ApsaraDB for MongoDB supports three storage types: enterprise SSDs (ESSDs), ESSD AutoPL disks, and local SSDs. This topic describes each storage type, compares their performance and pricing, and provides guidance on when to use each.
Storage types
ESSDs
ESSDs are built on a next-generation distributed block storage architecture and integrated with 25 Gigabit Ethernet and Remote Direct Memory Access (RDMA) technologies. They handle up to 1 million random read/write requests per second and deliver consistently low I/O latency.
ESSDs are available in three performance levels (PLs):
| Performance level | Description |
|---|---|
| PL1 ESSD | The baseline performance level. |
| PL2 ESSD | Delivers approximately 2x the IOPS and throughput of a PL1 ESSD. |
| PL3 ESSD | Delivers up to 20x the IOPS and 11x the throughput of a PL1 ESSD. Suitable for workloads that require high IOPS, high throughput, and low read/write latency under heavy concurrency. |
For a detailed comparison of capacity range, maximum IOPS, and maximum throughput across PL levels, see ESSDs.
Limitations
Storage can be scaled up but not scaled down.
Scaling completes in minutes.
Standalone instances: A transient disconnection occurs during scale-out because the instance restarts.
Replica set and sharded cluster instances: Scale-out does not cause a transient disconnection.
ESSD AutoPL disks
ESSD AutoPL disks are compatible with all features of ESSDs, provide the same baseline performance as PL1 ESSDs, and support provisioned performance on top of that baseline. Storage capacity and disk performance are decoupled, so you can scale each independently to handle workload fluctuations without overprovisioning.
For details on features, specifications, billing, and configuration, see ESSD AutoPL disks.
Limitations
Storage can be scaled up but not scaled down.
Scaling completes in minutes.
Standalone instances: A transient disconnection occurs during scale-out because the instance restarts.
Replica set and sharded cluster instances: Scale-out does not cause a transient disconnection.
Local SSDs
Local SSDs reside on the same physical host as your ApsaraDB for MongoDB instance, which minimizes I/O latency.
Limitations
Storage sizes depend on the instance type: Available storage sizes vary based on the instance type. You can scale up storage, but your choices are constrained by the instance type. Storage cannot be scaled down.
Scale-up takes hours, not minutes, because data must be copied to the new disk. Services remain available during the copy process.
Scale-up may cause a transient disconnection: If the host has enough resources, the scale-up completes in place with no disconnection. If the host has insufficient resources, the instance migrates to another machine, which causes a transient disconnection.
Compare storage types
| Dimension | ESSD | ESSD AutoPL disk | Local SSD |
|---|---|---|---|
| I/O performance | Low latency and high IOPS. | Low latency and high IOPS, with I/O burst support. | Low latency and high IOPS. |
| Configuration flexibility | Storage can be scaled up independently. Cannot be scaled down. | Storage capacity and provisioned performance can each be scaled up independently. Cannot be scaled down. | Storage can be scaled up, but available sizes depend on the instance type. Cannot be scaled down. |
| Scale-up duration | Minutes. | Minutes. | A few hours (data copy required). Services remain available. |
For a full comparison of maximum capacity, maximum IOPS, and maximum throughput across these storage types, see Block storage performance.
Pricing
The prices listed here are for reference only. The actual price is shown in the ApsaraDB for MongoDB console.
| Storage type | Price |
|---|---|
| PL1 ESSD | USD 0.33 per GB-month |
| PL2 ESSD | USD 0.66 per GB-month |
| PL3 ESSD | USD 1.32 per GB-month |
| Local SSD | USD 0.33 per GB-month |
ESSD AutoPL disk pricing combines a storage fee and an IOPS fee:
Storage fee: USD 0.33 per GB-month
IOPS fee:
USD 0.00000089 per IOPS per hour in the following scenarios:
Node storage 500–1,000 GB with provisioned IOPS 0–11,200
Node storage 1,001–2,000 GB with provisioned IOPS 0–19,200
Node storage 2,001–32,768 GB with provisioned IOPS 0–32,000
USD 0.00000893 per IOPS per hour in all other scenarios
Pricing examples:
PL2 ESSD, 500 GB, max throughput 370 MB/s:USD 330/month (500 GB x USD 0.66 per GB-month)
ESSD AutoPL disk, 500 GB, provisioned IOPS 10,000, max throughput 500 MB/s:USD 171.408/month (500 GB x USD 0.33 per GB-month + USD 0.00000089/IOPS/hour x 24 hours x 30 days x 10,000 IOPS)
View the storage type of an instance
Log on to the ApsaraDB for MongoDB console. On the Basic Information page of an instance, check Storage Type in the Specification Information section.