| name | documentdb-storage |
| description | Storage configuration guidance for Azure DocumentDB — when and how to use Premium SSD v2 high-performance storage, IOPS/bandwidth caps that are gated by compute tier (not disk size), Premium SSD v2 limitations (no CMK, migration paths, disk-hydration sequencing), and storage capacity change limits. Use when picking a storage type at cluster creation, sizing for I/O-intensive workloads, migrating from Premium SSD to Premium SSD v2, or sequencing compute/storage/HA changes on a Premium SSD v2 cluster. |
| license | MIT |
Storage — Azure DocumentDB
Azure DocumentDB clusters use remote premium SSD storage. Two disk types are offered:
| Storage type | IOPS / bandwidth scaling | Max IOPS | CMK | Use it for |
|---|
| Premium SSD (v1) | Scales with disk capacity — bigger disk → higher IOPS | 20,000 | ✔️ | Legacy clusters, scenarios that require CMK |
| Premium SSD v2 | Decoupled from disk size — IOPS/bandwidth gated by compute tier | 80,000 | ❌ | New production clusters; any I/O-intensive workload |
Premium SSD v2 is the default recommendation for new clusters. It delivers up to a 12× performance boost at no added cost by removing the disk-size lever from the IOPS equation — you size storage for capacity and size compute for throughput, independently.
How Premium SSD v2 changes sizing
On Premium SSD v1, hitting 20,000 IOPS required provisioning a 20 TB disk even when only ~1 TB of data was stored. On Premium SSD v2, the highest achievable IOPS and bandwidth for the chosen compute tier are auto-configured regardless of disk size:
- Choose storage size based on how much data the cluster will hold.
- Choose compute tier based on how much IOPS / MBps the workload needs (see storage-tier-iops-caps).
- No knobs to tune — the upper-bound IOPS/bandwidth for the tier are applied automatically at no extra cost.
Rules
References
