6.5.1
Table Of Contents
- vSphere Availability
- Contents
- About vSphere Availability
- Business Continuity and Minimizing Downtime
- Creating and Using vSphere HA Clusters
- Providing Fault Tolerance for Virtual Machines
- vCenter High Availability
- Plan the vCenter HA Deployment
- Configure the Network
- Configure vCenter HA With the Basic Option
- Configure vCenter HA With the Advanced Option
- Manage the vCenter HA Configuration
- Set Up SNMP Traps
- Set Up Your Environment to Use Custom Certificates
- Manage vCenter HA SSH Keys
- Initiate a vCenter HA Failover
- Edit the vCenter HA Cluster Configuration
- Perform Backup and Restore Operations
- Remove a vCenter HA Configuration
- Reboot All vCenter HA Nodes
- Change the Appliance Environment
- Collecting Support Bundles for a vCenter HA Node
- Troubleshoot Your vCenter HA Environment
- Patching a vCenter High Availability Environment
- Using Microsoft Clustering Service for vCenter Server on Windows High Availability
- Index
Figure 2‑1. Admission Control Example with Percentage of Cluster Resources Reserved Policy
total resource requirements
7GHz, 6GB
total host resources
24GHz, 21GB
2GHz
1GB
2GHz
1GB
1GHz
2GB
1GHz
1GB
1GHz
1GB
VM1
9GHz
9GB
H1
9GHz
6GB
H2
6GHz
6GB
H3
VM2 VM3 VM4 VM5
The total resource requirements for the powered-on virtual machines is 7GHz and 6GB. The total host
resources available for virtual machines is 24GHz and 21GB. Based on this, the Current CPU Failover
Capacity is 70% ((24GHz - 7GHz)/24GHz). Similarly, the Current Memory Failover Capacity is 71%
((21GB-6GB)/21GB).
Because the cluster's Congured Failover Capacity is set to 25%, 45% of the cluster's total CPU resources and
46% of the cluster's memory resources are still available to power on additional virtual machines.
Slot Policy Admission Control
With the slot policy option, vSphere HA admission control ensures that a specied number of hosts can fail
and sucient resources remain in the cluster to fail over all the virtual machines from those hosts.
Using the slot policy, vSphere HA performs admission control in the following way:
1 Calculates the slot size.
A slot is a logical representation of memory and CPU resources. By default, it is sized to satisfy the
requirements for any powered-on virtual machine in the cluster.
2 Determines how many slots each host in the cluster can hold.
3 Determines the Current Failover Capacity of the cluster.
This is the number of hosts that can fail and still leave enough slots to satisfy all of the powered-on
virtual machines.
4 Determines whether the Current Failover Capacity is less than the Congured Failover Capacity
(provided by the user).
If it is, admission control disallows the operation.
N You can set a specic slot size for both CPU and memory in the admission control section of the
vSphere HA seings in the vSphere Web Client.
Slot Size Calculation
vSphere HA Slot Size and Admission Control
(hp://link.brightcove.com/services/player/bcpid2296383276001?
bctid=ref:video_vsphere_slot_admission_control)
Chapter 2 Creating and Using vSphere HA Clusters
VMware, Inc. 21