An administrator sets the Failover Capacity for both CPU and Memory at 25%.
Based on the Exhibit below, how much of the cluster’s total CPU resources are still available to power on
additional virtual machines?
A.
45%
B.
25%
C.
70%
D.
60%
Explanation:
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Correct Answer: A
The way that Current Failover Capacity is calculated and used with this admission control policy is shown with an example. Make the following assumptions about a cluster:
■ The cluster is comprised of three hosts, each with a different amount of available CPU and memory resources. The first host (H1) has 9GHz of available CPU resources and 9GB of available memory, while Host 2 (H2) has 9GHz and 6GB and Host 3 (H3) has 6GHz and 6GB.
■ There are five powered-on virtual machines in the cluster with differing CPU and memory requirements. VM1 needs 2GHz of CPU resources and 1GB of memory, while VM2 needs 2GHz and 1GB, VM3 needs 1GHz and 2GB, VM4 needs 1GHz and 1GB, and VM5 needs 1GHz and 1GB.
■ The Configured Failover Capacity is set to 25%.
Admission Control Example with Percentage of Cluster Resources Reserved Policy
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 Configured 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.
Agree, I calculated a different way as in a real exam we don’t have a calculator I think.
CPU-Usage: 75% of 24 = 18 GHz (Available). 7GHz are in use, so we can calculate 18-7 = 11 GHz, which is usable. 11 of 24 GHz is nearly the half, so we can use Answer A.
Thanks for your great solution of this question!
The calculation is as follows as well :
– 25% is reserved for Admission control
– 25% = 1/4.
– 24Ghz/4 = 6 GHz reserved for admission control
– Total amount of CPU frequency in the cluster in 24GHz and 7GHz is already used by the 5 VMs.
This ends to 7+6=13 that is “reserved”. CPU available resource is 24 – 13 = 11, which is around 45% of 24GHz