Storage Area Networks

Storage Area Network (SAN) is a separate, independent network of high-speed storage devices.

A storage area network device is a dedicated system that contains disks for storing information. This is unlike a typical computer which has been designed to carry out a number of different functions. As a result, a storage area network enables the servers within a network to be used for running applications and processing data, not for storing large amounts of information.

A storage area network is therefore more powerful than a typical network as the servers do not need to be used to search and provide information to the users, and the capacity of servers does not need to be increased when further storage is required.

A SAN is designed in such a way that the information stored on it can be accessed by all servers via the Local Area Network (*1) and Wide Area Network (*2). This means that all users can access information extremely easily.

Storage area networks typically use a fibre channel (*3), which is a high speed method that storage devices uses to communicate with each other. As a result, storing and retrieving information is extremely fast.

In summary, a storage area network is a completely independent storage system from a company's servers, making the storage generally available across a network.

The future of Storage Area Networks

Storage area networks were developed in order to overcome some of the problems associated with Network Attached Storage (NAS). This is because NAS devices are sometimes difficult to manage and do not have the same storage capacity. An issue with network attached storage is that because of their design, and because of the way in which information is passed across a network, the network can be slow due to the increased amount of traffic that is created by the NAS.

As a result many analysts forecast that storage area networks will become predominant.

However, the issue of storage is complex and the systems available will very much rely upon your organisations' needs, plans for growth and, ultimately, budget.


Alternatives to Storage Area Networks

The main alternative to storage area network is network attached storage.

At first glance, the differences appear to be few but it is imperative that you have a complete understanding of both before making a decision to buy either.

In very simplistic terms, a NAS is less expensive than a SAN.

Storage area networks tend to be better suited to a large organisation with multiple locations and servers. They tend to have a higher performance than a NAS and for a large organisation where a great deal of information is exchanged, this can be critical.

Benefits of storage area networks over network attached storage:

•    SANs tend to be faster than a NAS.
•    SANs offer very good data protection, i.e. it is difficult to access information unless you have the authority to do so.
•    SANs are more resilient, i.e. they are less likely to go wrong.
•    SANs are better when huge amounts of storage are required.

There are large a number of benefits why a storage area network or network attached storage is better suited according to an organisation's requirements, size and technical needs.

Both SAN and NAS have their merits and some would argue that their NAS system is extremely fast and equally secure as a SAN. Both are extremely good solutions but it is advisable to speak to a couple of credible suppliers that have expertise of both.

Why Storage Area Network?

A storage area network is better suited to large organisations and Government bodies that have a disparate network, i.e. where offices are located across the globe or over a geographically widespread area. This means that information is potentially stored across a wide range of servers or other means of storage, and as a result it can be difficult to access information, simply because it is not in a single place. As a result, finding and accessing the right information can be extremely difficult and in many cases, impossible.

Information is generally regarded as an organisation's 'lifeblood'. It is critical because without it most companies would not be able to function. More importantly, it should be seen as a knowledge repository, because it saves people replicating and researching, for example, a project when perhaps someone in the organisation has already created a similar report or a similar level of expertise.

Furthermore, most organisations have a storage requirement as they need to retain documents, files and other types of information that can be accessed by the users of the computer network. A storage area network is designed to separate storage requirements from the organisations' network and application servers. As a result, performance is increased and people are able to access information faster and more easily and as a result, potentially making them more efficient and productive.

What can I expect to gain by implementing a storage area network?

A storage area network is generally better suited to an organisation where there are many hundreds, if not thousands, of users. Implementing a SAN will mean that there is less of an operational overhead in that the organisation's in-house or external IT expertise will not be required to oversee the day to day workings of a SAN environment. If an upgrade or further storage is required, this can be done quickly and relatively inexpensively without impacting the users and their ability to continue working.

Furthermore, existing storage can possibly be used as part of the new SAN thereby further increasing the return on investment. Certainly within a mission critical environment, a SAN system ensures that information is available 100 percent of the time thereby negating risk and loss of revenues in certain environments.

As a result, you should expect lower storage costs, lower maintenance and support costs and potentially negating the need for further server hardware which is generally more expensive.

Benefits of a Storage Area Network

•    A storage area network can be easier to manage than other storage systems. By consolidating information into one easily accessible place, it becomes easier to access information while also making it simple to increase capacity as and when required.

•    Automation of routine tasks. Routine tasks such as a backups can be automated so that administrators do not have to schedule their own time in order to make sure that backups are completed.

•    Increased efficiency. Organisations with a number of locations and data storage locations can maximise the storage according to who needs it rather than where the information is stored. This means that storage can be used more efficiently as resources can be allocated to where they are needed most. The information can be made to appear as if it is in one, single, repository.

