ApsaraDB for MongoDB offers two instance categories — General-purpose and Dedicated — each optimized for different performance and cost profiles.
Instance categories
| Instance family | Resource allocation | Typical use case |
|---|---|---|
| General-purpose | Dedicated memory and storage; shared CPU and I/O | Price-sensitive workloads that require baseline performance stability |
| Dedicated | Dedicated memory, storage, and CPU (cloud-disk tier also dedicates I/O); dedicated-host tier occupies all resources of a physical host | Mission-critical systems in finance, e-commerce, large and medium-sized internet services, and government sectors |
General-purpose instances
General-purpose instances provide dedicated memory and storage, but share CPU and I/O resources with other instances on the same physical server. CPU resources are highly reused across instances, which maximizes cost-effectiveness.
Because CPU and I/O are shared, instances may compete for resources. Choose this category for workloads where cost efficiency matters more than guaranteed performance isolation.
Dedicated instances
Dedicated instances give your database exclusive access to CPU resources, reducing contention and delivering more consistent performance. Three sub-types are available:
| Sub-type | Resource isolation | Notes |
|---|---|---|
| Dedicated local-disk | Dedicated memory, storage, and CPU; shared I/O | I/O contention with co-located instances is still possible |
| Dedicated cloud-disk | Dedicated memory, storage, CPU, and I/O | No resource competition; higher performance stability and less affected by co-located instances than dedicated local-disk |
| Dedicated-host | All resources of a physical host | Maximum isolation; no resource competition |
The following figure illustrates the differences between General-purpose, dedicated local-disk, and dedicated cloud-disk instances.
The following graph shows the differences among General-purpose, Dedicated (local disk), and Dedicated (cloud disk) instance families.
Choose an instance category
Use the following guidance to match an instance category to your workload:
| Situation | Recommended category |
|---|---|
| Cost is the primary concern and occasional performance fluctuation is acceptable | General-purpose |
| Consistent CPU performance is required but some I/O variability is tolerable | Dedicated local-disk |
| Guaranteed CPU and I/O performance is required for a production database | Dedicated cloud-disk |
| Full host-level isolation is required for a highly critical system | Dedicated-host |
For core business systems — including financial services, e-commerce platforms, large and medium-sized internet services, and government sectors — Dedicated instances (local-disk, cloud-disk, or Dedicated-host) are the appropriate choice.
What's next
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Instance specifications: See Instance types for vCPU, memory, storage capacity, maximum connections, and IOPS details.
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Pricing: See Billable items for pricing by instance type.
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Change specifications: See Change the configurations of an instance to upgrade or downgrade your instance.