How to recover data from QNAP TVS-671 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 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.

How can a NAS QNAP TVS-671 device's caching policy impact data loss risks?

The caching policy of a NAS (Network Attached Storage) device like QNAP TVS-671 can impact data loss risks in the following ways:

1. Write caching: NAS devices often use write caching to improve performance by temporarily storing data in a cache before writing it to the actual storage medium. However, if a power outage or system failure occurs before the data is written to the disk, there is a risk of data loss. To mitigate this risk, NAS devices usually have mechanisms like battery backup units (BBUs) or uninterruptible power supplies (UPS) to ensure that cached data is safely written to the disks during such events.
2. Read caching: Read caching involves storing frequently accessed data in a cache to speed up subsequent read operations. While read caching does not directly impact data loss risks, it can potentially lead to data inconsistency issues. If the NAS device experiences a failure or corruption in the underlying storage while relying heavily on read caching, there is a chance that the cached data may not accurately reflect the actual data on the disks. This can result in data loss or data integrity problems if the cached data is used as the primary source.
3. RAID configurations: NAS devices often support various RAID (Redundant Array of Independent Disks) configurations to provide data redundancy and protection against disk failures. The choice of RAID configuration impacts the data loss risks associated with the device. For example, RAID 0 offers high performance but no data redundancy, increasing the risk of data loss if a single disk fails. On the other hand, RAID 1 or RAID 5 configurations provide varying levels of data redundancy, reducing the risk of data loss in case of disk failures.

It is essential to carefully configure and monitor the caching policy and RAID settings of a NAS device to balance performance and data protection. Additionally, regular backups and implementing appropriate disaster recovery strategies can further mitigate data loss risks.

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

Although NAS TVS-671 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-671. 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-671 has 6 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-671 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