Hands on: Network superstores

A look at what Nas is, and the options available to home and business users

Prompted by a number of reader emails, the topic for this month’s Networks Hands On is network attached storage (Nas).

More specifically, I want to cover what Nas is all about and look in some detail at a typical solution designed to be used by home and small business users.

A quick recap
One of the main reasons for setting up any kind of network is the ability to share files, with a file server the traditional way of satisfying this requirement. But because servers are expected to do lots of other things as well – such as host websites and email and database servers – they tend to be complicated and, where Windows is concerned, expensive to deploy.

A Nas appliance, on the other hand, is a server that shares only files, so it can be made simpler and a lot easier to manage. So much so that, in many cases, all you have to do is plug it into the network and switch it on.

At least that’s what you’ll be told. In reality, it’s not always that easy. It depends on which product you buy, with Nas appliances available in a variety of formats, from budget single-disk products costing about £100 up to highly specified and very scalable server platforms costing thousands, for use in corporate datacentres.

The software involved can also vary. Most Nas appliances are based on Linux, but proprietary software may also be employed, and there are Windows-based Nas appliances, too. For the most part, however, the software doesn’t really matter as long as it does the job of sharing files, is quick, reliable and easy to manage.

A small example
I’ve used several Nas servers over the years from various vendors. Currently, however, I have a Buffalo Linkstation Pro (reviewed in PCW, November 2006), not because it’s the best or most complete Nas server, but it does what I want, requires barely any maintenance and didn’t cost a lot of money. As such, it’s a good example.

Moreover, as you can see from the photograph, the Linkstation Pro is small: the tiny box contains a quiet Linux server and a single Sata hard disk. Mine is a 250GB model, selling for about £125, with capacities up to 750GB available. However, bear in mind that the bigger models will cost a lot more (nearly £400 for the 750GB appliance) and for the same price you can find alternatives offering more functionality.

Like other entry-level Nas devices, the Linkstation Pro is easy to get working. I plugged it into the Lan using the cable provided, switched it on and left it to get an IP address automatically from the DHCP server in my internet router. It came with a ready-formatted hard disk with a few preconfigured Windows shares, one containing the documentation and the other an empty public folder for immediate use by anyone on the network.

I had to configure the appliance to be part of my workgroup, as I don’t use Microsoft’s default names and if it were on a Windows domain or Active Directory network, additional setup would be required.

I wanted to change the default admin password, but it’s easy as management is via a browser. The page shows how I configured the Linkstation Pro to be part of my ‘Editorial’ workgroup. It’s not perfect, of course. The web interface is basic and not particularly quick.

Another drawback is the reliance on a single disk. Should the drive fail, all the data on it will be lost, unless backups have been taken. There’s a USB port to which a separate backup disk can be attached. You can take backups to other networked Linkstations and there’s a built-in backup tool complete with scheduler.

Another restriction is that the Buffalo appliance can only be accessed by Windows and Macintosh clients, but that’s not a big problem. As a single disk appliance you can’t add extra disks should you need it, which can be awkward.

Although there are no hard and fast limits, a Nas appliance such as the Linkst ation Pro will quickly run out of steam as more users try to access it. It’s fine on my Lan with two or three users, and could probably be shared by 10, but you wouldn’t want to use one as the main file server on a big company network.

Bigger examples
Fortunately, there are lots of other Nas products on the market, including much more capable appliances designed to be shared by big networks, with more powerful processors and expandable storage arrays. One example is the Buffalo Terastation Pro, which we also reviewed last year (PCW, June 2006), and which can be specified with up to 2TB of shared disk space on four disks configured as a RAID 5 array.

Again, mentioning the Terastation Pro here doesn’t mean we’re recommending it. Iomega is another brand worth checking out, with a similar product range, including home user products and a number of Linux and Windows-based appliances designed for use by big organisations.

Also worth a look is Adaptec, whose Snap Server products extend even further up the scale. Indeed, you’ll find a review of a new highly scalable dual-processor Snap Server in the Business Section, starting on page 107. There are lots of others besides, all much easier to deploy and manage than a general-purpose file server.

The trouble with arrays
One of the emails that prompted this month’s article was from a reader bemoaning the loss of a vital file accidentally deleted from a Nas appliance – something the reader thought he was protected against because the appliance was equipped with a storage array.

It’s crucial to understand that, in most cases, an array only offers protection against hardware failure. If one disk stops working, the array as a whole can still be accessed until the faulty drive is replaced.

Unfortunately, if you delete a file, the fact that it’s stored on an array is of no real significance. And it doesn’t really matter what type of array is involved. Where disks are mirrored, for example, any operation applied to the main disk will be immediately mirrored to its twin. So delete a file and it’s deleted from both the drives. Likewise, on more complicated arrays (where data and error correction information may be striped across several disk spindles), if a file gets deleted it’s usually wiped off the whole array.

Windows doesn’t help either. Delete a file on your local hard disk and it’s first moved to the Recycle Bin, from where it can be recovered later – assuming you haven’t emptied the bin in the meantime. Delete a file on a network share, however, and it’s usually permanently deleted straightaway. It won’t be in your Recycle Bin or the one on the server and no ‘undelete’ utilities will be of help – it’s gone.

There are exceptions. One of the nice things about the Linkstation Pro, for example, is that it can be configured to move any deleted file into a local recycle folder, rather than deleting it right away.

Otherwise, you have to protect data by taking backups. That can be a bit of a chore, so it’s worth looking for Nas appliances and servers with a versioning filesystem or a snapshot facility.

Typically only available on more expensive products, snapshots can be configured to automatically keep a record of any changes made to the filesystem enabling not just deleted files to be quickly recovered but other file changes to be reversed.

DIY Nas
You don’t have to buy a dedicated Nas appliance.If you’ve got an old PC and a few hours to spare, you can build one of your own.

If it has Windows on it then all you have to do is create some shares, but Windows isn’t really designed to be used in this way and you can run into all sorts of issues – and you’re also limited to sharing files with other Windows users.

Linux is a better alternative. Most distributions ship with utilities to allow files to be shared by a variety of clients, including Samba, which is an open source file server application that can share files using the same SMB/CIFS protocols employed by Windows. The latest version of Samba can even act as a domain server on a Windows NT or Active Directory network.

Most Linux distributions also have graphical tools to manage both Samba and other file-sharing software, and there are web-based interfaces, too. However, a fair amount of expertise will be required to get it all working. To avoid that, you might also want to look at ready-configured tools, such as FreeNAS, which I covered in some detail in this column in the December 2006 issue, or Naslite, which Gordon Laing wrote about in the April 2007 Hands On Hardware column.

A complete Nas server based on BSD Unix, FreeNAS is small enough to be downloaded and run from a USB key if you want, with a virtual appliance implementation also available for use with the free VMWare Player utility. It can be used to share files on a variety of networks, not just Windows, and can be configured and managed from a web browser, just like a commercial Nas appliance.