An Introduction to RAID Data Recovery

For many tech savvy people, the word RAID is commonplace. Unfortunately, not everyone in the world who owns and operates a computer knows how to do more than use it. While you may be reading this because you already have some idea of what RAID is, there is still a lot to know about RAID, how it works, and how to successfully recover RAID data if RAID fails.
If your RAID has failed, data recovery is required. If you are wondering how to actually perform RAID data recovery, you will need to read further on in this article series. This article is an introductory guide providing basic information on RAID and its importance.

What is RAID and How Does it Work?

RAID is an acronym for “redundant array of independent disks.” For the non-techie, this describes a volume of drives that function independently from one another, but are all part of a single storage system. This means that data for a single file can be saved across several disks at once; 48 KB of a document saved to the first disk, the next 48 KB of the document saved to the next disk, so on and so forth.
Why is this important? When a single disk fails, your RAID system can piece together the entirety of the missing data using the information stored in the remaining separate disks. You can compare this to finding the last word in a crossword puzzle by using the crossword clue and the letters already present in the row – you create the missing data by using the information stored elsewhere. This is called “fault tolerance.”

What is so Important about RAID?

While personal computers typically do not utilize a RAID configuration for everyday data storage, there are many industries that rely on RAID data storage configurations to keep the data flowing quickly, efficiently and reliably. When using RAID configuration, the data can be accessed faster because the data is stored in smaller amounts across several disks. This allows more read/write requests to the same volume at one time.
RAID configuration also provides more reliable uptime for data servers and networked storage. In most RAID configurations, the volume will continue operating even if one disk fails. This allows the failed disk to be hot swapped out without interrupting service or losing data.  Unfortunately, if a RAID fails — for example, if the wrong disk is removed during service, multiple disks fail or the RAID controller is shutdown improperly — then the entire volume may become unreadable.

When Does RAID Data Recovery Become Necessary?

RAID data recovery becomes necessary when data deletion or catastrophic failure occur. Catastrophic failure can be caused by any number of things from human error to computer viruses to power outages.
As with data recovery from an independent logical disk or partition, undeleting or restoring files that have been lost due to “software” causes—such as corrupted file tables, reformatting, viruses and user error—is fairly straightforward. Data recovery from a functional RAID can be done with any well-designed data recovery utility. But if the RAID configuration has been compromised or there is a hardware failure, the task becomes notably more complex.
There is more detailed information on RAID configurations and data recovery in the articles on this website. This short introductory guide provides the foundational information on RAID and its importance, but further reading on this topic is encouraged, especially if you decide to perform RAID data recovery on your own.

RAID Data Recovery in Several Steps

When a RAID fails, there are certain actions you can take that will make the problem better and other actions you can take that will make the problem worse. In this brief tutorial, we’ll walk through some of the steps that will increase your chances of a successful RAID data recovery.

How RAID Works and Why Recovering Works Differently

Unlike your typical hard drives or other forms of storage, RAID is not just one drive, but instead a series of drives running together in sync. Because of this, you do not have the luxury of knowing all your files are on a single drive, formatted together where they can be found easily in the event of deletion or damage. Instead you have a system that splits files across multiple drives, using an algorithm to decide where to store the bits of each file. To add to the confusion, recovery from simple drives involves easy to use software, while RAID involves a complicated process depending on how your system is set up and to what extent the damage is. While most RAID configurations offer redundancy (excluding RAID 0), the risk of multiple drive failure, system failure, or file deletion is still very apparent, and it’s key to know how to approach the recovery process to maximize your potential for success.

RAID Failure and Data Recovery

A redundant array of independent disks (RAID) can offer increased performance, fault tolerance or both, depending on the RAID level. RAID volumes, however, are still susceptible to failure. Your chances for a successful RAID data recovery depend on the type of RAID failure you experience.

RAID Levels and Data Recovery

A redundant array of independent disks (RAID) is a set of two or more physical disks (such as hard disk drives) that are treated like a single logical disk by the operating system. When compared to a traditional standalone disk, RAIDs pose a number of challenges when it comes to data recovery. Complicating the issue of data recovery from a RAID further are the numerous RAID levels and classifications. Because of these complexities, most techies will caution the everyday user away from attempting a RAID data recovery. In many cases, this advice is valid. Professional data recovery agencies are the best equipped to salvage data from failed RAIDs, but their services come at a very high price (if you have to ask, you can’t afford it).  But if the value of your data falls short of the cost of a professional RAID recovery, you may have more to gain than lose by attempting a do-it-yourself RAID recovery using commercial off-the-shelf software.

Virtual RAID Reconstruction

If performing data recovery on a single failed hard disk drive is delicate work, then RAID data recovery is like brain surgery—one wrong move and you could wipe out gigabytes of precious data. It goes without saying that data recovery from a failed RAID isn’t work well-suited to the reckless. But if you can’t afford to pay a professional data recovery lab, then there are a few do-it-yourself approaches that are less risky. One such RAID data recovery method is to reconstruct the RAID as a virtual device. While not 100% successful, given the right parameters you can often restore some or all of your data with minimal impact to the original disks.

RAID Recovery Software

Professional data recovery in a “clean room” can be extremely costly, ranging into the tens of thousands of dollars for a single RAID. For offices on a budget, you may want to consider using RAID recovery software. Attempting a RAID data recovery using commercially available software isn’t free—but depending on the value of your data, it may be worth the opportunity to recover some or all of your data.