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

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

Although NAS TVS-471 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 QNAP TVS-471. 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 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);

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 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.

Comparison of software for RAID recovery