Recovering from Mechanical and Logical Failures in NAS QNAP HS-251+ RAID Arrays: Best Practices

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS QNAP HS-251+
• 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.

How can regular data verification or checksum processes help maintain data integrity on NAS QNAP HS-251+ devices?

Regular data verification or checksum processes can help maintain data integrity on NAS QNAP HS-251+ devices in the following ways:

1. Detecting Data Corruption: By regularly verifying data using checksum processes, any potential data corruption can be detected. This ensures that the data stored on the NAS device remains intact and has not been altered or corrupted.
2. Preventing Silent Data Corruption: Silent data corruption refers to the situation where data gets corrupted without any visible symptoms or error messages. By performing regular data verification, checksum processes can identify such silent data corruption and alert the user to take necessary actions, such as restoring the data from a backup.
3. Ensuring Data Consistency: Data verification processes help ensure that the data stored on the NAS device is consistent and accurate. By comparing the checksum values of the stored data with the expected values, any inconsistencies or discrepancies can be identified and resolved.
4. Identifying Data Transfer Errors: During data transfer between devices or over a network, errors can occur, leading to data corruption. By using checksum processes, the integrity of the transferred data can be verified, ensuring that it has been transferred correctly without any errors.
5. Early Detection of Hardware Issues: Regular data verification processes can also help in identifying potential hardware issues on the NAS device. If checksum errors are consistently detected, it may indicate problems with the storage media or other hardware components, allowing for timely repairs or replacements.

Overall, regular data verification or checksum processes provide an additional layer of protection and assurance for maintaining data integrity on NAS QNAP HS-251+ devices.

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

Although the NAS HS-251+ 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.

   Go to view

   

   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 HS-251+. 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.

Go to view

How to recover data from a QNAP

HS-251+ has 2 HDD slots, and it supports the following array types:

• RAID 1;

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 HS-251+ 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