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
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If the cluster and virtual machines involved are all fully automated, vCenter Server migrates running
virtual machines between hosts as needed to ensure efficient use of cluster resources.
NOTE Even in an automatic migration setup, users can explicitly migrate individual virtual machines,
but vCenter Server might move those virtual machines to other hosts to optimize cluster resources.
By default, automation level is specified for the whole cluster. You can also specify a custom automation
level for individual virtual machines.
DRS Migration Threshold
The DRS migration threshold allows you to specify which recommendations are generated and then applied
(when the virtual machines involved in the recommendation are in fully automated mode) or shown (if in
manual mode). This threshold is also a measure of how much cluster imbalance across host (CPU and
memory) loads is acceptable.
You can move the threshold slider to use one of five settings, ranging from Conservative to Aggressive. The
five migration settings generate recommendations based on their assigned priority level. Each setting you
move the slider to the right allows the inclusion of one more lower level of priority. The Conservative
setting generates only priority-one recommendations (mandatory recommendations), the next level to the
right generates priority-two recommendations and higher, and so on, down to the Aggressive level which
generates priority-five recommendations and higher (that is, all recommendations.)
A priority level for each migration recommendation is computed using the load imbalance metric of the
cluster. This metric is displayed as Current host load standard deviation in the cluster's Summary tab in the
vSphere Web Client. A higher load imbalance leads to higher-priority migration recommendations. For
more information about this metric and how a recommendation priority level is calculated, see the VMware
Knowledge Base article "Calculating the priority level of a VMware DRS migration recommendation."
After a recommendation receives a priority level, this level is compared to the migration threshold you set.
If the priority level is less than or equal to the threshold setting, the recommendation is either applied (if the
relevant virtual machines are in fully automated mode) or displayed to the user for confirmation (if in
manual or partially automated mode.)
Migration Recommendations
If you create a cluster with a default manual or partially automated mode, vCenter Server displays
migration recommendations on the DRS Recommendations page.
The system supplies as many recommendations as necessary to enforce rules and balance the resources of
the cluster. Each recommendation includes the virtual machine to be moved, current (source) host and
destination host, and a reason for the recommendation. The reason can be one of the following:
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Balance average CPU loads or reservations.
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Balance average memory loads or reservations.
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Satisfy resource pool reservations.
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Satisfy an affinity rule.
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Host is entering maintenance mode or standby mode.
NOTE If you are using the vSphere Distributed Power Management (DPM) feature, in addition to migration
recommendations, DRS provides host power state recommendations.
vSphere Resource Management
66 VMware, Inc.