How to Recover Data from RAID 6 Drives – 2 Methods

• Windows’s check disk action: If the disk partition or the files of RAID 6 go unreadable, Windows operating system executes its in-built disk check tool automatically when you reboot your PC. It is especially so when your RAID 6 disk is readable, resulting in data corruption on the RAID disk.
• Corruption of Hard Disk in RAID 6: If any of the arrays of RAID 6 has bad sectors on the hard drive, the particular drive will typically stop working once the two hard drives get failure. You can also get some signs of the hard drive being offline.
• Failed disk space expand actions: When you wish to extend your disk space without any damage to the previous data, there are high chances of data loss. Due to bad sectors and sudden power-offs, you end up in data loss on the expanding process.
• Sudden computer power off: Designed by the combination of hard disks, RAID 6 is a logical array hard drive controlled by a RAID Card. When huge amount of data is stored on RAID Card or the mainframe, sudden power off your computer may not store the information on ROM, resulting in data loss and RAID array failure.
• RAID controller failure: The RAID controller failing due to a defective port or a power surge.
• Corrupt headers due to virus or malware intrusion
• Missing partition by accident or by the drive aging out
• A DDOS (Distributed Denial of Service) attack

• Failed Mount Actions: When you enter or run the mount commands, you cannot mount the file systems.
• The disappearance of Partitions: When the array has bad sectors, the file partition and the content get lost.
• Inaccessibility to the operating system: If the RAID array fails, the hard disk becomes inaccessible and unrecognizable that give errors. You can see messages like “Disk Boot Failure Insert System and Press Enter” and “Operating System not found.”

1. First, identify the problem by using the following command:

2. If you detect any failed or removed drives, you should confirm their status by using this command:

3. Before removing the drive, you need to isolate it from the remaining array. You need to retain its serial number if it is a physical drive. Type the command mentioned below.

4. Then, use the following command to remove the disk from the array:

5. Next, shut down the system and remove the faulty disk. You can skip this step if the disk in question is virtual.
6. You now need to replicate the data from the old disk to a new disk or partition through the sgdisk utility by installing the gdisk package. Use the following command for the same:

7. Launch the sgdisk utility and use the -R augment to replicate the partition from another active disk. Just type the following command and replace ‘sdb’ and ‘sdc’ with the respective disk drives on your system.

8. Here, you need the following command to prevent GUID conflicts between the two discs:

9. Press the Enter key, and you should see a confirmation on the screen that the operation was completed successfully.

10. You can now add it to the RAID 6 array using the below-mentioned command:

11. Now, you can retrieve the data from the parity of the original disk. Use the command below for the same, replacing the drive names where required.

12. Finally, Verify the recovery using the cat /proc/mdstat command. It should give you a report similar to the following image.

• Run a thorough scan of all your drives every weekend or when you're sure there is not enough stress on the servers.
• Keep the server room isolated, clean, and well-ventilated.
• Check the current and voltage on random drives and peripherals every week. It may bring to your notice any power defects for the system.
• Use commands like 'cat /proc/mdstat' and '--detail /dev/md2' regularly to check for faults in your drives and controllers.
• Maintain strict access control and log all server activities in detail.
• Before updating the software, please review the patch notes to ensure that your hardware supports it.
• Develop a contingency plan with spare drives, multiple power sources, and extra hardware to account for any server issues and give you enough time to make repairs.

RAID 6 array can withstand data loss even if two disks or array gets affected, but sometimes hard drive failures result in data loss. To be specific, Intensive rebuild or electrical events, logical failures, accidental file deletion, software errors, and virus damage are the critical factors responsible for data loss in a RAID 6 array.

To implement RAID 6, you need a minimum of 4 drives and a maximum of 32 drives. Whatever the drive count is, the usable drive capacity to ensure data integrity is two arrays.

Yes, RAID 6 Data Recovery isn’t easy as it uses dual parity. To carry out RAID 6 Data Recovery, you will need a specialized tool and advanced knowledge regarding the RAID Data Architecture.

Unfortunately, the answer is no. If it is just a dual-disk failure, data restoration or recovery is possible, whereas, in three or more disk failures, you need to restore the data from previous backup files only.