Server Virtualization is the ability to run multiple servers and applications on fewer physical servers. The time when each physical server was used to run a single application is becoming a thing of the past and IT Departments are delivering much better capabilities with a smaller footprint via virtualization than they were with traditional physical servers.
In traditional IT infrastructure, multiple servers are used for various tasks and operations thus use only 10% of their capacity and computing power. This has been, in most cases, a planned outcome in preparation for scalability (or growth) and handle unexpected resource needs. Virtualization spreads the wealth of power and capacity across multiple virtual servers while allowing for expanded resources to servers as needed. This can save on cost of hardware and implementation.
Server virtualization shares a lot of benefits with Cloud Computing including:
• Utilization of resources
• High Availability for applications
• Reduced maintenance costs
Virtualization is, in fact, software installed on traditional server hardware. This software supports a number of different virtual servers, each with its own operating system and applications. Several physical servers are teamed together in an infrastructure called a Virtual Server Farm. This increases the utilization of the servers and the Return On Investment you have made in hardware and software. However, before beginning the process of virtualizing your server base there are a few considerations that any IT administrator needs to keep in mind.
Compatibility and Power
When virtualizing servers, one of the biggest obstacles that needs to be addressed is making sure that your infrastructure and all its underlying components including CPU, memory, storage, network switches, and server operating systems are compatible and will provide sufficient performance.
Preparation may take a lot of time and require outside assistance from hardware system builders and consultants in order to assure a smooth virtualization process. Any hardware infrastructure considered for virtualization should be modern. If not, you may need to budget new hardware into the project.
Depending upon your needs, virtual servers can add a substantial amount of data traffic to your network. Segregating SAN I/O and communication traffic is crucial. Once the virtualization process is complete, if there are problems it will be difficult to tell whether performance issues are due to network issues or server hardware.
Virtual servers generate a greater load on hard drives than physical servers do. Faster hard drives may be necessary depending on your demands. Many come to realize that certain applications are actually slower when virtualized even if more resources like memory and CPU are available. This is because in virtualization, larger blocks of data receive increased priority which means that smaller blocks or requests (such as SQL queries) have to wait before being processed. A workload analysis should be done before any server is virtualized. This will estimate approximate hardware and network usage needs so you can prepare accordingly.
While virtualization brings reduced maintenance costs, it also requires a working knowledge of the virtualization process from your IT department. Traditional IT training will not suffice as virtualization is the exact opposite in thinking and operation. This means that additional training will be needed for your IT department or outside assistance from consultants with the appropriate training and skillset.
The Servers Must Match
Physical server mismatching is often the largest mistake made when creating a virtualization infrastructure. High Availability is the ability to move a virtual server from one physical server to another within the farm without having to shutdown the virtual server thus lowering downtime. If the physical servers in a farm do not have the same chipset (AMD or Intel), this cannot be accomplished thus reducing the benefits of virtualization.
Physical Server Overload
One of the best advantages of virtual servers is that they can be easily created and migrated from one physical server to another inside the virtual farm. The mistake is often made when IT staff deploy more virtual servers than the physical server farm can handle. This can lead to a loss of performance and lessen the ability to keep all virtual servers up should one physical server fail. Understand the limitations and capacities of your virtual farms so you can avoid this often costly mistake.
Which Server Does What?
A virtual server farm is more complex than a traditional server environment. On average, more virtual servers are used than the old traditional physical server environment had due to the fact that dividing applications across virtual servers reduces maintenance downtime. Losing track of which application is on which virtual server is a definite possibility. Within a physical server infrastructure knowing where all your applications are and the servers running them isn’t as difficult a task. Managing your applications in a virtual environment will require more documentation. The great thing is that once the initial documentation is complete, only minor updates will be necessary.
Physical Versus Virtual Licensing
Licensing compliancy for software and operating systems can vary greatly when migrating from physical servers to virtual servers. It’s best to check with your software vendors before beginning the virtualization process. In some cases, virtualization can be more cost effective in software.
Do I Still Need To Do Backups?
Backups are just as critical for virtual servers as they are for physical servers. The difference is the types of backups and the frequency that they are done. A common mistake is to believe that because the servers are now virtual, they are completely redundant because the hardware is so. A successfully implemented virtual server infrastructure will considerably increase the amount of backups done each day.
Some of these backups are called Snapshots. Snapshots take a “picture” if you will of the state, data, and hardware configuration of the virtual server. Think of snapshots as rollback or restore points for a virtual server. Multiple snapshots can quickly consume storage space so having a snapshot retention policy is crucial. Snapshots are not however, recommended for Windows virtual servers running as Domain Controllers. See http://go.microsoft.com/fwlink/?LinkId=159631 for further details.
Snapshots should also not be considered replacements for nightly, weekly, monthly, and yearly backups. Even though virtual server snapshots provide a convenient way to store different points of system state, data, and configuration, there are some inherent risks of unintended data loss if they are not managed properly. A solid backup solution helps provide data protection that is not provided by snapshots.
The Bottom Line
Virtualization can be a major benefit to your organization. However, depending on the age and type of your existing hardware there could be major costs involved. If you do not have the training and expertise, you may need outside assistance from an IT consulting firm to ensure that you take all the necessary steps and do not make mistakes that could hinder your business. Anticipating the potential mistakes associated with virtualization will help you get the best out of future growth in technology. Remember the old saying, “Poor Planning Produces Poor Results”.