There are two types of network-attached storage (NAS)
device: those that come with hard disks already installed, and empty enclosures
in which you install your own disks. Some resellers will install hard disks in
an enclosure for you, but it’s typically cheaper to do it yourself.
Network-attached
storage (NAS)
A pre-assembled NAS device makes sense if you don't have any
spare disks or you want to get up and running as soon as possible, while an
enclosure lets you re-use any disks you may already have. Enclosures with
multiple bays enable you to add extra storage later. Our reviews tell you how
easy each device is to assemble.
If you’re using your NAS device to store office documents
and a few photos, its storage capacity isn't critical. If you want to store an
extensive collection of videos, music and photos, you should buy as much
storage as you can afford. NAS devices fitted with multiple hard disks cost
more than their single-disk counterparts, but they tend to be better value
because they’re cheaper per gigabyte.
If you want to
store an extensive collection of videos, music and photos, you should buy as
much storage as you can afford
Even if you buy a pre-assembled NAS device rather than a DIV
enclosure, you may be able to add more storage. Most models have USB ports to
which you can attach external disks, although some insist on reformatting
external disks, so backing up the data on them is a wise precaution. If you
need vast amounts of storage, buy a NAS device that has several removable disk
trays.
Many NAS devices can configure multiple hard disks as a
Redundant Array of Independent Disks (RAID). This uses two or more disks to
create a single virtual disk that's either quicker or better protected than a
normal hard disk. All the disks in a RAID array should be of the same capacity
- otherwise, you’ll lose capacity on larger disks. Some NAS devices only
support certain RAID types.
Raid 0 joins two or more disks together so that Windows
recognises them as a single volume. In this configuration, an array of two 1TB
disks provides 2TB of storage. Raid 0 is faster than a single disk and other
Raid types, but if one disk fails, you'll lose all your data.
Raid 0 joins two
or more disks together so that Windows recognises them as a single volume.
Raid 1 mirrors the contents of one disk on another so that
your data is safe if a disk fails. It halves the amount of storage available,
though, so a Raid 1 array of two 1TB disks provides only 1TB of storage. Raid 1
arrays require an even number of disks.
If you want to use more than two disks, Raid 5 is usually a
better option. A Raid 5 array requires at least three disks, and spreads parity
(error correction) information across each one, so that the data can be rebuilt
if a disk should fail. The parity information uses up the capacity of a single
hard disk, so a Raid 5 array consisting of four 1TB disks provides 3TB of
storage. Raid 5 arrays also tend to be slower than other Raid types.
Raid 10, also known as Raid 1+0, isn’t usually found in
low-cost NAS devices as it requires at least four disks. It consists of one
RAID 0 array mirrored on another Raid 0 array.
