
- Why Regular Data Recovery Tools Can’t Restore Files from RAID
- Key Information About the NAS TerraMaster U8-522-9400
- 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 TerraMaster 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.
How can data fragmentation impact data availability and potential loss on NAS TerraMaster U8-522-9400 devices?
Data fragmentation can impact data availability and potential loss on NAS TerraMaster U8-522-9400 devices in the following ways:
- Reduced Performance: Fragmentation occurs when files are stored in non-contiguous blocks on the storage device. This can lead to slower read and write speeds, affecting the overall performance of the NAS device. As a result, accessing and retrieving data may take longer, impacting data availability.
- Increased Risk of Data Loss: Fragmentation can increase the risk of data loss. When files are fragmented, it becomes more difficult for the NAS device to locate and retrieve all the necessary fragments to reconstruct the complete file. If any of the fragments are lost or corrupted, it can result in data loss or incomplete files.
- Storage Inefficiency: Fragmentation can also lead to storage inefficiency. When files are fragmented, they occupy more space on the storage device than necessary. This can reduce the available storage capacity and result in wasted disk space, limiting the amount of data that can be stored on the NAS device.
- Difficulty in Data Recovery: In the event of a data loss or system failure, fragmented data can make data recovery more challenging. Fragmented files may be scattered across different areas of the storage device, making it harder to recover and restore the data using traditional recovery methods.
To mitigate the impact of data fragmentation, it is recommended to regularly defragment the NAS device's storage. Defragmentation rearranges the fragmented files, placing them in contiguous blocks, which improves performance, reduces the risk of data loss, and optimizes storage efficiency. Most NAS systems have built-in defragmentation tools or third-party software can be used for this purpose. Additionally, maintaining sufficient free space on the NAS device and organizing files into logical folders can also help reduce fragmentation.
How to Remove Hard Disks from Your NAS and Connect Them to a PC
Although the NAS U8-522-9400 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 TerraMaster U8-522-9400. 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.
How to recover data from a TerraMaster
U8-522-9400 has 8 HDD slots, and it supports the following array types:
- RAID 0;
- RAID 1;
- RAID 5;
- RAID 6;
- RAID 50;
- RAID 60;
- JBOD;
NAS supports:
- Ext2;
- Ext3;
- Ext4;
- Btrfs;
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 TerraMaster U8-522-9400 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 |


Recovering data from a physically damaged NAS device can be challenging and may require professional assistance. In the case of a physically damaged TerraMaster U8-522-9400 device, it is recommended to contact a professional data recovery service. They have specialized tools and expertise to recover data from damaged storage devices. Attempting to recover the data yourself may further damage the device and decrease the chances of successful data recovery.