
- Why Regular Data Recovery Tools Can’t Restore Files from RAID
- Key Information About the NAS WD My Book Thunderbolt Duo
- How to Remove Hard Disks from Your NAS and Connect Them to a PC
Why Regular Data Recovery Tools Can’t Restore Files from RAID
Conventional hard drives store user data by writing it sequentially across the disk surface, which means an entire file is typically located on a single drive. In contrast, when data is written to a RAID array, each file is split into multiple fragments. These fragments are then distributed and written in sequence across all the drives in the array. Depending on the configuration, fragment sizes can range from 2 KB to 2 MB, so every file is physically stored across several disks at once.
This approach significantly increases read and write performance — after all, writing two halves of a 1 GB file to two drives simultaneously is much faster than writing the full 1 GB to a single disk. However, this same mechanism makes file recovery far more complex.
Different RAID levels use different methods to distribute and protect data. On top of that, manufacturers like WD often add their own proprietary structures and variations. As a result, data can be written to disks in many different formats, and each requires a specific approach during recovery.
Are there any known limitations or issues related to specific NAS WD My Book Thunderbolt Duo device models that can lead to data loss?
There have been reports of data loss and drive failures with certain models of the WD My Book Thunderbolt Duo. Some users have experienced issues with the RAID controller failing, resulting in data becoming inaccessible or lost. Additionally, there have been reports of the device not being recognized by the computer or experiencing intermittent disconnections. It is always recommended to regularly back up important data to mitigate the risk of data loss.
How to Remove Hard Disks from Your NAS and Connect Them to a PC
Although the NAS My Book Thunderbolt Duo can be accessed over the network, you still need to remove its hard disks and connect them directly to a Windows PC. Only then can the recovery software properly scan and analyze the drives. Follow these steps:
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Power off the NAS and disconnect it from the power source.
WARNING! Before removing any drives, carefully read the device manual. Improper actions may damage both the NAS enclosure and the hard disks in the RAID array.
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Remove the hard disks one by one, gently sliding each drive out of its slot. Remember that hard disks are highly sensitive: any impact or drop can cause serious physical damage.
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Label each hard disk according to its position inside the NAS. The order of the drives is crucial for correct RAID reconstruction.
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Connect the drives to your computer. In this video, we explain which ports you can use to connect hard disks and what to do if your PC does not have enough free connectors.
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Step-by-Step Data Recovery with Hetman RAID Recovery

This program restores data from damaged RAID arrays and is fully compatible with WD My Book Thunderbolt Duo. Each hard disk in the array contains technical metadata describing how files were written. When launched, Hetman RAID Recovery analyzes this metadata, automatically reconstructs the damaged array, and provides access to its contents. After that, you can browse the recovered disk and save your files. The program can also restore files that were accidentally deleted from the network drive.
My Book Thunderbolt Duo has 2 HDD slots, and it supports the following array types:
- RAID 0;
- RAID 1;
- JBOD;
NAS supports:
- Ext2;
- Ext3;
- Ext4;
- HFS+;
How to Safely Recover Data from Disk Images
This utility allows you to create a complete copy of a disk and work with the disk image instead of the physical drive. This approach helps protect your data from:
- Overwriting during the recovery process;
- Additional data loss caused by bad sectors;
- User errors.
To create a disk image, follow these steps:
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Ensure you have enough free space to store the image. Its size will typically match the size of the original disk.
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In the main window, select the target disk and choose Tools - Save Disk. You can also select multiple disks if needed.
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When the Image Creation Wizard opens, select whether you want to save the entire disk or only a specific region. Adjust the settings and click Next.

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Choose the directory where the image will be saved. You may select any available disk connected to your PC or upload the image via FTP.

Where Are the User’s Files Actually Stored?
The WD My Book Thunderbolt Duo network-attached storage keeps OS Linux operating system files on a separate RAID 1 (mirrored) array. Usually, all NAS systems create several volumes on every hard disk, and the first of them takes up to 2 Gb of space. This is where operating system files are stored. Other volumes are united into a RAID array where user’s data is written.
RAID Recovery Software: Detailed Comparison
| Product | Operating system | RAID controller support | Supported file systems | Virtual RAID controller support | Data recovery from damaged RAID | File preview |
|---|---|---|---|---|---|---|
| Hetman RAID Recovery | Windows, Linux, MacOS | Yes, over 100 controllers | FAT, exFAT, NTFS, ReFS, APFS, HFS+, Ext4, Ext3, Ext2, ReiserFS, Btrfs, VMFS, Hikvision, XFS, UFS, ZFS | Yes | Yes | Yes |
| DiskInternals RAID Recovery | Windows | Yes, over 10 controllers | FAT, NTFS, Ext2/3/4, HFS+ | No | Yes | Yes |
| R-Studio | Windows, Mac, Linux | Yes, over 20 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
| UFS Explorer RAID Recovery | Windows, Mac, Linux | Yes, over 100 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
| EaseUS Data Recovery | Windows | Yes, over 20 controllers | FAT, NTFS, Ext2/3/4, HFS+ | No | Yes | Yes |
| ReclaiMe Free RAID Recovery | Windows | Yes, over 100 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |


If the disks in a NAS WD My Book Thunderbolt Duo device have been reformatted, it may still be possible to recover the data, but the success of the recovery will depend on various factors.
When a disk is reformatted, the file system is typically recreated, and the previous file structure and data are erased. However, the actual data may still be present on the disk until it gets overwritten by new data. Therefore, if the disks have been reformatted and no new data has been written to them, there is a higher chance of successful data recovery.
To attempt data recovery, it is recommended to immediately stop using the NAS device and seek professional help from a data recovery specialist or software. They will have the necessary tools and expertise to recover data from reformatted disks. It's important not to attempt any DIY data recovery methods, as they may further damage the data or reduce the chances of successful recovery.
Keep in mind that data recovery can be a complex and time-consuming process, and there is no guarantee of 100% recovery. It's always advisable to regularly back up important data to avoid the risk of data loss.