
- Why Regular Data Recovery Tools Can’t Restore Files from RAID
- Key Information About the NAS TerraMaster F5-221
- 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 F5-221 devices?
Data fragmentation can have several impacts on data availability and potential loss on NAS TerraMaster F5-221 devices:
- Reduced Performance: Fragmentation occurs when files are divided into smaller pieces and stored in non-contiguous locations on the storage medium. This can result in slower read and write operations, as the device needs to search for and retrieve data from multiple locations.
- Increased Disk Wear: Fragmentation can lead to increased disk wear as the device needs to perform more frequent and scattered read/write operations. This can potentially shorten the lifespan of the hard drives.
- Higher Risk of Data Loss: When data is fragmented, there is a higher risk of data loss. If a single disk fails in a RAID configuration, the data stored on that disk might be spread across multiple locations. This makes it more challenging to recover the data and increases the likelihood of data loss.
- Difficulty in Data Recovery: Fragmented data can make data recovery more complex and time-consuming. In case of data corruption or accidental deletion, the fragmented data might be scattered across different areas of the disk, making it harder to retrieve and restore the lost data.
- Limited Storage Efficiency: Fragmentation can decrease the overall storage efficiency of the NAS device. When files are fragmented, it can lead to wasted disk space due to the allocation of larger clusters or blocks for storing fragmented data.
To mitigate the impact of data fragmentation on NAS TerraMaster F5-221 devices, it is recommended to regularly defragment the hard drives. Defragmentation rearranges the fragmented data, placing it in contiguous blocks on the disk, improving performance and reducing the risk of data loss. Additionally, monitoring the health of the hard drives and implementing a regular backup strategy can help mitigate potential data loss risks.
How to Remove Hard Disks from Your NAS and Connect Them to a PC
Although the NAS F5-221 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 F5-221. 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
F5-221 has 4 HDD slots, and it supports the following array types:
- RAID 0;
- RAID 1;
- RAID 5;
- RAID 6;
- 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 F5-221 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 |


Yes, there are specific recovery methods for NAS TerraMaster F5-221 devices with striped or mirrored data configurations.
Striped Data Configuration:
Mirrored Data Configuration:
- Identify the failed drive: The NAS device should indicate which drive has failed. Replace the failed drive with a new one of the same capacity.
- Rebuild the RAID: The NAS device should have an option to rebuild the RAID array. Follow the manufacturer's instructions to initiate the rebuild process. This will copy the data from the functioning drive to the new drive, restoring the mirrored configuration.
- Data recovery from a failed drive: If the failed drive is not accessible or cannot be rebuilt, you may need to consult a professional data recovery service to recover data from the failed drive.
It is essential to have regular backups of your data to mitigate the risk of data loss in any RAID configuration.