The Basics of Virtual Network Defragmentation

The Virtual Network

Many modern IT departments view virtual networks as natural extensions of properly configured virtual servers. To further increase efficiency and productivity, virtual servers with multiple virtual machines are set up to share common computer network hardware as a virtual network.
 
A virtual network consists of one or more virtual machines configured to access local or external network resources. The components of a virtual network are a combination of:
  • Network interface cards (NIC), or network adapters
  • Network media (Ethernet)
  • Network storage devices
  • Networks (virtual LANs).
Basically, a virtual network link is one that does not have a physical connection between two machines. The virtual link is implemented using defined network virtualization methods. When a virtual network is created, its structure is dependent upon the configuration and physical hardware of the host operating system. This setup allows for many systems to access multiple network resources.

Virtual Network Storage

As a virtual network datacenter grows, it will need quick, dependable, available, and easily managed virtual storage solutions. The storage technologies for virtual servers include local attached storage, storage area networks (SANs), internet small computer system interface (iSCSI), and network-attached storage (NAS).
 
SANs are an appropriate choice for virtual systems. SANs make use of dedicated network connections to one or many variable-sized disk arrays. These provide virtual servers with a common, shared data access container. SANs provide an optimum storage area that ensures:
  • desired performance
  • ease of failure recovery
  • high availability.

How a Virtual Network Becomes Fragmented

When you constantly modify, add, or delete files on a hard drive, the data is amended discontinuously. Over time, large, numerous gaps appear between files. The scattering of data on your hard disk platters is called fragmentation. This is a main factor of slow, sluggish, unresponsive server performance.
 
Virtual servers are always up and running, handling an immense amount of data. With time, performance suffers due to inevitable disk fragmentation. Applications may start to hang, and the virtual operating system may crash more frequently. The dynamic structure of virtual machines means that fragmentation is also more complicated than on fixed hard disks. As such, defragmentation of your virtual and physical hard drives should be a priority to keep you systems running efficiently.

Defragging a Virtual Network

So what is defragmentation? Defragmentation is a process that reorganizes the files and the empty storage sections into contiguous regions of each, making it faster and easier for the computer to reconstruct the file. This leads to increased retrieval and storage speeds. The impact of disk defragmentation of your virtual and physical hard drives is seen in faster load times, smoother processes and decreased system errors.
 
For optimum virtual machine performance, your virtual machines need to be defragged on a regular basis. Setting up a scheduled task or cron job on each virtual machine can help to ensure this occurs.
 
However, defrag and virtualization can lead to some potential problems. With several virtual machines running on one host, one or more virtual machines may simultaneously trigger unwanted defragmentation, especially during peak times. This could be dangerous, in a business sense, because important resources are pulled away from the other running virtual machines. Server downtime and decreased availability can occur if time and resources are not considered when scheduling defragmentation sessions.

Tips for Defragging a Virtual Machine

To avoid defrag issues with a virtual machine, systems on the virtual network need to undergo specific defragmentation steps. Otherwise, hard drive optimization may not occur.
 
Professional defragmentation software can provide assistance with many of these steps, including:
  • Frequency: Determination of how frequently defragmentation should run in your virtual guest environment based on resource availability at the physical host level.

  • Resource Use: Background processing to ensure virtual machines are completely defragmented, free space consolidated, and drive optimized with no resource contention between each guest virtual machine.

  • System Management: Central management of your entire virtual and physical network and detailed information on fragmentation levels and issues across your network.
Resources
 
Loesgen, B. (2007). Virtual machine best practices. Retrieved March 27, 2009, from the Geeks with Blogs Web site: http://geekswithblogs.net/bloesgen/archive/2007/06/11/113149.aspx.
 
Muller, A., & Wilson, S. (2005). Virtualization with VMware ESX server. Rockland, MA: Syngress.
 
Siebert, E. (2009). Defragmenting virtual machine disk files. Retrieved March 27, 2009, from the IT Knowledge Exchange Web site: http://itknowledgeexchange.techtarget.com/virtualization-pro/defragmenting-virtual-machine-disk-files/.