Dynamically Manage Resources with LiveCapacity

Virtual Iron provides a comprehensive management environment and policy-engine to automate the management of shared processing, storage and networking resources. Resources can be allocated and de-allocated on the fly to applications when needed based on business rules. The unique policy-driven automation capabilities enable rapid reconfiguration, capacity on demand, failover and recovery without any increased administrative overhead. Virtual Iron's management capabilities enable users to:

- Use policies to automatically apply resources when and where needed, so that performance is maintained regardless of usage spikes.

- Respond quickly to changes in capacity demand with automated reconfiguration.

- Create policies for real-time resource allocation and failover using a graphical wizard.

- Automatically maintain application availability and service levels using policies.

- Trigger reconfigurations based on rules that detect exceeded user-set performance thresholds, e.g. add more CPU capacity to a virtual machine when CPU utilization is greater than 90 percent.

- LiveMigrate virtual machines and adjust resource allocations "on-the-fly" without impacting running applications.

- Virtual Iron's LiveCapacity is a new technology that will automatically move virtual machines around your pool of hosts in the Virtual Data Center to their optimal destination based on a set of user defined rules by utilizing LiveMigrate technology.

In this article we will provide an overview of the technology and allow you to make informed decision on benefits LiveCapacity can provide for your business.

Virtual Iron's LiveCapacity is one of the fundamentally enabling technologies in Virtual Iron 3.1 that removes hardware dependencies and allows physical hardware to be treated as a shared pool of resources to run virtual machines on. It allows maximum possible hardware utilization, dynamically allocating hardware from the user definable pools and automatically maintains application availability and service level agreements. New capacity can be dynamically added to the Virtual Data Center resource pools and the virtual machines can then take immediate advantage of the new hardware resources.

There are some basic configurations options in Virtual Iron's LiveCapacity. The user adds or removes hosts that are to be part of the LiveCapacity pool and specifies the desired performance level for all the hosts in the resource pool.

LiveCapacity Pools

LiveCapacity is set-up as nested pools within the Virtual Data Center pools. These pools span multiple host resources and virtual machines can use resources from the pool they exist in.

How does LiveCapacity figure out where to place virtual machines?

Figuring out candidate hosts for receiving a virtual machine from another host is based on capturing real-time performance data coming from the entire resource pool and then the resource utilization load is computed. Attempts are then made to place live virtual machines on hosts below the pool utilization load average, first using a "best fit" approach and -- if no such hosts are available -- then virtual machines are place in order of increasing load.

Candidate virtual machines for migration off of the host are determined by it's time-averaged tick fraction (fraction of ticks the virtual machine is receiving on the host in need of capacity balancing). This value is used to estimate the impact the virtual machine has on the host.

Once the candidate hosts and virtual machines are determined, the algorithm goes through the list of virtual machines and attempts to atomically LiveMigrates them. The LiveMigrates are only attempted if the host meets the required criteria to run the virtual machine (memory, SAN, etc) and if placing the virtual machine on the host would leave additional capacity below the specified utilization threshold.

LiveCapacity balancing is re-evaluated every few minutes based on real-time performance data collected over that period across the whole resource pool. A balancing re-evaluation is also done when the pool settings change; this includes physical resource or virtual machine assignments.

Virtual Iron's LiveCapacity is free and is a part of Virtual Iron 3.1 Enterprise Edition for multi-server environments that you can download and try free for 30 days.