SnapperTalk

Network Attached Storage (NAS) is the new kid on the block when it comes to storage. Previously only used in expensive high-end enterprise-class systems, prices have fallen significantly and technology has advanced, such that it is now in the realm of home or small office use.

As mentioned before, drives with ethernet interfaces, such as NAS devices, are somewhat different than your average firewire or USB hard-drive. It is better to think of them as mini-computers in themselves with a small processor inside providing simple file-sharing capabilities to/from the drive in the same way as sharing a folder or drive on your own computer over the network.

What to look for

RAID: NAS devices may have no RAID at all, or any of the different flavours of RAID. See the different RAID levels on Page 2 for what best suits your needs.

Hot-Swapping: If one drive fails in a RAID setup, you can replace that drive with a new one to restore redundancy to your setup. Usually to do this you would have to power-down the RAID system to install the new drive. Hot-swappable systems let you do this without powering down the system. If you really need absolute 24/7 availability to your data, then this is something you’d want. But I suspect most photographers could cope with a few hours downtime. Hot-swapping is something available on many RAID boxes, not just NAS ones.

Ethernet interface: It will either be Fast ethernet – 100Mbps or Gigabit Ethernet – 1000Mbps. Gigabit is obviously faster if your network and computers support it, and even if they don’t it’ll still work but just at 100Mbps speeds, so I’d advise getting it if possible as you’re likely to want it in the future. Bear in mind that performance of NAS devices depends HUGELY on many other factors such as the speed of the processor inside the box, how it implements file-sharing etc. So some Gigabit NAS boxes may not actually be much faster than 100Mbps ones, whilst others will be substantially faster.

File-sharing protocols: SMB/CIFS is the most common and will work with all modern operating systems. If you’ve done Windows file-sharing this is what you used, but it is also fully compatible with any machine running MacOSX or Linux. AFP (Apple Filing Protocol) is another type of file-sharing protocol used by MacOSX, and if you have Macs you may want this facility as very occasionally SMB/CIFS can encounter problems with unusual file names in OSX not being translated properly into the NAS’s native filesystem. FTP (File Transfer Protocol) is the same as that used for picture transmission so will already be familiar to many photographers. NFS (Network File System) is a protocol often used by UNIX machines, and I’d guess most photographers wouldn’t have much need for it.

Filesystem: Most NAS boxes run some flavour of Windows (FAT, FAT32) or Linux (ext2, ext3) filesystem, probably the latter. That should be fine for most uses because the NAS box itself is the only device actually reading/writing to the disk. But if the NAS box itself completely died and you wanted to take the bare disks and put them into a different machine, the filesystem used could be important.

Web Control Interface: Most NAS boxes can be configured using either an application running on your computer, or through a web browser. Check that the application is available for your operating system, and which browsers are supported.

Advanced functions:

Because NAS boxes contain their own processors many have advanced functions such as:
-Built-in network backup capability to backup up networked machines to the NAS.
-Built-in ability to backup the NAS to an external drive without a host computer running backup software.
-Built-in FTP servers so that the NAS box can be accessed from the internet (with password protection) e.g. you can make your whole archive available to you at any time from anywhere in the world via a web or FTP interface.

Advantages of NAS over regular USB/Firewire enclosures:

Ethernet, TCP/IP and SMB/CIFS are compatible with virtually every computer out there.
Ethernet cable is cheap and can be used for long runs, usually up to 100m.
A NAS box can sit on your network and provide access to its files to any computer on the network at any time, without needing a machine dedicated to providing file-sharing capability running all the time.
NAS boxes usually have many advanced functions that negate the need to perform these functions on your host computer.

Advantages of regular USB/Firewire enclosures over NAS:

Cheaper.
More mature technology, at least at the consumer-grade level.
You have more low-level access to the actual disks and filesystem, so you can run disk utilities, boot from them, etc.
Faster – Most NAS boxes do not approach the read-write speed of even a single normal hard-drive. Also they slow down significantly when transferring large numbers of very small files, because of the TCP/IP overhead involved per file transaction, though that shouldn’t be much of a problem for image-archiving.

There’s been some good discussion of the advantages/disadvantages of NAS in a photographer context here and here over in the Infrant forums, and in this thread in the RobGalbraith Archiving forum. If you’re looking at getting a NAS these forums are a good place to look in understanding all the ins and outs.

Next page: 6. Roll-your-own NAS/File-server
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