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Managing the shared processor pool

Managing the shared processor pool

IBM Power Virtual Server located in IBM data centers: Off-premises

IBM Power Virtual Server Private Cloud: On-premises

A shared processor Pool (SPP) is a pool of processor capacity that is shared between a group of virtual server instances (VM).

In SPP, reserved cores can be adjusted based on availability, unlike a VM with a fixed processing capacity.

The following table shows how an SPP is used to reduce the licensing cost when you pay per core:

SPP helps to reduce the licensing cost
Use of SPP VM 1 VM 2 Reserved cores in Pool (User defined) License requirement per core
No Maximum cores = 5
Mode = Dedicated		 Maximum cores = 6
Mode = Dedicated		 NA 5+6 = 11
Yes Maximum cores = 5
Mode = Shared/Uncapped
Entitled capacity = 4.25		 Maximum cores = 6
Mode = Shared/Uncapped
Entitled capacity = 5.25		 Maximum cores = 10 10, Determined by reserved cores in pool

The benefits of using an SPP are as follows:

  • Control licensing costs by limiting the number of processors an uncapped partition can use, reducing the number of software licesnses.
  • A better overall ability to manage processor resources.

Power Virtual Server always has at least one defined SPP as the default pool. You can add up to 63 more SPPs to a single Power Virtual Server host. The SPP is used and shared by a set of VMs of the same machine type (host).

Managing the core-to-virtual core ratio

On-premises

For IBM Power Virtual Server (On-premises), the minimum core-to-virtual core ratio is 1:20. The minimum Entitled Capacity (EC) must be 0.05 and can be incremented by 0.05.

Off-premises

In a Power Virtual Server with Power10, you can provision a VM inside a Shared Processor Pool (SPP) with Virtual Cores (VC) up to 3.0 cores. For any Entitled Capacity (EC) up to 3.0 cores, you can select the ceiling of cores in VC up to 3.0 cores. For EC more than 3.0, VC is rounded off to the next higher integer value. VC is always equal or greater to EC.

For example, the following table shows how your VC is determined based of EC selection:

Example showing core-to-virtual core ratio
User-defined EC value Possible VC value
EC is set to 1.5 VPs can be 2 or 3
EC is set to 2.25 VP is 3
EC is set to 3.5 VPs is 4

Review the following points when you use core-to-virtual core ratio:

  • You can set EC in increments of 0.25.
  • You can set VC in increments of 1.
  • The ratio can only be set on a user-defined SPP.
  • For non-dedicated hosts on Power10, you can set up to 3.0 cores.
  • For Power9 and for virtual machines with entitled capacities greater than 2, the core-to-virtual core ratio is 1:1.

You can specify the host affinity and anti-affinity between two or more SPPs with shared processor pool placement groups. For more information, see Configuring shared processor pool placement group.

Pricing for shared processor pool

When using SPP, you pay for the following:

  • SPP reserved cores that use dedicated host.
  • SPP reserved cores that use the shared capped host.
  • VM cores that are deployed into the SPP that use shared uncapped host.

With SPP you can manage CPU cores. Pricing for memory and storage is charged as ususal. The total estimated cost page does not show the SPP reserved cores-related costs because of service-level estimator limitations. For more information about pricing for SPP in IBM Power Virtual Server, see Pricing for Power Virtual Server. For more information about pricing for SPP in IBM Power Virtual Server (On-premises), see FAQ on pricing.

Configuring a shared processor pool

SPP is a separate resource within a Power Virtual Server workspace. You can manage the entire SPP lifecycle with the Power Virtual Server user interface.

The SPP and your Power Virtual Server workspace are linked and thus shared resource pools are not visible from different accounts. You can create one or more SPPs per workspace.

Create an SPP by specifying the following parameters:

  • A unique name
  • Host group or the machine type
  • Number of processors to reserve.

When you define these parameters, a backend process determines the best host for the new SPP.

When the SPP you create is not configured successfully on the host, the SPP will not have any allocated processing cores. These SPPs must be removed manually, as they are not automatically deleted.

Creating a shared processor pool

To create an SPP, complete the following steps:

  1. Go to Shared processor pools in the Power Virtual Server user interface under Compute.

  2. Click Create pool.

  3. In the Create new shared processor pool window, define the following preferences based on your requirements:

    Creating a new SPP fields and descriptions
    Field Description
    Name Enter a name that is unique within your cloud account.
    Use a name of minimum 2 characters and a maximum of 12 characters. Special characters are not allowed except underscore (‘_’).
    Add to a pool placement group Select the checkbox if you want to deploy the SPP directly into an existing pool placement group.
    If the pool has the required affinity relation with other pools, the best practice is to deploy the pool directly into the placement group. You must create the pool placement group first. It prevents the pool from being deployed on a host that does not satisfy the affinity requirements, and having to move it later.
    Select machine type Specify the machine type. For more information about hardware specifications, see S922, and E980 (Data centers other than Dallas and Washington).
    Reserved processing cores[1] Off-premises For Power Virtual Server, the core-to-virtual core ratio is 1:1 by default.
    On-premises For IBM Power Virtual Server (On-premises), the minimum core-to-virtual core ratio is 1:20. The minimum entitled capacity must be 0.05 and can be incremented by 0.05.

