Tutorial: How to Recover Data from RAID 5 with 2 disk failure

The basic questions that come to mind while configuring data storage as RAID are: Does the configuration of RAID Array provides sufficient data redundancy and is it boosting the data performance?  The answer to both the queries is ‘Yes’, and failure of a single drive in an Array may not disrupt data availability. However, considering RAID 5, the situation differs in case of more than one disk failure. The question arises, how to recover data from RAID5 with 2 disk failure?, the sequence of action should be — first to recover the data available on the RAID 5, followed by RAID rebuild with the same configuration, and uploading data on the rebuilt RAID.

What are the factors that cause RAID 5 Disk 2 failure?

1. Failure of multiple drives’ at the same time
2. Re-establishing RAID 5 Array with a failed drive
3. No partition configured on RAID
4. Illogical configuration of RAID Volume
5. Malfunctioning of Raid Controller
6. Unexpected power breakdown
7. Virus or malicious software attack

Note: RAID Controller should not be active after 2 Disk failure, hence before starting recovery, stop performing any further actions and turn off the PC.

Raid 5- 2 Disk failure Recovery

The following options help recover data from RAID 5 after 2 Drive failure:

• From Backup
• Manual method
• Professional RAID data recovery software

Steps to retrieve data from a backup:

1. Verify if the available backup can be restored: Restore the backup to a different location, preferably on a spare drive.
2. Verify the data after restore. If the data is clean and usable, proceed to the next
3. Repair the drives in a RAID In case the drives or disks cannot be repaired, then replace them with new disks. Replacing the drives with previously used drives may again create performance related issues. Such a situation is avoidable by testing the drives for performance and certify them for production.
4. Upload the data on the newly configured RAID.
5. Test the performance of RAID Array

The limitations of recovering data from a backup:

• Restorable data may be in good condition, but the entire process may be time-taking
• Fear of crucial data loss
• Restored data may not be complete or in the original intact form.

Due to several drawbacks of RAID recovery from backup, a better option is to recover data with the help of a manual method or by using a professional data recovery software.

Manual method to recover data from RAID 5 with 2 Disk Failure:

Before starting with manual procedure, organise the software and the hardware. The following things should be in place:

1. An external storage device with an adequate amount of disk space. This device could be a storage device like a Network Attached Storage (NAS) or a Personal Computer (PC)
2. Ensure uninterrupted power supply. Install a UPS with the capacity to support Hard Disk dock, router, backup PC or NAS, and the computer system to perform operations
3. An unused PC to connect failed disks with bootable disks
4. Two working drives to replace the existing drive
5. RAID Array configuration to map the rebuilt array with the original

Note: Recovery should be performed only by Certified Professionals. Ensure that the entire recovery operation is executed in the supervision of these experts.

Steps to recover data by using the manual method:

1. Attach all failed disks to the bootable disk
2. Recover content to the recoverable storage disk
3. Replace the existing disk with working drives
4. Rebuild and configure RAID as a duplicate of the original
5. Transfer the entire data from the bootable disk to the newly built RAID Array

Limitations of recovering data by using the manual method

• Lengthy and time taking process with no surety that the retrieved data is free from corruption
• RAID Array rebuild may not be the replica of the original hence there is the risk of data loss
• Data may get corrupt during transit

Manual method to recover data from RAID 5 with 2 disk failure has many limitations. Using a professional data recovery software such as Stellar Data Recovery Technician helps to recover lost or inaccessible data from RAID 5 2 Disk failure.

Professional Data Recovery Software to recover data from RAID 5:

1. Install and launch Stellar Data Recovery Technician software. Download free trial or buy it here.
2. Select RAID Recovery
3. From the next available screens, select all parameters as available in the original RAID

• Hard Drives in RAID Array
• RAID Parity Order Map
• Probable Start Sectors
• RAID Parameters
• Parity Repetition/Delay
• Stripe/Block Size
• Parity Order/Rotation

Once all factors are confirmed, the software displays the final configuration of RAID 5 Array

4. Confirm configuration of RAID Array as available on RAID Reconstruction screen
5. Once the RAID is built (either by selecting from the given options or software help), the software starts the scanning process for RAID Volumes
6. The software rebuilds and displays the configured RAID volumes. Select the volume and click Show Volume List button
7. Volumes available in the RAID are displayed. Select the disk from which data is to be recovered
8. Click Recover to recover data from the selected drives
9. Select a destination and click Start Saving

The entire data of the selected volume is recovered at the suggested location.