RAID Array Recovery on NAS Thecus N16000V: Best Practices When It Breaks

Contents

• Why can’t ordinary software tools restore files from RAID?
• How to take hard disks out of the NAS and connect them to a PC?
  • Restoring data with Hetman RAID Recovery
  • Safe recovery from disk images
  • Where are user’s files stored?
  • Comparison of software for RAID recovery

Why can’t ordinary software tools restore files from RAID?

Conventional hard disks keep user’s data by writing it to their surface in a consecutive way, and this is how an entire file is stored on a single hard disk. However, when data is written to a RAID system, a file is divided into several parts. Then these parts are written consecutively to all hard disks within such array. The size of such parts may range from 2 KB to 2 MB, so each file is stored on several hard disks at the same time.

Such approach helps to speed up read and write operations, and it is evident that saving two parts of a file having the size of 1 GB to two hard disks simultaneously is much faster than saving the same 1 GB of data to one hard disk. However, this peculiarity makes file recovery more complicated.

Various RAID levels store information in different ways. Additionally, manufacturers like Thecus also introduce some modifications to this process, and that is why data can be written to hard disk in a wide variety of ways.

How can a NAS Thecus N16000V device's caching policy impact data loss risks?

The caching policy of a NAS (Network Attached Storage) device like Thecus N16000V can have an impact on data loss risks in the following ways:

1. Write Caching: Write caching is a feature that allows the NAS device to temporarily store write operations in cache memory before writing them to the actual storage disks. While write caching can improve performance, it also introduces a risk of data loss in case of power failure or system crash before the data is written to the disks. If the caching policy prioritizes performance over data integrity, the risk of data loss increases.
2. Read Caching: Read caching involves storing frequently accessed data in cache memory to speed up subsequent read operations. While read caching can significantly improve performance, it can also introduce a risk of data loss if the cached data becomes outdated or corrupted. If the caching policy does not prioritize data consistency and integrity, there is a higher risk of data loss.
3. Cache Synchronization: In a multi-node or clustered NAS environment, where multiple NAS devices are connected and share data, cache synchronization becomes crucial. If the caching policy does not ensure proper synchronization of cached data across all nodes, there is a risk of data inconsistency and potential data loss when accessing data from different nodes.
4. Cache Failure: Caches, whether write or read, can fail due to various reasons such as hardware issues or software errors. If the caching policy does not have proper mechanisms to handle cache failures, it can lead to data loss or corruption.

To mitigate data loss risks associated with caching policies, it is important to consider the following:

• Choose a caching policy that balances performance and data integrity based on your specific needs. Some NAS devices offer configurable caching policies, allowing you to adjust the balance according to your requirements.
• Implement mechanisms like battery backup units (BBUs) or uninterruptible power supplies (UPS) to ensure that cached data is not lost in case of power failures.
• Regularly monitor and test the cache functionality to identify any potential issues or failures.
• Implement cache synchronization mechanisms in multi-node or clustered NAS environments to ensure data consistency across all nodes.
• Regularly backup your data to an external storage device or off-site location to mitigate the impact of data loss in case of cache failures or other unforeseen circumstances.

How to take hard disks out of the NAS and connect them to a PC?

Although NAS N16000V can be accessed over the network, you still need to take the hard disks out of the storage device and connect them to a Windows computer. Only in this case will the software be able to scan them properly. Here is what you should do:

1. Turn off the storage and disconnect it from the power supply.

   WARNING! Before you start taking hard disks out of your NAS device, read the manual carefully. Incorrect actions may damage your network-attached storage and/or the hard disks within the RAID system.

2. Take the hard disks out of the NAS one by one, carefully removing them from their slots. Remember that the disks are extremely vulnerable: hitting or dropping them may result in serious physical damage.

3. Make sure to mark each hard disk in accordance with how they were installed inside the NAS.

4. Remove the hard disks and connect them to the computer. In this video, we have explored what ports are used to connect hard disks, and what to do if there are not enough ports or connectors.

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   How to Order Remote Data Recovery

Restoring data with Hetman RAID Recovery

This program recovers data from damaged RAID arrays and is fully compatible with Thecus N16000V. The hard disks that make up the RAID contain technical information about the algorithm used to save files. When launched, Hetman RAID Recovery reads this information and puts the damaged array together. Then you can open the disk and save your files. Also, you can recover the files accidentally deleted from the network drive.

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How to recover data from a Thecus

N16000V has 16 HDD slots, and it supports the following array types:

• RAID 0;
• RAID 1;
• RAID 5;
• RAID 6;
• RAID 50;
• RAID 60;
• RAID 10;
• JBOD;

NAS supports:

• EXT3;
• EXT4;
• XFS;

Safe recovery from disk images

This utility lets you save an entire copy of the disk to file and then work with this image instead of the actual disk. Such feature helps to protect data on the disk from:

• Overwriting during the recovery process;
• Loss resulting from bad sectors;
• User mistakes.

To create an image, do the following:

1. Make sure that you have enough free space to save the image. The image file size usually equals the disk size.

2. Select the disk in the main window, and choose from the menu Tools – Save Disk. You can select multiple disks to be saved.

3. When the image creation wizard starts, you can choose to save the entire disk or select only a part of it. Specify the parameters and click Next.

   

4. At this stage, you need to choose a directory where to save the image. Choose any disk connected to this PC, or save the image by FTP.

   

Where are user’s files stored?

The Thecus N16000V 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.

Comparison of software for RAID recovery