As recently as two years ago, appliances were being touted as the next big thing to hit the business landscape. Today, although they are not perhaps as popular as some people would have us believe, appliances are becoming an increasingly common sight, due partly to changes in attitude, but perhaps more so to the increasing variety of appliances available.
In simple terms an appliance is a self-contained device intended to offer one or more network services. Appliances come in all shapes and sizes (literally) and offer a variety of services.
Most appliances are now standard rack-mount units, but you can still buy freestanding models, which is a good idea if, like many small organizations, you don't have any racks. Although it is physically possible to just drop a rack down on the top of a desk, it will most likely end up with cooling problems because rack-mounted units are often designed only for use in racks.
In many cases, appliances use special versions of existing operating systems like Linux, Unix, Windows and NetWare. Other appliances use a proprietary OS, though there is increasingly an unwillingness to re-invent the wheel. Existing OS offerings are more than capable of providing all of the services required and have the advantage of making it easier to integrate the appliance into the network. In the case of Windows- and NetWare-based networks, it is normally possible to manage the appliance through Active Directory or Novell Directory services.
Interested in Appliances?
Curious about what an appliance could do for your network? To get you started, we've compiled a brief list of some appliances that could have a place in any business.
- Symantec Firewall/VPN Appliance - A firewall/VPN appliance that offers a range of security related functions.
- Google Search Appliance - Appliance that searches and indexes Web-based content within an organization.
- Celestix GW850 Groupware Appliance - "All-in-One" solution that offers a suite of workgroup applications.
- CipherTrust IronMail - E-mail security appliance that offers spam blocking and virus protection, among other things.
- Sun Cobalt RaQ 550 Server Appliance - Integrated Web Server, e-mail server, FTP that offers a complete Web-based business solution.
One of the most popular appliance types is Network Attached Storage, or NAS. A NAS appliance is a unit normally loaded with hard disks. NAS devices are a classic example of appliances because they tend to be deployed to satisfy a direct need and are normally capable of integrating seamlessly into the network. Like the majority of appliances, NAS devices operate independently of the operating systems used elsewhere on the network, though they are often capable of interfacing with them to utilize the user account database. If the appliance requires user accounts, you should investigate to make sure that appliance/OS connectivity is possible, otherwise it will be necessary to create user accounts directly on the device - a redundant task.
Appliances are an interesting proposition for network and system administrators because they offer a very focused approach to a very specific issue. Although some appliances are basically just PCs in a box, there is an increasing trend toward custom-designed appliances optimized to perform specific tasks. As a result they tend to perform better than a general-purpose server. That said, appliances are not always the best way to go, and like anything else in IT, there are advantages and disadvantages.
Appliances have many advantages, but here are probably the most significant.
It's pretty easy to find someone who will debate this point with you, but it is generally accepted that appliances are more reliable than normal computer systems. There are a few reasons for this, but some are the most obvious: there are fewer parts in an appliance; they only have the parts they need; but it is in terms of software that appliances win hands down over their standard PC counterparts. The OS on an appliance is built for one purpose. They do not have to accommodate the myriad of software options that normal servers do. Again, the appliance is what it is, and that's a double-edged sword. If you want to add a new back-up application to your appliance, it may not be possible. But you also don't have to accommodate the additional complications created by installing new software and three service packs only to find that the second service pack for the back-up software is incompatible with the first operating system service pack and so on. Been there, done that.
Again, it's a point that's open to debate but, generally speaking, appliances are more economical than going out and buying a server, the operating system and the application software to perform a specific task. Also consider that operating costs are typically lower and that appliances tend to occupy less space than normal server systems. From a support perspective, appliances go wrong less often, require less configuration and are simpler to administer than server systems. All of these things can add up to significant savings when taken over a long term.
Having told you some of the good things about appliances, it's only fair that we also point out some of the not so good things.
Perhaps the biggest drawback of an appliance is that it is what it is. Opportunities for expansion are generally limited, and even if there are opportunities for upgrading (like adding storage), you can bet that it will be more difficult to perform than it would be with a normal PC. The growth factor applies more to certain types of appliances than it does others, but consider, for example, a Web server appliance. It might come with X, Y and Z, but when you figure out that you actually need more hard disk space, more power or better fault tolerance you might find that your options are pretty limited. Of course how expandable or upgradeable an appliance will be depends on the type of appliance, the form factor and its configuration.
Appliances are designed to do one thing, or one set of things and that's it. If you decide you need a new function, the appliance is unlikely to be able to accommodate. With a conventional server on the other hand, it's as simple as buying and loading a new application, assuming, of course, that the server is able to handle the additional workload.
Another consideration is that there is no re-purposing with an appliance. If after two years you decide that you no longer want or need the service that an appliance offers, or you decide to move to a new product that is server-based, the old appliance is essentially worthless. Unlike a normal server system, you can't turn the appliance into a departmental server or even start using it one of your branch offices.
Fault Tolerance/Backup and Recovery
Again, this depends on what kind of appliance you are using, but you might find that the fault tolerance and back-up/recovery features are not as good as you would like, and that bringing them in line with your corporate standards might be difficult or even impossible. That said, manufacturers are aware of the need for fault tolerance and backup and are including features such as external high-speed SCSI interfaces or remote copy software functions that allow appliance to be backed up to the server. These consideration are more relevant if you are using an appliance that stores data, rather than one which, for example, provides a wireless network infrastructure, but it's also a very important factor that should be high on your list of considerations.
Is An Appliance Right For You?
To determine whether an appliance has a place in your organization, you first need to decide which functions you are looking for, and whether your existing infrastructure has the capabilities to support them. If it does not, and you find yourself looking at the prospect of buying a new server/OS/application combination, then you should most certainly look into whether an appliance will work for you.