A deployment set is a policy that controls the distribution of Elastic Compute Service (ECS) instances. You can use deployment sets to design how to implement disaster recovery and service availability when you create ECS instances.

Deployment policy

You can use a deployment set to distribute your ECS instances to different physical servers to ensure high service availability and implement underlying disaster recovery. When you create ECS instances in a deployment set, Alibaba Cloud starts the ECS instances on different physical servers within a specified region based on your configured deployment policy.

Deployment sets support the following policies:
  • Deployment set-based high availability policy

    When you use the deployment set-based high availability policy, all ECS instances within your deployment set are distributed across different physical servers within a specified region. The high availability policy applies to application architectures where ECS instances must be isolated from each other. The policy significantly reduces the chances of service unavailability.

  • Deployment set group-based high availability policy

    When you use the deployment set group-based high availability policy, each deployment set can be divided into up to seven deployment set groups. Multiple instances in a deployment set can be distributed to different deployment set groups as needed. Instances in different deployment set groups are strictly distributed to different physical servers. Instances in the same deployment set group are not guaranteed to be strictly distributed to different physical servers.

Note If a supply shortage occurs in a specified region, you may not be able to create ECS instances or restart stopped pay-as-you-go instances that are in economical mode in that region. In these cases, we recommend that you wait a while and try again.

Deployment example

The following figure shows a typical example on how to use a deployment set to improve business reliability. In the deployment set, four ECS instances are distributed to four different physical servers. Deployment set overview

If you want to achieve low-latency communication between ECS instances, we recommend that you keep the network types of the instances the same. For example, you can select the same virtual private cloud (VPC) for the ECS instances when you create them.

Billing

Deployment sets are free of charge, but you are charged for the usage of ECS instances, disks, snapshots, images, and public bandwidth in deployment sets. For more information, see Overview.

Limits

Before you use deployment sets, take note of the following items:

  • Deployment sets cannot be merged.
  • You cannot create preemptible instances in deployment sets.
  • You cannot create dedicated hosts in deployment sets.
  • When you create ECS instances in a deployment set, you can create up to 20 ECS instances within each zone. This limit varies with your ECS usage. You can use the following formula to calculate the maximum number of ECS instances that you can create in a deployment set within a region: 20 × Number of zones within the region.
  • Instances of the following instance families can be created in deployment sets:
    • c7, g7, r7, c6, g6, r6, c5, g5, r5, c6e, g6e, r6e, c7se, g7se, r7se, r6se, c7t, g7t, r7t, c7a, g7a, r7a, c6a, g6a, r6a, g5ne, re6, re4, and ic5
    • hfc7, hfg7, hfr7, hfc6, hfg6, hfr6, hfc5, and hfg5
    • d2s, d2c, d1, d1ne, d1-c14d3, and d1-c8d3
    • i3, i3g, i2, i2g, i2ne, i2gne, and i1
    • se1ne, sn1ne, sn2ne, and se1
    • ebmg5, sccgn6, scch5, sccg5, scch5s, and sccg5s
    • s6, t6, xn4, mn4, and n4
    • gn6i
    You can call the DescribeDeploymentSetSupportedInstanceTypeFamily operation to query instance families that support deployment sets.
  • Supply shortage may result in a failure to create an instance or restart a pay-as-you-go instance that is in economical mode in a deployment set. For more information, see Economical mode.

For more information about the limits and quotas of deployment sets, see the "Deployment set limits" section in Limits.

References

API operations