RAID Recovery™
Recovers all types of corrupted RAID arrays
Recovers all types of corrupted RAID arrays
Last updated: Apr 11, 2024

How to Rebuild a Failed RAID array?

RAID storage technology is the go-to storage solution for big data users. It not only provides more storage space but also offers unique benefits depending on the array you choose for your setup. In most cases, especially in big data environments, RAID helps to hasten read and write speeds for quick data processing. Additionally, the data redundancy feature offered by RAID technology allows users to have a failsafe to fall back on in times of crisis.

However, although RAID offers many benefits over single-drive storage setups, it has its own problems and disadvantages. Essentially, if a drive fails in your array, you will have to rebuild the RAID as soon as possible to avoid multiple failed drives, which could result in fatal data loss. Rebuilding a failed RAID is a technical task that requires meticulous carefulness. Therefore, before rebuilding a failed array, you should back up all the drives or even clone them to disk image format. This article clearly explains how you can rebuild your RAID array after it fails.

How to Rebuild Your RAID If It Fails?

The process is referred to as “rebuilding,” but it essentially involves creating a new RAID array. To rebuild a RAID array, you need to first identify the failed disk, purchase a replacement with the same specs and size, and then recreate the RAID array.

But how do you know when your RAID needs a rebuild? You should frequently check the status of your RAID drives; if one disk shows an “offline” status, it means the disk is faulty or has failed, indicating a failed RAID array that needs fixing.

Leaving a failed disk in your RAID array will increase the load on the other disks and cause data inconsistencies. Thus, you should rebuild your array the moment you discover a failed drive. This proactive approach will help prevent further data loss and keep you on the safe side.

Note: RAID rebuild time.

6 Steps to Rebuild a Failed RAID Array

There are six steps to take when rebuilding a RAID array; each step is crucial and should be executed with care. To a professional system admin or IT expert, these steps might not seem daunting.

1. Examine the Array

First, identify the failed disk in the array. If possible, label the drives using a marker or pen—avoid using sharp objects on the drives as physical damage can render the disk inaccessible, preventing data recovery unless you have a backup. Also, inspect the drives for any physical damage. Then, proceed to purchase replacement drive(s). If it was the controller that failed, buy a new controller with the exact same specs and features as the failed one.

2. Connect to a Controller

Connect the drives to an external controller compatible with individual disks. If the controller requires additional configurations, follow the instructions in the user guide that came with it.

3. Recover the RAID Array Parameters

If you don’t remember all the parameters of your RAID, such as the RAID level, drive order, strip size, etc., use RAID Recovery software to retrieve this crucial information. Having this information is necessary for the rebuild; incorrect parameter alignment will result in a failure to synchronize the array.

DiskInternals RAID Recovery software is recommended for retrieving RAID setup information and recovering any lost data from the RAID drives. It is user-friendly and compatible with all Windows editions, including server versions. After recovering any lost data and obtaining the RAID information, proceed to rebuild the array.

4. Rebuild the Failed Array

Use the same RAID setup software that you initially used for creating the array. Launch the software, arrange your RAID disks in the correct order (replacing the failed drive with a new one), and follow the steps for rebuilding the array. Often, a RAID array will automatically rebuild once a new disk is attached, thanks to the fault tolerance feature of RAID technology. For the rebuild to be successful automatically, the new disk must match the old failed one's specifications. If the RAID controller failed, you need the exact same model for the RAID to rebuild itself. If the RAID does not rebuild automatically, you will need to do it manually.

5. Write Data to New Array

Once the RAID is rebuilt, you can safely begin to store new data. Format the newly added drive if necessary, and start saving data as before. If you discover missing files, use RAID Recovery software to initiate a data recovery process.

6. Copy Back Your Data

If you had backed up data from the failed RAID to another storage, after rebuilding the RAID, you can copy the data back. Copying data from a backup storage, whether it’s a cloud backup or an external drive, is straightforward.

Data Recovery Processes by RAID Configuration Type

Different RAID configurations use unique redundancy techniques to preserve data even when a drive fails. Below is an overview of how common RAID configurations handle data recovery.

  • RAID 0 employs a striping technique, distributing data across all connected disks. A single drive failure can lead to total data loss, although professional RAID Recovery solutions may help.
  • RAID 1 uses mirroring for data storage, where data is mirrored across all drives, allowing access to data even if one drive fails. However, it offers limited storage capacity.
  • RAID 5 is popular for its fault tolerance and parity data storage on a separate drive. It can survive a single drive failure, allowing normal operation until the failed disk is replaced.
  • RAID 6 is similar to RAID 5 but adds an extra layer of fault tolerance with double parity drives, supporting single-drive failures with minimal impact.
  • RAID 10 (1+0) combines the properties of RAID 1 and RAID 0, offering fault tolerance and speed. It simplifies data recovery if one drive fails.

What You Should Know

Recovering data from any RAID array typically involves disconnecting the drives and connecting them to a computer with a RAID recovery program installed. For arrays that can withstand single drive failures, simply replace the failed drive with a new one of the same specifications to restore normal operation.


  • Does rebuilding RAID array erase data?

    While a RAID 5 array is being rebuilt, the data remains accessible, though you may experience a drop in performance because of the reconstruction activities. It's crucial to remember that RAID 5 systems are designed to withstand the failure of a single drive without losing any data. Nevertheless, should a second drive fail while the rebuild is underway, there is a risk of data loss.

  • How long does it take to rebuild a RAID 1 array?

    Estimate around 15 minutes for each gigabyte to complete the rebuild process. During this time, system performance may be impacted, and the system remains vulnerable to additional drive failures until the rebuild is fully completed.

  • Can you rebuild RAID 1 without losing data?

    To reconstruct a RAID 1 array without data loss, given that RAID 1 consists of two disks with identical data on each, proceed as follows: In the event of both disks failing, employ a tool like MiniTool Partition Wizard to retrieve the data from the hard drive. Following data recovery, introduce two fresh disks to successfully rebuild the RAID 1 configuration without forfeiting any data.

  • What is a RAID rebuild?

    A key benefit of RAID configurations is their resilience to various types of drive failures, allowing for data recovery. Should you encounter the loss of one or more disks in your array, it's often possible to use the data from the surviving disks to restore the missing information. This recovery procedure is referred to as RAID rebuilding.

Related articles

FREE DOWNLOADVer 6.20, WinBUY NOWFrom $249

Please rate this article.