Instance Groups
Instance Group is a feature that lets you group multiple Instances together and control how they are distributed across physical infrastructure through an Affinity policy. When you create a group, you choose one of two policies to tell the system how to place Instances: prefer the same host server or prefer different host servers.
Two Affinity Policies
Soft Affinity
The system prefers to place Instances on the same physical host server. If the host server lacks sufficient resources, Instances are still created on a different server instead of failing.
When to use: You want to optimize internal network performance but availability is more important — for example, application servers or worker nodes.
Soft Anti Affinity
The system prefers to place Instances on different physical host servers. If no other host has sufficient resources, Instances are still created on the same host as existing Instances instead of failing.
When to use: You want to increase availability — if one physical host goes down, not all Instances in the group are affected at the same time.
Limits
| Item | Value |
|---|---|
| Maximum number of groups per VPC | 10 |
| Maximum number of Instances per group | 10 |
| Minimum number of Instances per group | 2 |
| Number of groups an Instance can belong to | 1 |
Important: Each Instance can only belong to one Instance Group. To move an Instance to a different group, you must first remove it from the current group.
Availability
Instance Group is available on both VPC types:
| VPC Type | Available |
|---|---|
| Specific VPC | Yes |
| General VPC | Yes |