•    Storage can be increased easily. It is possible to increase storage without it impacting an organisation's network performance. Often, upgrades can interfere with the network performance or even lead to an element of downtime meaning that upgrades need to be conducted late at night or at weekends.

•    Better performance. Storage devices are purely dedicated to storing information, leaving the servers within a network to be used solely to process information and applications.

•    Speed of access. Storage area networks are specifically designed for one purpose – to provide storage and fast access to this data. As a result, SANs are far faster than typical servers and storage facilities. It is not necessary to purchase a server with a SAN because they are a stand alone system, this can once again potentially reduce your overall storage costs.

•    Data can be passed from one source of storage, e.g. disk and tape, across to a SAN directly rather than across a network. This means that less data is sent across the network and is therefore a more efficient way of using the servers or a network's computing power.

•    Maintenance. Because a SAN works independently of the organisation's servers, it means that if there are server issues or if maintenance is being carried out on the server(s), personnel can still access critical data on the SAN, and independently of the network, i.e. any work carried out will not impact the users of the network.

•    Availability. Because data can be replicated easily, should one server or element of storage fail, the data will still be available to users. This increases the resilience of the network and is especially important in computing environments where data is viewed as 'mission critical'.

•    Better manageability. Because the storage area network can be 'seen' easily, it becomes much easier to manage because other storage systems are hidden by the servers thereby making the visibility of data difficult. This is not the case with a SAN.

•    Management tools. Monitoring tools (*4) can automatically find and fix any faults without the need for specialist technical personnel to be involved. Some can alert the support department that there is a problem. Many systems are even able to remove duplicate information, e.g. a number of copies of the same word document. These duplicates can take up a large amount of storage and as a result can have an expensive overhead.

•    A storage area network can be managed from anywhere using an internet browser. So even if someone is not near the location of a SAN and some work needs to be carried out, as long as they have access to the internet they can make the necessary changes.

•    A SAN can include both disk and tape so it maximises existing technologies and assets. Tapes are often used for backup because they are relatively inexpensive compared to other media. A SAN can also use other technologies such as optical jukeboxes, tape libraries, and disk arrays. These are different types of storage technologies and from a cost perspective it might be useful to use or consolidate existing systems as much as possible.

•    A storage area network can be accessed by different computing environments or operating systems. This means that Mac users and devices operating Linux can still access the full functionality of a SAN.

•    Disaster recovery. All important or critical information stored on an organisation's computer system can be copied in real time to another storage system located at another building. This ensures that if there are any major problems, e.g. fire, flood, etc. users can still access information (albeit at another company's premises), within minutes rather than hours or perhaps days.

•    A storage area network can be used in conjunction with Network Attached Storage. Because a SAN can communicate with a wide variety of storage devices including a NAS, it is extremely flexible and makes the most of existing infrastructure.

Potential pitfalls

There seem to be very few technological pitfalls to a storage area network. The main pitfalls are based around cost. Not because the storage is expensive, but because installing it can be expensive.

It is fair to state that a SAN is best suited to larger organisations or perhaps in exceptional circumstances within a small company, such as where huge amounts of data are stored.

That said, technology development and improvements are constantly being made and prices decrease so you should discuss your requirements with a number of well regarded suppliers.

•    If your organisation has only a few servers then a SAN will probably not be relevant. Organisations with tens or even hundreds of servers are best suited to a storage area network.

•    Your potential SAN supplier should give you a very clear indication of the return on investment, again highlighting that you may not need what could be a very costly decision.

•    If your disaster recovery requirements are relatively simple, then it may be worth looking at other systems.

•    If your organisation has only one or perhaps a few offices, installing a wide area network connection can be expensive and may not be the right system.

Conclusion

A storage area network is an excellent solution but potentially expensive. However, for the right environment and organisation there is probably no better system.

For a comparison between storage area network and network attached storage see alternatives to storage area networks.

At first glance these systems seem very similar and both have their merits and advantages. It should be noted, however, that for smaller organisations with lower storage requirements, network attached storage will suffice. It should also be noted that they complement each other and many organisations use both to their advantage.

The issue of storage technology is highly complex and potential purchasers should be very clear what their current and potential future requirements are before buying anything. Taking advice from a number of potential suppliers will also help you get a better understanding of which technology is a better suited to your company.


Glossary  

*1 LAN – Local Area Network. A LAN is the technology that allows a group of computers to communicate or share information across a small area.

*2 WAN – Wide Area Network. A WAN is the technology that allows computers to communicate across regions, counties and across the world. A WAN is formed by linking several LANs together. The most commonly used WAN is the internet.

*3 Fibre Channel - Fibre channel is a high speed, highly reliable method of communication that allows storage, servers and other devices, to exchange data with each other extremely quickly.

Information provided by Conjungo