Migrating slot-based resource plans to use multidimensional scheduling

Add multidimensional scheduling features to an existing slot-based resource plan, so that you can take advantage of multidimensional resources without manually recreating the plan, or the having a steep learning curve. The migrated plan will not have the full features of a multidimensional resource plan created from scratch; however, if you don't require all the complex features, this updated plan still allows you many of the benefits of multidimensional scheduling. You migrate a plan to multidimensional scheduling using the cluster management console.

Tip: For a complete overview of multidimensional scheduling features, see Multidimensional scheduling.

Depending on the type of policy that is configured for the resource plan, you can create a new multidimensional resource plan, or join an existing multidimensional resource plan.

Considerations before you migrate your plan

Before you migrate a slot-based resource plan to multidimensional scheduling, consider the following information:

A migrated resource plan, fully supports the following multidimensional scheduling resource features:
1. Lender grace periods are honored.
2. Owned resources can be borrowed by any consumer. For owned resources to be shared, you do not require configuring peer to peer lending or borrowing.
3. Resource sharing using multidimensional scheduling (and with this, any existing service to slot ratio configuration no longer require exclusive allocation).
Keep in mind that a migrated plan does not have the full features of a native multidimensional plan. Here are the differences between a migrated plan and a native multidimensional scheduling plan:
- A migrated plan does not support multiple resource groups, with preferences, within one plan.
- A migrated plan does not support consumer-level priority (where high priority consumers always get resources before low priority consumers).
- For resource allocation, in a migrated plan:
  - Best packing resource allocation strategy is not supported.
  - If you migrate slot-based resource plan with exclusive allocation, the migrated resource plan will adopt any allocation-level exclusive allocation configuration.
  - Exclusive consumer-level allocation is supported with both share and hybrid policies.
- There are two sharing models for multidimensional scheduling: priority sharing and proportional sharing. A consumer participates in both sharing models at the same time. Slot-based scheduling, however, does not support the priority sharing model; therefore, resource plans migrated to multidimensional scheduling adopt a default priority value of 5.
- A migrated plan does not support partial ownership of a host for a group of hosts (for example, resource group rg1 can own 40% of each host, resource group rg2 can own 60% of each host).
- A migrated plan does not support consumer-level slot mapping.
The share limits and ownership for the migrated resource plan adopt multidimensional scheduling share limit and ownership rules, as follows:
- Share limits for a multidimensional resource plan are based on the maximum slot allocations in the share pool, including the private share pool and public share pool. For more information about share limits for multidimensional resource plans, see Share pools.
- Ownership for a multidimensional resource plan is based on owned hosts and reserved hosts, and consumer rank. For more information about ownership for multidimensional resource plans, see Ownership policy.
When an overlap of resources exists between multiple resource groups, the slot definition for that resource group is automatically changed to CPU*1 when the resource plan it is associated with is changed to multidimensional scheduling. When you are defining a resource group, ensure that the resources that are used are not being used by another resource group.

Behavior when changing to a new multidimensional resource plan

Behavior for each policy is as follows when you are changing to a new multidimensional resource plan:

Ownership policy

Lending and borrowing resources is simplified for migrated resource plans, as you must configure only the lender's grace period.

Migrated resource plans support defining reserved hosts that are not able to be borrowed or reclaimed.

The migrated resource plan sets the GetFreeFromNextLevelBeforeReclaim parameter to Y to retrieve free resources before resource reclaim happens, as this value is default for a multidimensional resource plan.

Share policy: Slot-based scheduling does not support priority sharing. Therefore, migrated resource plans adopt a default priority value of 5. The share ratio uses the number that is configured in the original slot-based resource plan.
The migrated resource plan sets the EnforceSiblingShareReclaim parameter to Y to maintain the share ratio between sibling consumers, as this value is default for a multidimensional resource plan.

Hybrid policy: Migrated resource plans do not support integration between the hybrid policy and the ownership policy. When both the hybrid policy and ownership policy are enabled, migration is rejected.
Migrated resource plans maintain ownership of resources by proportion, unless you configure the resource plan to own resources by rank.

Behavior when migrating to an existing multidimensional resource plan

When you are merging a resource plan to an existing multidimensional resource plan, resource groups that are associated with the resource plan can be migrated only to existing multidimensional resource plans with the same policy and allocation strategy (stacked, balanced, exclusive). The joined resource group's consumer tree must also be a subset of the existing resource group's consumer tree. Behavior for each policy is as follows when you are migrating to an existing multidimensional resource plan:

Ownership policy: Resource groups in a migrated resource plan support the configuration of resources that they own and reserve. Multidimensional scheduling distributes resources with the sum of a consumer from each resource group.

Share policy: You can configure only the overall share ratio between consumers from the resource group configuration page. All resource groups in the migrated resource plan use the same share ratio. If the resource plan is being merged with an existing multidimensional resource plan, a warning message appears to confirm the share ratio value.

Hybrid policy: The hybrid policy is not supported for merging slot-based resource plans to multidimensional scheduling.

Viewing resource allocation for migrated resource plans

The Resource Allocation (Slot > Multidimensional) page in the cluster management console provides the resource allocation details resource plans that are migrated from slot-based scheduling to multidimensional scheduling.

To access the migrated resource plan page, click Resources > Resource Planning (Slot) > Resource Allocation (Slot > Multidimensional).

Feature interactions

Migrating a slot-based resource plan to a multidimensional scheduling resource plan supports the following interactions with other IBM® Spectrum Symphony features:

You can migrate to a multidimensional scheduling resource plan with stacked, balanced, and exclusive (consumer level and allocation level) allocations.
You can migrate to a multidimensional scheduling resource plan using borrow-only consumers with a share ratio of 0, which have less priority than non-borrow consumers with a share ratio greater than 0.
Selective reclaim is supported for migrating to multidimensional scheduling, and maps directly to multidimensional scheduling selective reclaim.