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Capacity Pool

A Capacity Pool is the dedicated Valkey capacity you provision. You declare its size and Momento provisions and operates the backing cluster, handling the instance lifecycle, reconciliation, and health. A Capacity Pool is the isolation boundary of Momento Cache.

Sizing a pool​

When you create a Capacity Pool, you specify the physical shape of the capacity:

  • Instance type for the nodes.
  • Shard count, the number of Valkey shards.
  • Replicas per shard, for redundancy and read capacity.
  • Availability zones for placement.

See Provisioning and sizing for how to choose these values and for the sizing modes the service supports.

Managing capacity​

You can change a pool's size after creation by updating its configuration. Momento converges the running cluster to the new shape. Scaling behavior and safeguards are covered in Manage Capacity Pools.

Lifecycle​

A Capacity Pool moves through three states: creating, active, and deleting. You can create Databases on a pool once it is active. Deleting a pool is rejected while any Database is still assigned to it; remove the Databases first.

If Momento cannot provision the requested capacity (for example, when a cloud region lacks capacity for the requested instance type), the pool reports a diagnostic that you can read and monitor. The cluster does not have a failed state, since the control plane will continue attempting to converge to the target configuration.

To resolve a capacity diagnostic, update the pool's configuration (for example, choose a different instance type or zones). The control plane will adjust provisioning to match the new configuration. See the API reference for available diagnostic fields.

Databases exist within a Capacity Pool​

A Capacity Pool provides the compute and storage for Databases. Databases in the same pool share its resources. A Database belongs to exactly one pool.