The original purpose of a Network-attached storage (NAS) device was to provide storage for servers. This was done (usually) over an Ethernet/IP network. Many NAS devices still do just that; providing networked storage (via NFS or other protocols) to hosts. However, with extra computing power available these days, many NAS devices can do much more than serve storage over a network. Even a relatively inexpensive NAS can now provide many of the functions that traditionally a server would fulfill.
Notwithstanding the extra functions that a NAS device can perform, the main initial area that is of interest in setting up a NAS is protection of data. Specifically, a customer wants to protect against data loss. There are a few ways to do this. One is to back up data to tape and keep a copy offsite. Second is to use a NAS with RAID capacity to protect against a HDD failure. A NAS that has at least two drives (and most will support at least two) can be set up in a RAID 1 array configuration. RAID 1 is a mirror configuration, so ideally the two disks should be the same size.
Taking a look under the hood, many NAS devices on the market utilise a cut down form of the Linux operating system. If you have grown up using CLIs, then this may be for you. If not, don't fret: NAS devices these days usually have a web type GUI as well.Leaving aside the NAS devices that don't use Linux (there are some), one of the nice things about having a Linux kernel is that you can use Logical Volume Manager (LVM) to set up volumes. If you want to read a little about LVM and how to use it, you can look at my previous posts. If you really want to do some serious, low-level physical device crafting, you can even use the mdadm utility. Figure A shows the output from running vgdisplay -v on a Synology DS213.
Click to enlarge.
As mentioned before, most NAS devices can run different file-sharing utilities. The common ones are SMB, CIFS and NFS. Some NAS devices will also run AFS. The extra file-sharing utilities help when you have a small office with several different types of OS.
DHCP is another feature that is on many NAS devices. Depending on how your network is set up, you can enable this feature or leave it disabled. One point, though. The IP address of the NAS should be fixed if a router is acting as the DHCP server. Otherwise you could have issues with accessing your data.
There are other features that NAS devices offer, including acting as a:
- wireless Access Point
- DNS server
- email gateway
- print server
Finally, many NAS devices offer a backup-to-cloud solution. My preference (however) is to not dispense with an old-fashioned backup-to-tape regime just yet.
When purchasing a NAS, there is one main point to consider. NAS devices don't always come with HDDs installed. The HDDs are usually purchased separately. This means checking that the HDDs are actually compatible with the NAS. Most vendors have online lists of HDDs that are recommended for their NAS.
A final consideration for a NAS is whether to use a model that does both wired and wireless, or to just use wired. Unless you really cannot use wired for some reason, I would pick wired. The main issue with using wireless are the extra security issues involved. Throughput can sometimes be an issue as well.
As you can see by the extensive feature list, a NAS device is far more than a simple place to store data. Many NAS devices now are effectively small servers. All the services traditionally offered by a server can now be performed by a NAS. They can offer a competitive alternative to a server for a SOHO business.
Scott Reeves has worked for Hewlett Packard on HP-UX servers and SANs, and has worked in similar areas in the past at IBM. Currently he works as an independent IT consultant, specializing in Wi-Fi networks and SANs.