- 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?
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 Turbo Station TS-251A / TS-251B / TS-251C / TS-251D device's caching policy impact data loss risks?
The caching policy of a NAS device can impact data loss risks in several ways:
- Write caching: NAS devices often use write caching to improve performance by temporarily storing data in memory before writing it to the storage drives. However, if a power failure or system crash occurs before the data is written to the drives, there is a risk of data loss. To mitigate this risk, NAS devices usually have mechanisms like battery backup units or uninterruptible power supplies (UPS) to ensure that cached data is safely written to the drives during such events.
- Read caching: Read caching is used to accelerate data access by storing frequently accessed data in faster cache memory. While read caching does not pose a direct risk of data loss, it can lead to data inconsistency if the cached data becomes outdated or corrupted. To minimize this risk, NAS devices typically employ techniques like cache coherency algorithms to ensure that the cached data remains consistent with the actual data on the drives.
- Cache settings and configurations: The caching policy of a NAS device can also be influenced by various settings and configurations. For example, the size of the cache, the cache algorithm used, and the cache eviction policy can all impact the risk of data loss. Improperly configured caching settings or using inappropriate cache algorithms may increase the likelihood of data loss or corruption.
It is important to carefully configure and manage the caching policy of a NAS device to balance performance improvements with data integrity and reliability. Regularly backing up critical data and ensuring the NAS device has appropriate power backup solutions can further reduce the risks of data loss.
How to take hard disks out of the NAS and connect them to a PC?
Although NAS Turbo Station TS-251A / TS-251B / TS-251C / TS-251D 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:
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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.
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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.
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Make sure to mark each hard disk in accordance with how they were installed inside the NAS.
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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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Restoring data with Hetman RAID Recovery
This program recovers data from damaged RAID arrays and is fully compatible with QNAP Turbo Station TS-251A / TS-251B / TS-251C / TS-251D. 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.
How to recover data from a QNAP
Turbo Station TS-251A / TS-251B / TS-251C / TS-251D has 2 HDD slots, and it supports the following array types:
- RAID 0;
- RAID 1;
- JBOD;
NAS supports:
- EXT4;
- EXT3;
- 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:
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Make sure that you have enough free space to save the image. The image file size usually equals the disk size.
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Select the disk in the main window, and choose from the menu Tools – Save Disk. You can select multiple disks to be saved.
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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.
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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 Turbo Station TS-251A / TS-251B / TS-251C / TS-251D network-attached storage keeps QTS 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
| Product | Operating system | License type | RAID controller support | Supported file systems | Virtual RAID controller support | Data recovery from damaged RAID | File preview |
|---|---|---|---|---|---|---|---|
| Hetman RAID Recovery | Windows | Paid | Yes, over 100 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
| DiskInternals RAID Recovery | Windows | Paid | Yes, over 100 controllers | FAT, NTFS, Ext2/3/4, HFS+ | No | Yes | Yes |
| R-Studio | Windows, Mac, Linux | Paid | Yes, over 200 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
| UFS Explorer RAID Recovery | Windows, Mac, Linux | Paid | Yes, over 1,000 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
| EaseUS Data Recovery | Windows | Paid | Yes, over 20 controllers | FAT, NTFS, Ext2/3/4, HFS+ | No | Yes | Yes |
| ReclaiMe Free RAID Recovery | Windows | Free | Yes, over 100 controllers | FAT, NTFS, Ext2/3/4, HFS+ | Yes | Yes | Yes |
