Thursday, 1 March 2012

VMware DRS - Introduction

What is VMware DRS?
VMware DRS dynamically balances computing capacity across a collection of hardware resources aggregated into logical resource pools, continuously monitoring utilization across resource pools and intelligently allocating available resources among the virtual machines based on pre-defined rules that reflect business needs and changing priorities. When a virtual machine experiences an increased load, VMware DRS automatically allocates additional resources by redistributing virtual machines among the physical servers in the resource pool.
 VMware DRS allows IT organizations to:
  • Prioritize resources to the highest value applications in order to align resources with business goals
  • Optimize hardware utilization automatically and continuously to respond to changing conditions
  • Provide dedicated resources to business units while still profiting from higher hardware utilization through resource pooling
  • Conduct zero-downtime server maintenance
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How Does VMware DRS Work? VMware® DRS aggregates computing capacity across a collection of servers into logical resource pools and intelligently allocates available resources among the virtual machines based on pre-defined rules that reflect business needs and changing priorities.
VMware DRS allows users to define the rules and policies that decide how virtual machines share resources and how these resources are prioritized among multiple virtual machines.
When a virtual machine experiences increased load, VMware DRS first evaluates its priority against the established resource allocation rules and policies, and if justified, allocates additional resources. Resources are allocated to the virtual machine by either migrating it to another server with more available resources or by making more “space” for it on the same server by migrating other virtual machines to different servers. The live migration of virtual machines to different physical servers is executed completely transparent to end-users through VMware VMotion.
VMware DRS can be configured to operate in either automatic or manual mode. In automatic mode, VMware DRS determines the best possible distribution of virtual machines among different physical servers and automatically migrates virtual machines to the most appropriate physical servers. In manual mode, VMware DRS provides a recommendation for optimal placement of virtual machines, and leaves it to the system administrator to decide whether to make the change.
Flexible hierarchical organization of resource pools allows administrators to match available IT resources to the needs of the business organization. Individual business units can receive dedicated IT resources while still benefiting from the efficiency of resource pooling. Robust access privileges make it possible to delegate routine infrastructure tasks for a business unit resource pool to a business unit system administrator.
DRS Automation levels:
  1. Manual – DRS only provides recommendation on placing the VMs. Manual action is required to place them on recommended hosts
  2. Partially automated – During VM power-on, they will be placed on the DRS recommended hosts. VM migrations caused by resource imbalance will be recommended by DRS but won’t be moved automatically
  3. Fully automated – DRS automatically places the VM during power-on also during resource imbalance on the DRS recommended hosts. The migration threshold level can also be set with this level between conservative and aggressive using a slide bar.
What is VMware DPM? VMware Distributed Power Management (DPM) is a pioneering new feature of VMware DRS that continuously monitors resource requirements in a VMware DRS cluster. When resource requirements of the cluster decrease during periods of low usage, VMware DPM consolidates workloads to reduce power consumption by the cluster. When resource requirements of workloads increase during periods of higher usage, VMware DPM brings powered-down hosts back online to ensure service levels are met.
VMware DPM allows IT organizations to:
  • Cut power and cooling costs in the datacenter
  • Automate management of energy efficiency in the datacenter
How Does VMware DPM Work? VMware DPM is a component of VMware DRS that makes recommendations or decisions to power off or power on hosts to save energy. These recommendations are based on a comparison of the available capacity in a DRS cluster against resource requirements of virtual machines plus some administrator defined buffer capacity requirements. If DPM detects there are too many hosts powered on, it will consolidate virtual machines onto fewer hosts and power off the remaining. VMware DPM will bring powered off hosts online once again to meet virtual
machine requirements either at a pre-defined time or when it senses virtual machine requirements increasing.
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Key Features of VMware DRS Intelligent resource allocation. Aggregate disparate hardware resources into unified logical resource pools. With VMware DRS, resource pools are
automatically and intelligently optimized to ensure that IT resource allocation matches business priorities while maximizing hardware utilization.
Flexible hierarchical organization. Organize resource pools hierarchically to match available IT resources to the business organization. VMware DRS ensures that resource utilization is maximized while business units retain control and autonomy of their infrastructure. Resource pools can be flexibly added, removed, or reorganized as business needs or organization change.
Isolation between resource pools. Make allocation changes within a resource pool without impacting other unrelated resource pools. For example, any allocation changes in the resource pool dedicated to a given business unit do not impact other resource pools.
• Access control and delegation. Secure resource allocation at different levels in the company while eliminating bottlenecks. Virtual machine creation and maintenance for a business unit can be delegated to a business unit system administrator thus eliminating reliance on central IT for every routine operation. Management of sets of virtual machines running a distributed application. Optimize the service level of distributed applications by controlling the aggregate allocation of resources for the entire set of virtual machines running the distributed application.
• Manual and automatic mode. VMware DRS collects resource usage information from servers and virtual machines, and then generates recommendations to optimize virtual machine allocation. These recommendations can be executed automatically or manually.

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