VMware vSphere vCenter Server 4.0 - Manual (Page 61)

Figure 6-3. Yellow Cluster
X
cluster
Total Capacity: 12G 8G
Reserved Capacity: 12G
Available Capacity: 0G
RP1 (expandable)
Reservation: 4G
Reservation Used: 4G
Unreserved: 0G
RP2
Reservation: 5G
Reservation Used: 3G
Unreserved: 2G
RP3 (expandable)
Reservation: 3G
Reservation Used: 3G
Unreserved: 0G
VM1, 2G
VM7, 0G
VM2, 2G
VM4, 1G
VM3, 3G VM5, 5G VM6, 2G
In this example:
n A cluster with total resources of 12GHz coming from three hosts of 4GHz each.
n Three resource pools reserving a total of 12GHz.
n The total reservation used by the three resource pools combined is 12GHz (4+5+3 GHz). That shows up
as the Reserved Capacity in the cluster.
n One of the 4GHz hosts becomes unavailable, so total resources reduce to 8GHz.
n At the same time, VM4 (1GHz) and VM3 (3GHz), which were running on the host that failed, are no longer
running.
n The cluster is now running virtual machines that require a total of 6GHz. The cluster still has 8GHz
available, which is sufficient to meet virtual machine requirements.
The resource pool reservations of 12GHz can no longer be met, so the cluster is marked as yellow.
Invalid DRS Clusters
A cluster enabled for DRS becomes invalid (red) when the tree is no longer internally consistent, that is, resource
constraints are not observed.
The total amount of resources in the cluster does not affect whether the cluster is red. A cluster can be red,
even if enough resources exist at the root level, if there is an inconsistency at a child level.
You can resolve a red DRS cluster problem either by powering off one or more virtual machines, moving virtual
machines to parts of the tree that have sufficient resources, or editing the resource pool settings in the red part.
Adding resources typically helps only when you are in the yellow state.
Chapter 6 Using DRS Clusters to Manage Resources
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