NAS (Network Attached Storage) devices

Technically, a NAS (Network Attached Storage) unit is a simplified computer dedicated to provide data storage functions over a network.

NAS is a complex unit, containing most of the components found inside a typical PC. A NAS unit has its own processor, memory, network card, and probably other components, managed by its own operating system. This is different from the "dumb" USB enclosure (disk box), based on just one chip. However, a typical NAS unit lacks keyboard and display, and can only be controlled over a network.

NAS appliances range from the small units suitable for a home use to the massive storage farms consisting of hundreds of hard drives.

The NAS unit is controlled by its own operating system. Hence, the type of the filesystem it would use to store the files is typically defined by the NAS vendor. Since some variation of Linux is used in most cases, the filesystem is likely to be a typical Linux ext/2 or ext/3. This is different from the USB enclosure, on which filesystem type is determined by a host system.

A NAS unit may use more than one hard drive to store data. In such a case some sort of RAID is used. The exact RAID parameters are determined by the vendor and vary between NAS models, and even between the production batches. If some RAID failure occurs and RAID parameters are lost, you need to recover these parameters. Such a process is called RAID recovery. For more information, visit the RAID Recovery Guide.

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