Manage Capacity Pools

This page covers common management operations for a Capacity Pool with the Momento CLI or console.

Preview availability

Momento Cache (Cluster and Flex) is available in limited preview. Request access before creating a Pool.

Available capacity and usage

The available capacity for a pool is the sum of Valkey's maxmemory as configured across all primary nodes. Replicas enable failover and improve read throughput, but do not increase a pool's available capacity.

A Cluster pool measures usage for billing purposes by counting the number of deployed instances of each type.

A Flex pool measures usage for billing purposes as the sum of Valkey's maxmemory across all deployed nodes, including both primaries and replicas.

Review the default service limits before you create or scale a Pool.

Create a Pool

With the CLI, use momento preview pool create. Cluster requires an instance type, shard count, fixed replica count, and AZ IDs; Flex requires capacity bounds, replication bounds, and AZ IDs. See Create a Capacity Pool for exact commands.

In the limited-preview console:

1. Open Capacity Pools and select Create pool.
2. Choose the region, enter the Pool name, and choose Cluster (explicit) or Flex (managed).
3. For Cluster, enter instance type, shard count, and replicas per shard. For Flex, enter the capacity and replica ranges.
4. Add one or more availability-zone IDs and create the Pool.

The current form exposes these fields directly; it does not provide Production or Dev/Test presets. The Pool appears with creating status while capacity is provisioned.

List and inspect Pools

Use momento preview pool list --profile <profile> to list Pools, provisioning, and active diagnostics in the profile's region. Use describe --name <pool> to inspect one Pool's full details or get-status --name <pool> to simply poll its lifecycle status.

The console aggregates configured regions. Use its region filter or search by Pool, region, or Database name, then select a Pool to open its Overview, Databases, and Metrics tabs. If one region cannot be reached, the console preserves results from the others and identifies the missing region.

Scale a Pool

Scale a pool by editing the Pool's configuration. Run the CLI command momento preview pool update, or open the pool's resource detail page in the console.

For a Cluster Pool, you can change instance type, shard count, replicas per shard, or zones. For a Flex Pool, you can change capacity bounds, replication bounds, or zones. A Pool cannot switch between Cluster and Flex after creation.

After applying changes to a pool, it will continue to emit an active status while it converges the cluster to the new shape. Progress or blocking issues such as insufficient capacity are surfaced as diagnostics.

Changing some configurations like instance type triggers a rolling update. The service works one shard at a time, adding a healthy replacement before removing an old node. This approach minimizes disruption during the change.

For a Flex Pool, current_capacity_gib is the last settled available capacity. target_capacity_gib is the available capacity to which the Pool is converging. These values differ only while the cluster is actively scaling.

A capacity-reducing request is checked against recent memory telemetry before the update is stored. If the current quantity of data would not fit, the request is rejected. Adjust the target capacity or reduce the amount of stored data, then re-submit the configuration change. The HTTP reference documents the underlying 409 Precondition Failed response.

Read diagnostics

A Pool reports diagnostics rather than entering a failed state. If the service cannot converge to an accepted configuration, list and the console Overview return a diagnostic such as "insufficient capacity". The service perpetually attempts to converge towards the target state, so it automatically recovers when an external impediment such as a zone or service outage resolves.

To clear a capacity diagnostic, update the Pool's provisioning toward a shape that can be satisfied, such as a different instance type or set of zones. The next reconcile tick picks up that change and clears the diagnostic after successful convergence.

An accepted Cluster update can also report scale_blocked_by_utilization if it becomes unsafe between request-time preflight and propagation. That stored update is retried automatically. This differs from a request rejected synchronously, which is not stored and must be adjusted or retried by the caller.

Read metrics

The CLI does not expose Pool metrics. In the limited-preview console, select a Pool and open its Metrics tab. It shows point-in-time memory, CPU, network receive/transmit, and eviction values from the latest scrape; it does not show historical charts.

For the seven-metric Prometheus scrape and the six-metric conditional CloudWatch contract, see Capacity Pool metrics.

Delete a Pool

Delete removes the Pool and its underlying resources. You must delete every Database in a Pool first; the action is rejected while any Database remains.

1. Delete the Databases on the Pool.
2. Run momento preview pool delete --name <pool> --profile <profile>, or open the console Pool Overview, select Delete, and confirm the irreversible action.

The Pool enters deleting and is removed when teardown completes. For the lower-level request and response contract, see the Capacity Pool API.