:36 - The first mode is automatic, and the utility will offer you the most suitable array type for your set of disks. In the second mode, you can select the configuration manually. In our case, it’s necessary to specify a particular RAID type, so I go for custom configuration. In the next window, select the array type. If you don’t see the one you need on this list, click Advanced Settings and then select the RAID type you want, then click Next.
05:12 - In the next window, you can enter the name of the disk array and change its properties, or leave them as they are. As I said before, it’s recommended to memorize the properties somehow, because you will need them in the future. Select the disks that your RAID is going to include, click “Next,” then “Apply” to save the configuration, and “Yes” to confirm the action. It starts the process of building the RAID system. It’s going to take quite a long time, but in fact the array can be used already: all you need is to make some changes in the Disk Management tool.
05:51 - Meanwhile, the manufacturer’s utility can be used to look up array properties and status, remove it or rebuild it. How to replace a faulty disk RAID 6 is designed to remain operable even if two of its disks get out of order. After one or two disks fail, the array becomes degraded, and while the computer is booting, you will see a message like this. Before taking any action, you should back up all important information, because virtually anything may happen during the array rebuilding process: one more disk may fail, the process may freeze, or there might be a hardware issue - but all of those nasty things can result in a total loss of data. To identify the disk which broke down, use Adaptec Storage Manager.
06:42 - To see which disks are still good, right-click on it and choose Properties. This is where you can find the disk serial number - the same that is printed on the special sticker on the disk case. When the faulty disks are identified, the next step is to replace them with new ones, and add the good disks to the array. Connect new disks to the controller, and while the computer is booting after hardware initialization, press the key shortcut Ctrl+A. In the controller menu, open “Array Configuration Utility”, and then “Initialize Drives”.
07:21 - Now you can initialize the disks you have just connected. Press Insert and Enter. Now they should be added to the array: do it by opening the menu “Manage Arrays,” and then press Ctrl+S to access the control page. Use the Space key to select the necessary disks and hit Enter, then click Yes to confirm the action. After that, the process of rebuilding the array begins. From now on, you can boot the server in normal mode and continue your work.
07:58 - A complete rebuild of the array will take quite a long time to accomplish. If more than two disks fail, or the RAID controller breaks down, the array won’t boot, and this is when a specialized data recovery tool, Hetman RAID Recovery, will help you. This program recovers data from non-operational RAID systems or from disks within such systems. The utility reads from the storage system all the information about the controller, the motherboard, or the software used to create a disk array. Our product can rebuild the crashed RAID and it lets you copy all important information from there.
08:33 - How to recover data from a RAID array with a dead controller When the controller fails, you won’t be able to access the information on the disks. When connected directly to the computer, the operating system will ask you to format the disks for further use. In this case, you will either need a controller of the same model (which doesn’t guarantee the success of this operation, though) or a software tool capable of uniting these disks into a RAID system, displaying and restoring your data. To extract the information from the damaged array, connect the hard disks to a Windows computer, and the operating system will display them as RAW (damaged). In the Disk Management you’ll be suggested to initialize them, and if you try to open them in the Explorer – to format them.
09:24 - No matter what, don’t choose anything - this way or another, you are taking the risk to lose all the data for good. Instead, download, install and run Hetman RAID Recovery. In fact, a lot of service information is written to the disks included into a RAID system: what disks make up the array, in what order they are connected to the controller, the RAID type, block size and the procedure of writing blocks, number of disk groups, and the data on the array size. Having collected all the available information from the system and connected disks, the utility displays the automatically built arrays immediately, as soon as the program starts. In most cases, the program manages to restore RAID on the fly and suggests you to analyze the identified partitions and save any available data.
10:32 - Open the Drive Manager tab, and find the line RAID Arrays to select your storage system from the list. Right-click on it and choose Open. Try Fast scan first: if the disk structure is not damaged, this scan type will suffice, and the program will find and display the files. If the Fast scan can’t find the missing data, then go for Full analysis. When it’s over, the program will display the results in the right side of the window. The program has built the RAID without effort and it can now display all the information still available on the disks.
11:56 - In this case, you don’t have to buy a controller of the same model - and as we know, even when you have it, there’s no guarantee you can build the RAID again without losing its information. With Hetman RAID Recovery, we managed to extract all the data stored in this disk array. Recovering data in a case of dead controller and two hard disks Now let’s simulate a situation, when both the controller and two (!) of the hard disks failed. If one of the disks fails in this RAID type, the array remains completely operable, but when things get from bad to worse and the controller is out of order, there is nothing you can do without specialized software tools. Hetman RAID Recovery detects the RAID type automatically, and displays all the information available about this array.
12:56 - To view the disk contents, right-click on it and select Open. At first, select Fast scan. The program has found all the files that have been written to the array. To have them restored, select the necessary files and click Recovery, specify where to save the information, and click Recovery again. When the process is over, you will find the recovered files in the folder you have chosen for saving them. Recovering data in a case of dead controller and three hard disks Now let’s create a situation with a dead controller and three (!) disks that failed at the same time.
15:16 - In such case, RAID 6 gets completely out of order; even if the controller can be brought to life again, the information is lost. Replacing the failed hard disks is not going to change anything. All right, we have the remaining three disks connected to the motherboard directly. If you couldn’t identify which disks failed, and which are still healthy, connect all of them. Even in this scenario, Hetman RAID Recovery has detected the RAID type automatically. If your array is not on this list, use RAID Constructor. In our case, the array type was detected automatically in the RAID Constructor. To rebuild the array in manual mode, you will need all the information you have on this damaged RAID system. Previously in this video, I emphasized the importance of memorizing its properties when creating the RAID system. If the program has detected the array type automatically, view the information in the next window to make sure that all the properties were detected correctly.
17:16 - This is the factor that determines how much data can be recovered. If one of the properties is incorrect, change it; if everything is correct, click Add and scan the disk array. In this situation, the program has found the data, but a part of the information is damaged. You can try running Full analysis, and it may help you find even more data which is still intact. Now select the files you want to restore, click Recovery, specify the directory where you’d like to save the data, and click Recovery again.
18:52 - When the process is over, all the information will be placed into the folder you have chosen. Conclusion There is a very little chance that three disks may break down at the same time. However, if a disk within a RAID system gets out of order and is replaced with a new one, it takes a few hours to recover the replaced drive, and even longer, if you have to do that for two disks. If one more disk (or several disks) happen to break down while you’re busy recovering the first faulty disk, you’re bound to lose all your data anyway. Hetman RAID Recovery managed to recover data in spite of the damaged controller and two disks, and it was able to restore a part of the information even when three disks failed.
19:41 - It is a good result, because if more than two disks within such RAID system fail, it typically renders the whole array inoperable and all the data might be gone. That is all for now! Hopefully, this video was useful. Remember to click the Like button and subscribe to our channel. Push the bell button to receive notifications and never miss new videos. Leave comments to ask questions. Thank you for watching. Good luck. .