6.7

Table Of Contents
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RP2 was created with a reservation of 5GHz. Two virtual machines of 1GHz and 2GHz are powered
on (Reservation Used: 3GHz). 2GHz remains unreserved.
RP3 was created with a reservation of 5GHz. Two virtual machines of 3GHz and 2GHz are powered
on. Even though this resource pool is of type Expandable, no additional 2GHz virtual machine can be
powered on because the parent’s extra resources are already used by RP1.
Overcommitted DRS Clusters
A cluster becomes overcommitted (yellow) when the tree of resource pools and virtual machines is
internally consistent but the cluster does not have the capacity to support all resources reserved by the
child resource pools.
There will always be enough resources to support all running virtual machines because, when a host
becomes unavailable, all its virtual machines become unavailable. A cluster typically turns yellow when
cluster capacity is suddenly reduced, for example, when a host in the cluster becomes unavailable.
VMware recommends that you leave adequate additional cluster resources to avoid your cluster turning
yellow.
Figure 123. Yellow Cluster
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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, 5GVM6, 2G
In this example:
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A cluster with total resources of 12GHz coming from three hosts of 4GHz each.
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Three resource pools reserving a total of 12GHz.
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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.
vSphere Resource Management
VMware, Inc. 89