How to recover data from Thecus N4520 NAS

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.

Are there any specific system logs or event notifications to monitor for early detection of data loss on NAS Thecus N4520 devices?

Yes, Thecus N4520 devices have several system logs and event notifications that can be monitored for early detection of data loss. Here are some specific logs and notifications to monitor:

1. System Logs: The NAS device maintains system logs that record various events and activities. These logs can provide valuable information about any errors or issues that may lead to data loss. Monitor the system logs regularly for any unusual or critical entries.
2. RAID Status Notifications: The Thecus N4520 supports RAID configurations for data protection. It is essential to monitor the RAID status notifications to ensure the integrity of the RAID array. Any notifications indicating a degraded or failed RAID status should be investigated promptly to prevent data loss.
3. Disk Health Notifications: The NAS device can monitor the health of individual hard drives. It can generate notifications if any disk shows signs of failure or is experiencing errors. Monitoring these notifications can help detect disk failures early, allowing for timely replacement and data recovery.
4. SMART Monitoring: The Thecus N4520 supports SMART (Self-Monitoring, Analysis, and Reporting Technology) for hard drives. SMART attributes provide detailed information about the health and performance of the drives. Regularly monitor the SMART attributes and look for any indications of potential drive failures.
5. File System Check Notifications: The NAS device performs periodic file system checks to ensure the integrity of the stored data. Monitor the notifications related to file system checks to identify any inconsistencies or errors that may lead to data loss.
6. Backup Job Notifications: If you have configured backup jobs on the NAS device, monitor the notifications related to backup job status. Any failures or errors in the backup process can indicate potential data loss if not addressed promptly.

It is recommended to enable email notifications for these events and logs so that you can receive alerts in real-time. Additionally, regularly reviewing the NAS device's management interface or using dedicated monitoring software can help ensure early detection of data loss.

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

Although NAS N4520 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 N4520. 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

N4520 has 4 HDD slots, and it supports the following array types:

• RAID 0;
• RAID 1;
• RAID 5;
• RAID 6;
• 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 N4520 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