メインコンテンツまでスキップ

Provisioning and sizing

You size a Capacity Pool when you create it. Momento Cache offers two ways to size a pool, corresponding to its two variants: Cluster (size by instance) and Flex (size by capacity in GB). You choose one when you create the pool.

Cluster: size by instance​

A Cluster pool takes four inputs:

  • Instance type for the nodes.
  • Shard count, the number of Valkey shards the keyspace is split across.
  • Replica count, the number of replicas of each shard for redundancy and read capacity.
  • Availability zones the pool may use. Choose more than one for production.

Cluster sizing exists because teams that plan capacity and cost at the instance level need it. You keep full control of the topology and its cost.

Flex: size by capacity​

A Flex pool abstracts over instances. Instead of naming instance types and counts, you choose:

  • Minimum and maximum capacity in GiB for the pool. Set the bounds equal to pin capacity.
  • Minimum and maximum replicas per shard for redundancy and read capacity. Set the bounds equal to pin replication.
  • Availability zones the pool may use. Choose more than one for production.

Momento maps these bounds to available configurations and automatically grows or shrinks the topology within the capacity range as memory utilization changes. Flex suits teams that want capacity-oriented sizing without managing instance topology.

Pool capacity is the configured Valkey maxmemory per primary shard multiplied by the number of primary shards. Replicas do not add capacity. Flex usage, which is the billable quantity, includes deployed maxmemory on both primaries and replicas. Memory utilization measures live used_memory relative to maxmemory; it is not another capacity value.

Choosing a shape​

  • Shards determine how the keyspace and throughput scale horizontally. Add shards for more memory and aggregate throughput.
  • Replica count adds redundancy and read capacity. Use at least one replica per shard for production. Flex expresses this choice as replication bounds.
  • Zones control where the pool may run. Momento automatically distributes nodes across the configured zones for you. Choose two or more zones for production so that an outage in one zone does not take the pool down.

You can change any of these after creation by updating the pool. See Manage Capacity Pools.

Choosing a variant​

Use Cluster when you plan capacity and cost at the instance level and want full control of the topology. Use Flex when you would rather size by GB and let Momento manage low-level configuration. The two are otherwise the same service with the same Valkey, the same gateway, and the same capabilities.