  4. Click Create.

Updating or deleting a shared processor pool

To update or delete an SPP, navigate to Compute > Shared processor pools. Then, select the SPP that you want to edit, and click the edit icon. You will receive a notification after the SPP is deleted successfully.

You can update or delete the following details of an existing SPP:

  • Name of the SPP - Follow the same naming conventions that you used while creating an SPP. For more information, see Creating a shared processor pool.
  • Number of cores - You can update the number of reserved cores based on resource availability and allocation.
  • Delete an existing SPP - You can delete any existing SPP. Before deleting, ensure that no VMs exist in the SPP. If VMs are present, it must be deleted or moved with a support ticket.

Managing a VM of a shared processor pool

When you deploy a VM, you can choose an SPP instead of a host. As you cannot move a VM into or out of an SPP, you can deploy a VM directly into an SPP as a best practice. You can also deploy a VM into a server placement group; the selected SPP host must be compatible with the affinity policy of the placement group that you selected.

When you deploy multiple VMs simultaneously, a new server placement group is created automatically.

During any planned maintenance activity or when you want to perform a remote restart operation, ensure that the VMs are linked to an SPP based on your requirements.

Deploying a VM into a shared processor pool

To add VMs to an existing SPP, complete the following steps:

On-premises Use the API and CLI for bulk deployment of VMs in an SPP. However, you cannot provision more than 3 VMs within an SPP in both small and medium pods.

  1. Open the Virtual server instances page in the Power Virtual Server user interface.
  2. Click Create instance.
  3. Complete the input fields under the General tile based on your requirement.
  4. Select the checkbox Add to a Shared processor pool.
  5. Select an existing shared processor pool.
  6. Continue with the process of creating a VM. For more information, see Configuring a Power Virtual Server instance.

Configuring a shared processor pool placement group

You can configure an SPP with the shared processor pool placement group (SPP PG) to control the host in which SPPs are deployed.

SPP PGs are different from server placement groups. They serve the same purpose but cannot combine resource types.

You must define the following parameters to define an SPP PG:

  • A unique name - The SPP PG name must be unique in your cloud instance.
  • Policy - You can set the colocation policy of the SPP PG as the same server (affinity) or a different server (anti-affinity).

The following table explains how the host selection is determined based on the different options of SPP PG policy selection:

Host selection when SPP PG is empty and non-empty
SPP PG Policy Host selection Result
Same server (Affinity) The new SPP is configured on the same host as determined by the existing PG SPP members. The new SPP is automatically added as a member of the PG policy.
Different server (Anti-affinity) Configure the new SPP on a different host than all host identified by all the existing PG members. The new SPP is automatically added as a member of the PG policy.
Host selection when SPP PG is empty and non-empty
SPP PG Policy Host selection Result
Same server (Affinity) A new SPP is configured on a host that is selected based on the backend processing The new SPP is automatically added as a member of the PG policy
Different server (Anti-affinity) A new SPP is configured on a host that is selected based on the backend processing The new SPP is automatically added as a member of the PG policy

Creating a shared processor pool placement group

To create an SPP PG, complete the following steps:

  1. Go to Shared processor pools in the Power Virtual Server user interface under Compute.

  2. Click the Pool placement groups tab.

  3. Click Create group.

  4. In the Create new pool placement group window, enter the following details:

    Create a new SPP PG field description
    Field Description
    Name Enter a name that is unique within your cloud account.
    Use a minimum of 2 characters and a maximum of 12 characters. Special characters are not allowed except underscore (‘_’).
    Policy Same Server (Affinity)
    Different server (Anti-affinity)

  5. Click Create.

You receive a notification when the new SPP PG is created.

Adding a shared processor pool to a placement group

You can add an SPP as a member to an existing SPP PG if the host of the SPP follows the affinity policy of the group. If the PG policy is set to Same server (affinity), all SPPs that are added as a member of the placement group must remain on the same host. If the PG policy is set to Different server (anti-affinity), the SPP is deployed on a different host other than all its group members.

To add an SPP to an existing SPP PG, complete the following steps:

  1. Go to Shared processor pools in the Power Virtual Server user interface under Compute.
  2. Click the Pool placement groups tab.
  3. Select an existing pool placement group to which you want to add an SPP.
  4. Select one of the following options:
Add SPP to an SPP PG: field description
Field Description
Add existing You can choose from existing SPPs.
Create new You can create an SPP from scratch by defining pool name, machine type, and number of cores. For more information, see Create a new SPP

You will receive a notification after the new SPP PG is created.

Deleting a shared processor pool placement group

To delete an SPP PG, complete the following steps:

  1. Go to Shared processor pools in the Power Virtual Server user interface under Compute.
  2. Click the Pool placement groups tab.
  3. Click the SPP PG that you want to delete.
  4. In the details page, click the delete icon.

Deleting a placement group does not delete its members or change the host in which the placement groups are deployed.

  1. The Reserved processing cores are the number of cores that are reserved for processing and must always be a whole number. ↩︎