Under one roof

Many organisations are not using their servers to their full capacity. Consolidating your servers is one way to boost your return on investment – and at the same time speed up testing and development.

If you're looking for a way to save money, consolidating your database servers could help – especially if you are paying a per-server or per-instance licence fee. With the trend towards per-CPU licences, it makes sense to ensure that you are making full use of the CPUs you are paying for, rather than having a collection of servers running at 10 per cent capacity all day.

Admin tools are much better than ever before, enabling one database administrator to manage many servers from a single console. This even extends to tools that work across the Internet to administer databases. However, although these tools make admin easier and cheaper, they will only fulfil 90 per cent of your administration requirements; the remaining 10 per cent is where experienced database administrators earn their money.

The chances are that most servers in most organisations are underused for most of the day, but before you rush in and virtualise them, remember that the workload of a server at 10am on a Sunday morning may be very different from that at 4pm on a Friday evening. Calculating an average workload is fine, but don't forget to factor in the end-of-month payroll and the quarterly finance update. And if you operate a more complex environment with clustered servers, consider the additional strain imposed by a failover.

Mixed environments
Most large organisations probably have numerous databases running different database products: SQL Server, Oracle IBM DB2, etc. Few IT managers would choose to deploy products from multiple vendors as it imposes additional support and maintenance costs. Unfortunately, the choice is often made for them: perhaps a third-party product only works on a particular database or a server was acquired during the purchase of another company.

No doubt politics will appear rudely on the scene as departments fight for "their" favourite database in which they have invested time and money becoming certified or otherwise qualified. In reality, few consolidation projects will result in the creation of a homogeneous database vendor environment; instead larger clusters of similar databases will appear, which in itself should make management and administration easier.

The top database products – Oracle, SQL Server, DB2 and Sybase – provide end users with a good set of technically competent features. No single product is likely to emerge as a clear and obvious winner unless the business demands specific features. The emergence of hosted database products such as MySQL allows end users to move their database management into the "cloud". Although it is unlikely that many server consolidation projects would do this, it can provide a very cost-effective database platform. Maybe the availability of at least four very good products makes the consolidation process more difficult as final decisions are made on the slimmest of reasons.

Consolidated assets
SQL Server consolidation has become much easier since Microsoft introduced the concept of multiple instances of SQL Server being able to run on a single physical server. One instance/many databases In the past, administrators may have had a one-for-one matching between SQL Server installations and databases; this was a waste of resources. A better approach is for one instance of SQL Server to run multiple databases. This is especially applicable if the databases need a similar level of security and workload provision.

One physical server/many instances
When multiple instances were first supported by Microsoft SQL Server, there was no hard limit on the number of instances supported on one physical server. Basically, you could have as many as you wanted as long as the server could physically run the instances without falling over owing to lack of memory. SQL Server 2008 has a set number of maximum instances dependent on the version of SQL Server being used. It is 16 for SQL Server 2008 Standard Edition and 50 for the Enterprise and Developer Editions. Running multiple instances of SQL Server on one physical computer can save considerably on management costs. This is also useful if your databases have differing security or manageability requirements as the instances are completed isolated from each other. If there is a problem with one instance, it will not adversely affect any of the others. This method of consolidation is a useful way of saving on SQL Server licence costs as only one licence is required per physical processor, irrespective of the number of instances running at any one time.

Virtualisation
Probably the pinnacle of any SQL Server consolidation project would be the creation of a virtualised server environment. With Microsoft Virtual Server, multiple virtual operating systems can be created on one physical server. If you use Microsoft Windows Server R2 Datacenter Edition and SQL Server 2008 Enterprise Edition, all that is needed is one Windows licence and one SQL Server licence per physical processor; this remains true no matter how many virtual environments are installed on the same physical server. Virtualisation is gaining a lot of interest in both development and production environments. For developers the ability to switch between environments quickly enables rapid testing without the hassle of multiple physical servers. For production teams, virtualisation improves manageability even though the virtual environments are strictly isolated from one another.

Migrating and managing databases
Consolidation projects will ultimately end up with data and databases being moved onto different physical servers. In itself this may appear easy, but it takes a lot of forethought and planning to ensure that data is not lost and that the business continues to function. SQL Server 2008 has tools to support the consolidation of SQL Server 2000 and SQL Server 2005 databases, so moving across older installations is made easier. SQL Server Management Studio can manage SQL Server instances whether they are on single, multiple or virtual servers. It can also manage SQL Server 2000 databases onwards, so making a gradual migration a possibility.

Part of the migration project needs to be dedicated to performance testing and ensuring that the business receives the same or better levels of database support post-migration. The SQL Server 2008 Resource Governor enables resources to be allocated against specific workloads. This is useful if you have consolidated a server that needs additional processing capabilities at certain times of the week or year. Scale-up of consolidated servers can be expanded further by using address windowing extensions, a feature in Windows that enables a 32-bit database to use 64GB of memory. In fact, when installed on the 64-bit release of Windows Server 2008 Enterprise or Datacenter Edition, SQL Server 2008 can use up to 2TB of memory – ideal for a consolidated server.

With increasing demands on IT departments to save money and resources, a carefully planned and executed server consolidation project may be just what your organisation needs. It pays, though, to remember that these are difficult projects and that they may not be suitable for every situation you face.