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NAS fundamentals
Network Attached Storage (NAS) is a complex device typically used for storing large amounts of data access to which is provided via a network. Recently, these devices are gaining more and more popularity because data volume grows every year. Beside the fact that NAS provides data storage in general, it also often gives:
- Improved speed,
- Improved reliability compared to regular hard drives,
- advantages of a centralized storage.
NAS consists of several disks, usually from two to five, but a user sees the disks as one big storage.
Home users often use NASes for data archives or backups.
Inside a NAS, disks are combined using the RAID technology.
The reliability and performance of a NAS depend on the chosen RAID level.
The reliability of a NAS means its ability to survive the failure of one or more disks without data loss.
The most commonly used RAID levels are RAID0 and RAID5. RAID0 gives very good read speed,
but does not provide a fault tolerance, while RAID5 being not that good in terms of write speed,
is considered quite reliable since it can survive one member disk failure.
Like everything else in this world, NASes fail.
There are not that many reasons of failures among which the main ones are:
- a failure of a NAS box,
- a failure of disk(s) in a NAS and the impossibility of rebuild,
- accidental deletion of a wrong file(s).
More information on how to recover data from a NAS you can find on this page.
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