Placement policies
PowerVC uses placement policies to determine which host to deploy an image to. The placement policies are associated with host groups.
- Striping
- The striping placement policy distributes your virtual machines evenly across all of your hosts. For each deployment, PowerVC determines which hosts have enough processing units and memory to meet the requirements of the virtual machine. Other factors for determining eligible hosts include the storage and network connectivity that are required by the virtual machine. From the group of eligible hosts, PowerVC chooses the host that contains the fewest number of virtual machines and places the virtual machine on that host.
- Packing
- The packing placement policy places virtual machines on a single host until its resources are fully used, and then it moves on to the next host. For each deployment, PowerVC determines which hosts have enough processing units and memory to meet the requirements of the virtual machine. Other factors for determining eligible hosts include the storage and network connectivity that are required by the virtual machine. From the group of eligible hosts, PowerVC chooses the host that contains the most virtual machines and places the virtual machine on that host. After the resources on this host are fully used, PowerVC moves on to the next eligible host that contains the most virtual machines.
- CPU utilization balanced
- This placement policy places virtual machines on the host that has the lowest CPU utilization in the host group. The CPU utilization is computed as a running average over the last 15 minutes.
- Memory utilization balanced
- This placement policy places virtual machines on the host that has the lowest memory utilization
in the host group. The memory utilization is computed as a running average over the last 15 minutes.
- HMC managed hosts do not accurately report their memory utilization. Therefore, host groups that use this policy should not contain HMC managed hosts. If there are any HMC managed hosts in the host group, PowerVC always targets the HMC hosts for placement because their utilization is recorded as 0.
- All virtual machines on a PowerVC host should have RMC running for the most accurate memory utilization estimates.
- CPU allocation balanced
- This placement policy places virtual machines on the host that has the lowest percentage of its
CPU allocated after the deploy or relocation.
For example, consider an environment with two hosts.
- Host 1: Has 16 total processors, 4 of which are assigned to virtual machines.
- Host 2: Has 4 total processors, 2 of which are assigned to virtual machines.
Assume that the user deploys a virtual machine that requires one processor. Host 1 would have (4+1)/16, or 5/16 of its processors allocated. Host 2 would have (2+1)/4, or 3/4 of its processors allocated. Therefore, the virtual machine is scheduled to Host 1.
- Memory allocation balanced
- This placement policy places virtual machines on the host that has the lowest percentage of its
memory that is allocated after a virtual machine deploy or relocation.
For example, consider an environment with two hosts.
- Host 1: Has 16 GB total memory, 4 GB of which is assigned to virtual machines.
- Host 2: Has 4 GB total memory, 2 GB of which is assigned to virtual machines.
Assume that the user deploys a virtual machine that requires 1 GB of total memory. Host 1 would have (4+1)/16, or 5/16 of its memory allocated. Host 2 would have (2+1)/4, or 3/4 of its memory allocated. Therefore, the virtual machine is scheduled to Host 1.