6.0.1
Table Of Contents
- vSphere Resource Management
- Contents
- About vSphere Resource Management
- Updated Information
- Getting Started with Resource Management
- Configuring Resource Allocation Settings
- CPU Virtualization Basics
- Administering CPU Resources
- Memory Virtualization Basics
- Administering Memory Resources
- View Graphics Information
- Managing Storage I/O Resources
- Managing Resource Pools
- Creating a DRS Cluster
- Using DRS Clusters to Manage Resources
- Creating a Datastore Cluster
- Initial Placement and Ongoing Balancing
- Storage Migration Recommendations
- Create a Datastore Cluster
- Enable and Disable Storage DRS
- Set the Automation Level for Datastore Clusters
- Setting the Aggressiveness Level for Storage DRS
- Datastore Cluster Requirements
- Adding and Removing Datastores from a Datastore Cluster
- Using Datastore Clusters to Manage Storage Resources
- Using NUMA Systems with ESXi
- Advanced Attributes
- Fault Definitions
- Virtual Machine is Pinned
- Virtual Machine not Compatible with any Host
- VM/VM DRS Rule Violated when Moving to another Host
- Host Incompatible with Virtual Machine
- Host has Virtual Machine that Violates VM/VM DRS Rules
- Host has Insufficient Capacity for Virtual Machine
- Host in Incorrect State
- Host has Insufficient Number of Physical CPUs for Virtual Machine
- Host has Insufficient Capacity for Each Virtual Machine CPU
- The Virtual Machine is in vMotion
- No Active Host in Cluster
- Insufficient Resources
- Insufficient Resources to Satisfy Configured Failover Level for HA
- No Compatible Hard Affinity Host
- No Compatible Soft Affinity Host
- Soft Rule Violation Correction Disallowed
- Soft Rule Violation Correction Impact
- DRS Troubleshooting Information
- Cluster Problems
- Load Imbalance on Cluster
- Cluster is Yellow
- Cluster is Red Because of Inconsistent Resource Pool
- Cluster is Red Because Failover Capacity is Violated
- No Hosts are Powered Off When Total Cluster Load is Low
- Hosts are Powered Off When Total Cluster Load is High
- DRS Seldom or Never Performs vMotion Migrations
- Host Problems
- DRS Recommends Host be Powered On to Increase Capacity When Total Cluster Load Is Low
- Total Cluster Load Is High
- Total Cluster Load Is Low
- DRS Does Not Evacuate a Host Requested to Enter Maintenance or Standby Mode
- DRS Does Not Move Any Virtual Machines onto a Host
- DRS Does Not Move Any Virtual Machines from a Host
- Virtual Machine Problems
- Cluster Problems
- Index
Example: Group Power On
The user selects three virtual machines in the same data center for a group power-on attempt. The first two
virtual machines (VM1 and VM2) are in the same DRS cluster (Cluster1), while the third virtual machine
(VM3) is on a standalone host. VM1 is in automatic mode and VM2 is in manual mode. For this scenario, the
user is presented with an initial placement recommendation for Cluster1 (under the Power On
Recommendations tab) which consists of actions for powering on VM1 and VM2. An attempt is made to
power on VM3 automatically and, if successful, it is listed under the Started Power-Ons tab. If this attempt
fails, it is listed under the Failed Power-Ons tab.
Virtual Machine Migration
Although DRS performs initial placements so that load is balanced across the cluster, changes in virtual
machine load and resource availability can cause the cluster to become unbalanced. To correct such
imbalances, DRS generates migration recommendations.
If DRS is enabled on the cluster, load can be distributed more uniformly to reduce the degree of this
imbalance. For example, the three hosts on the left side of the following figure are unbalanced. Assume that
Host 1, Host 2, and Host 3 have identical capacity, and all virtual machines have the same configuration and
load (which includes reservation, if set). However, because Host 1 has six virtual machines, its resources
might be overused while ample resources are available on Host 2 and Host 3. DRS migrates (or recommends
the migration of) virtual machines from Host 1 to Host 2 and Host 3. On the right side of the diagram, the
properly load balanced configuration of the hosts that results appears.
Figure 10‑1. Load Balancing
Host 1
VM1
VM4
VM2 VM3
VM5 VM6
Host 2
VM7
Host 3
VM8 VM9
Host 1
VM1 VM2 VM3
Host 2
VM7 VM4 VM5
Host 3
VM8 VM9 VM6
When a cluster becomes unbalanced, DRS makes recommendations or migrates virtual machines,
depending on the default automation level:
n
If the cluster or any of the virtual machines involved are manual or partially automated, vCenter Server
does not take automatic actions to balance resources. Instead, the Summary page indicates that
migration recommendations are available and the DRS Recommendations page displays
recommendations for changes that make the most efficient use of resources across the cluster.
Chapter 10 Creating a DRS Cluster
VMware, Inc. 65