NAS QNAP TVS-471 RAID Arrays: Identifying and Recovering from Mechanical and Logical Failures

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS QNAP TVS-471
• How to Remove Hard Disks from Your NAS and Connect Them to a PC
  • Step-by-Step Data Recovery with Hetman RAID Recovery
  • How to Safely Recover Data from Disk Images
  • Where Are the User’s Files Actually Stored?
  • RAID Recovery Software: Detailed Comparison

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 QNAP 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 specific precautions to take while migrating data between NAS QNAP TVS-471 devices?

Yes, there are some precautions to consider while migrating data between QNAP TVS-471 devices. Here are a few:

1. Backup: Before starting the migration process, it is always recommended to create a backup of your data. This ensures that your data is safe in case of any unexpected issues during the migration.
2. Check compatibility: Ensure that both the source and target QNAP TVS-471 devices are running compatible firmware versions. Check the QNAP website or user manuals for firmware compatibility details.
3. Network stability: Make sure that the network connection between the two devices is stable and reliable. Unstable connections can cause data transfer interruptions or corruption.
4. Synchronize data: Use QNAP's built-in data synchronization tools, such as Qsync or RTRR (Real-Time Remote Replication), to ensure that all data is up to date before starting the migration process.
5. Plan downtime: Depending on the size and amount of data being migrated, there may be some downtime during the migration process. Plan accordingly and inform users about the temporary unavailability of the NAS.
6. Test the migration: Before migrating all the data, it is recommended to perform a test migration with a small subset of data to ensure that the process works as expected and there are no issues.
7. Monitor the migration process: Keep an eye on the migration process, especially if it involves a large amount of data. Monitor the progress and check for any errors or warnings that may require attention.
8. Verify the migrated data: Once the migration is complete, verify the migrated data on the target NAS to ensure that everything has been transferred correctly. Compare file sizes, metadata, and perform random checks on various files.

By following these precautions, you can minimize the risk of data loss or corruption during the migration process between QNAP TVS-471 devices.

How to Remove Hard Disks from Your NAS and Connect Them to a PC

Although the NAS TVS-471 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:

1. 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.

2. 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.

3. Label each hard disk according to its position inside the NAS. The order of the drives is crucial for correct RAID reconstruction.

4. 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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   How to Order Remote Data Recovery

Step-by-Step Data Recovery with Hetman RAID Recovery

This program restores data from damaged RAID arrays and is fully compatible with QNAP TVS-471. 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.

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How to recover data from a QNAP

TVS-471 has 4 HDD slots, and it supports the following array types:

• RAID 6;
• RAID 5;
• RAID 10;
• RAID 0;
• RAID 1;
• JBOD;

NAS supports:

• ZFS;
• EXT4;
• EXT3;
• exFAT;
• FAT32 (External Disk Only);
• NTFS (External Disk Only);
• HFS+ (External Disk Read Only);

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:

1. Ensure you have enough free space to store the image. Its size will typically match the size of the original disk.

2. In the main window, select the target disk and choose Tools - Save Disk. You can also select multiple disks if needed.

3. 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.

   

4. 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 QNAP TVS-471 network-attached storage keeps QTS (QuTS hero) 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