RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple disk drive components into a single logical unit. RAID allows data to be distributed across multiple drives to provide increased storage capacity, reliability and performance compared to a single drive. According to Merriam-Webster, RAID is defined as “an arrangement of multiple hard drives that makes use of techniques such as disk striping (spreading data across multiple drives) and disk mirroring (duplicating data on separate drives) to achieve performance, capacity, or reliability goals.”
The key benefits of RAID include:
- Increased storage capacity – Combining multiple drives creates larger storage pools.
- Speed – Spreading data across multiple disks (striping) allows faster read/write times.
- Redundancy – If one disk fails, the RAID keeps functioning using parity information on the remaining disks.
Some downsides of RAID include cost, complexity, and reduced write performance on some RAID levels. RAID levels range from RAID 0 (striping without redundancy) to RAID 1+0 or 10 (mirroring combined with striping). Higher RAID levels provide increased fault tolerance but are more complex to configure.
Common causes of RAID failure
There are several common causes that can lead to RAID failure and data loss. Some of the most prevalent causes include:
Hardware failure
Hardware components such as hard drives, controllers, cables, and power supplies can fail at any time leading to RAID failure. According to InterData Recovery, failure of the RAID controller is one of the top causes of RAID failures. If the controller fails, the RAID array will become inaccessible.
Data corruption
Data corruption due to things like power outages, power surges, or driver issues can lead to inconsistencies in the data stored across the RAID drives. This can cause the RAID to fail, especially if critical metadata becomes corrupted.DataRecovery.com notes data deletion and malware as common causes of data corruption issues.
Accidental reconfiguration
Accidentally reconfiguring or deleting the RAID configuration can essentially “destroy” the RAID array and make the data inaccessible. This is easy to do if the administrator is inexperienced with managing RAID systems.
Signs your RAID is failing
There are several indications that your RAID array may be failing or experiencing issues. Being aware of these signs can help you catch problems early and take action before complete failure occurs.
One sign is errors on boot. If you see error messages related to the RAID array when starting up your computer, such as “Degraded array” or “Disk failure,” that indicates an issue with one or more of the drives in the array.
Inaccessible data is another red flag. You may find that you are suddenly unable to access files and folders stored on the RAID drives, or experience frequent read/write errors when trying to open or save data. This suggests that the array is having trouble reliably storing and retrieving information.
Slow performance can also be an early warning of impending failure. As more drive errors accumulate, the remaining healthy drives have to work harder to compensate, leading to progressively slower operation. Long wait times for file transfers, program launches, and boot ups are all possible symptoms.
Other signs can include frequent Blue Screen of Death (BSOD) crashes mentioning the RAID controller, detection of bad sectors during scans, and abnormal noises from the hard drives. Overall, any unusual behavior points to issues with the reliability and health of the array.
Back up your data
Backing up your data is one of the most important steps to take before attempting to recover a failed RAID array. Having a recent backup ensures you can restore your files and avoid permanent data loss if the RAID recovery is unsuccessful. There are a few recommended backup solutions:
Cloud backups like Backblaze and Carbonite offer unlimited storage for a monthly fee, automatically backing up your files offsite. This protects against local disasters like hardware failure or theft.
External hard drives provide a local backup you can restore from quickly, but won’t protect against site disasters. Western Digital and Seagate make reliable and affordable external HDD options.
Network attached storage (NAS) devices give local backup storage that can be accessed from multiple devices on your network. Synology and QNAP are leading NAS providers.
Whichever method you choose, be sure to regularly back up important data in multiple places before issues arise. Frequent backups are essential insurance against data loss disasters.
Troubleshoot the RAID
Before attempting recovery, it’s important to troubleshoot the RAID to identify any obvious issues. Here are some steps to take:
Check connections: Make sure all drives in the RAID array are properly seated and connected. Loose cables are a common cause of RAID failures. Reseat all connectors firmly.
Update drivers: Outdated RAID drivers can sometimes cause issues. Update to the latest manufacturer drivers for your RAID controller. Refer to your motherboard or RAID card manufacturer’s website for the most current drivers.
Check RAID config: Use the RAID management software to examine the configuration. Make sure the RAID type, stripe size, drive assignments, and other settings match what you originally configured. Mismatched settings can prevent the RAID from assembling properly.
If you can resolve any obvious issues through troubleshooting, the RAID may start working again on its own. If not, you will need to attempt more advanced recovery methods.
Attempt recovery in RAID software
Before attempting any drastic measures like disassembling the RAID drives or sending them to a professional recovery service, it’s worth trying recovery using software tools. Most RAID controllers have their own software utilities that can detect issues and attempt repairs. For example, LSI and Adaptec RAID cards include MegaRAID Storage Manager and ARCCONF, respectively. These proprietary tools understand the controller’s structure and can rebuild configurations and recover data.
