Steps to Extract Data from a RAID Disk if NAS ZyXel NAS520 is Not Powering Up

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS ZyXel NAS520
• 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 ZyXel 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 the number of drives in a NAS ZyXel NAS520 device's RAID array impact data recovery and potential loss?

The number of drives in a NAS ZyXel NAS520 device's RAID array can impact data recovery and potential loss in the following ways:

1. RAID Level: The number of drives determines the RAID level that can be implemented. Different RAID levels offer varying levels of data redundancy and performance. For example, RAID 1 (mirroring) requires a minimum of two drives, while RAID 5 (striping with parity) requires a minimum of three drives. The RAID level chosen affects the ability to recover data in case of drive failure.
2. Data Redundancy: The more drives in the RAID array, the higher the level of data redundancy. With more drives, the RAID array can sustain multiple drive failures without losing data. For example, RAID 5 can tolerate the failure of a single drive, while RAID 6 can withstand the failure of two drives. Having more drives in the array reduces the risk of data loss.
3. Rebuild Time: When a drive fails in a RAID array, the data from the failed drive needs to be rebuilt onto a replacement drive. The larger the RAID array (more drives), the longer it takes to rebuild the array. During this rebuild process, the remaining drives are under increased stress, increasing the risk of additional drive failures. If multiple drives fail during the rebuild, it can lead to data loss.
4. Performance Impact: The number of drives impacts the performance of the RAID array. In general, more drives in the array provide higher performance due to increased data distribution and parallelism. However, adding more drives can also introduce more points of failure and increase the risk of data loss if multiple drives fail simultaneously.
5. Cost: The number of drives in the RAID array affects the cost of the NAS device. More drives mean a higher cost of hardware, as well as increased power consumption and maintenance costs. It is essential to balance the cost with the desired level of data redundancy and performance.

In summary, the number of drives in a ZyXel NAS520 device's RAID array impacts data recovery and potential loss by influencing the RAID level, data redundancy, rebuild time, performance, and cost. It is crucial to choose the appropriate number of drives based on the required level of data protection, performance needs, and budget constraints.

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

Although the NAS NAS520 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 ZyXel NAS520. 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 ZyXel

NAS520 has 2 HDD slots, and it supports the following array types:

• RAID 0;
• RAID 1;
• JBOD;

NAS supports:

• Ext2;
• Ext3;
• Ext4;

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 ZyXel NAS520 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