Conventions

21.3 Overutilization Migration

Overutilization occurs when a hypervisor's resource usage load goes above a defined threshold. Once this occurs, Moab can be configured to migrate any VM's present on the hypervisor to other, less-used hypervisors.

21.3-A Calculations

In terms of values returned by the resource managers, a hypervisor's Utilization Threshold is exceeded (and migrations should occur at the next overcommit migration event) if:

CPULOAD(HV) > VMOCTHRESHOLD(PROC) * CPROC(HV)

or if:

(CMEMORY(HV) - AMEMORY(HV)) / CMEMORY(HV) > VMOCTHRESHOLD(MEM) * CMEMORY(HV)

Moab will calculate the quantity of virtual machines to remove by subtracting the sum of the CPULOAD(VM)'s and/or the (CMEMORY(VM) - AMEMORY(VM))'s from the corresponding processor or memory hypervisor loads until the overcommit condition is improved.

As mentioned in the example in Overcommit Factor and Threshold we see the following from the configuration:

NODECFG[DEFAULT] OVERCOMMIT=PROC:2.0,MEM:2.0

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