There are also many third party RAID recovery programs that work across various hardware. Some popular options include RAID Recovery Software, DiskInternals RAID Recovery, ReclaiMe Free RAID Recovery, RaidReconstructor, and EaseUS Data Recovery Wizard. These tools can recover from lost or deleted partitions, rebuild arrays, and restore data from failed or degraded RAIDs.
The advantage of software recovery is convenience and non-intrusiveness. However, results vary widely and depend on the health of the drives and extent of damage. If the RAID is severely corrupted or multiple drives failed, software may not suffice. But it’s worth trying before more drastic measures.
Remove and Reassemble RAID Drives
If software recovery methods don’t work, you may need to physically remove the RAID drives and reassemble them into a new array in order to recover data. Here are the steps:
1. Remove all drives from the RAID enclosure and connect each one individually to a PC via SATA/USB adapter. Be sure to label each drive to avoid confusion.
2. Install RAID recovery software like ReclaiMe on the PC and perform an initial scan of each drive.
3. Once scans are complete, use the RAID recovery software to virtually reassemble the drives into a new array based on your original configuration (RAID 0, 1, 5 etc). The software will attempt to rebuild the structure.
4. If the structure rebuild succeeds, the software should be able to read the RAID data and recover your files. Be extremely careful not to write anything back to the drives during this process.
5. Browse through the recovered data and restore any important files you need to another drive. With the files recovered, you can now reformat the RAID drives and reassemble them properly.
Reassembling RAID drives in a new enclosure and letting RAID software rebuild the array is often the best way to recover data without needing an expensive professional service. Just be sure not to make any further changes to the drives until all critical files have been recovered.
Send to data recovery service
When DIY recovery is not possible or has failed, turning to professional data recovery services is the best option to get your RAID data back. Professional services have advanced tools, expertise, and cleanroom facilities to safely recover data from failed RAID devices. This is often the most reliable method of RAID recovery when you’ve exhausted other options.
Data recovery services like Professional RAID Data Recovery Service and Professional RAID Data Recovery Services can retrieve data from RAIDs, even in complex failure situations. They use specialized techniques like chip-off, component replacement, disk imaging, and data extraction to get your RAID functioning again.
The process involves shipping your RAID device to the data recovery lab and letting their engineers take over. Within 1-2 business days, they will diagnose the failure and provide a price quote. After approval, they move forward with data recovery, repairing the RAID if possible, imaging the drives, and extracting your files. Your data will be returned on a fresh external drive. Rates vary based on RAID level and failure complexity.
Professional RAID recovery has high success rates, ensures secure handling of your device, and gets your system working again quickly. When DIY efforts fail, rely on expert services like RAID Data Recovery to salvage your data.
Rebuild the RAID
After troubleshooting the issue, the next step is to rebuild the RAID array. This involves reconfiguring the RAID with new matching drives to restore redundancy and access to your data. Some key steps:
- Choose matching drives – The new drives must match the old ones in terms of capacity, speed, and ideally also manufacturer/model. Refer to your RAID card’s documentation on compatibility.
- Reconfigure RAID – Using the RAID management software or configuration utility, create a new array with the same RAID level and settings. Add the new drives and initiate a rebuild process, which syncs data across drives.
- Monitor rebuild – The rebuild process can take hours or days depending on the size of the array. Monitor progress and do not interrupt it.
- Restore partitions – Once rebuilding is 100% complete, you can restore the original partition layout if needed.
With matching drives installed, the rebuild allows the RAID to be restored without data loss. However, if the original drives had issues, it’s a good idea to run extended read/write testing on the array before putting it back into production.
Restore data and confirm functionality
After rebuilding the RAID array, the next step is to restore your data from your backups. Connect the external hard drive or access the cloud storage where your backups are stored. Copy the files and folders back onto the RAID array.
Once the data is restored, it’s crucial to thoroughly test that the RAID is fully functional again. Reboot the computer and verify the RAID array is detected in the RAID management software. Open files from different locations on the array to confirm all drives are accessible.
Run diagnostics tools like CHKDSK in Windows or fsck in Linux to check for and repair any filesystem errors. Check SMART data to ensure all drives are healthy, with no signs of impending failure.
Monitor the system over an extended period, at least a few days, under normal workloads. Check for any degradation in performance or signs of issues. The RAID should now be restored to complete working order.
For additional reassurance, schedule regular backups going forward. This will ensure you can easily recover data in the unlikely event of another RAID failure down the road.