Acting as a network device for storing and sharing files, NAS does not require a full operating system.
Usually, the manufacturer pre-installs some stripped-down OS, in most cases based on Linux or BSD. This embedded OS is very limited and is not commonly used for data recovery.
However, since it defines the format used by the NAS drives, it should not be completely ignored during the procedure.
In addition to influencing which algorithms the data recovery utility can use to recover the missing information, it determines what type of desktop operating system can act as a host during file extraction without exposing them to danger.
Read on to learn more about the basics of NAS architecture and make an informed OS choice.
Basics of NAS Architecture
Like any computing device, a NAS is made up of hardware and software elements. The hardware includes a processor, RAM, and one or more hard drives or solid-state drives housed in the chassis.
This chassis connects to the router using an Ethernet cable. The software part is represented by the operating system.
It manages the network connection and provides access to data through network file-sharing protocols.
Such an OS is much lighter and less resource intensive than a conventional multi-purpose operating system.
As a rule, NAS manufacturers offer ready-made solutions with a built-in custom operating system.
Most of them are based on Linux and use the Ext4, XFS, or Btrfs file system. However, some users prefer to build their own NAS free software using open-source BSD-based NAS operating systems.
NAS devices that consist of multiple member drives combine them into a single logical unit with Linux MD RAID or any vendor-specific RAID implementation such as Drobo BeyondRAID and Synology Hybrid RAID.
NAS Recovery Features
Given the above features, a typical NAS box cannot run full-featured data recovery software and cannot be connected directly to a PC via USB.
To read its data, you need to open the device and remove its disks. After that, they can be connected to the computer and processed using the data recovery utility.
Multi-drive NAS devices require data recovery software with RAID functionality, such as UFS Explorer RAID Recovery.
This software requires minimal user effort, supporting both automatic RAID reconstruction and manual RAID detection.
However, some specific technologies used in certain NAS models may only be supported by UFS Explorer Professional Edition.
Which Host OS Should Be Used For Data Recovery?
As a cross-platform software solution, UFS Explorer can be installed on any of the most popular desktop operating systems: Windows, macOS, and Linux. In theory, each of them is suitable for the role of the main OS when restoring a NAS.
However, the choice should take into account the difficulties and possible dangers associated with this, as well as ways to overcome them.
As mentioned above, most NAS vendors integrate custom versions of Linux into their NAS solutions.
Typically, desktop versions of Linux support the same types of file systems and RAID metadata as Linux-based NAS systems.
That being said, it seems quite logical to choose a compatible host OS for NAS recovery: Linux will recognize the RAID metadata, create (boot) the RAID, mount the file system, and give you immediate access to the data from your NAS.
However, given this compatibility, Linux can perform write operations to the NAS file system that can result in permanent data loss.
For this reason, you must be careful to mount the file system in read-only mode and not in read-write mode.
On the other hand, some NAS retailers are expanding their file systems to increase the speed of the NAS device.
A desktop Linux distribution may not support such extensions and may report file system errors even in read-only mode.
If you run the “fsck” tool or mount the file system in read-write mode, it can permanently destroy your data.
Another danger your files may face is the RAID metadata update caused by the desktop Linux distribution. The Linux kernel and software RAID versions may differ.
If Linux updates the RAID metadata, the new format metadata may not be recognized by the NAS.
This may cause the NAS to automatically rebuild, destroying the current RAID and creating new empty storage with default settings.
In light of the above considerations, if you’re going to use Linux as your primary OS anyway, the safest bet is to work with disk images instead of the original disks.
Modern Mac operating systems cannot read or write to most NAS file systems, but they will likely recognize the RAID structures created by the NAS.
The main downside to using macOS to restore a NAS is that if it detects and recognizes RAID structures, it can update them to the latest version or “supported configuration.”
For example, a RAID 10 can be reset to a simple RAID 0 pair with all mirroring information lost.
Therefore, for data recovery from multi-disk NAS devices under macOS, it is preferable to use disk images to avoid overwriting metadata.
Windows family operating systems do not recognize NAS file systems and their RAID metadata, which eliminates the possibility of implicit corruption of the original data.
When working with a NAS from Windows, you can damage your data only by wrong actions, such as modifying data with special tools or initializing or formatting NAS drives.
If you are not sure what steps to take when recovering data from your NAS, use Windows as the most reliable host OS that will protect your data from unexpected actions of the operating system.
However, some third-party Windows drivers for Linux file systems may corrupt or alter your NAS’s file system.
For this reason, before starting the data recovery process, it is highly recommended to disable all drivers that can perform read-write operations on Linux file systems.
Data Recovery Process
Once you’ve prepared your NAS drives for data recovery and selected the optimal host operating system, you’re ready to begin the process.
Specific storage technologies such as Drobo BeyondRAID and ZFS RAID-Z are covered in separate guides.
Useful guidelines for determining the correct order of NAS drives in an XFS-based device can also be found in XFS NAS: find drive order.
After The Data Is Restored
Once you have completed the data recovery, you can continue to use your NAS. To do this, you must return the drives to the NAS, keeping their original order, and then reboot the device. Violating the correct disk order will cause the normal boot process to fail.
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