Each Cassandra database employs a single Capacity Unit (CU) by default, which represents three database nodes that are grouped together. A single CU represents three replicas of approximately 500 GB of user data.
CU's ensure high availability by implementing a consistent replication factor that is acceptable for both development and production workloads.
Pricing for DataStax Astra on Google Cloud Platform is based on a combination of Capacity Unit (CU) and Service Tier.
The Service Tier represents the amount of compute power allocated to each CU, and represents three compute instances per CU. DataStax Astra on Google Cloud Platform provides three Service Tiers:
- Developer: low-cost development option, 25 GB storage.
- Startup: starter configuration for development and light production workloads.
- Standard: higher throughput, lower latency, 99.9% uptime SLA, plus support.
- Enterprise: highest throughput, lowest latency, 99.99% uptime SLA, and best support tier.
To calculate cost, multiply the number of CUs by the Service Tier price. Pricing is presented in the DataStax Astra console in hourly terms, but billed in one-minute granularity.