A deployment set is a policy that controls the distribution of Elastic Compute Service (ECS) instances and implements disaster recovery and service availability when ECS instances are created.

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 the specified region based on the deployment policy that you configured.

Deployment sets support the high availability policy:

  • When you use the high availability policy, all the ECS instances within your deployment set are distributed across different physical servers within the 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.
  • When you use the high availability policy, you may not be able to create ECS instances if a supply shortage occurs in the specified region. If the economical mode is enabled for a stopped pay-as-you-go instance, the instance may fail to restart. 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, 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 Billing 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 in 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 in the following instance families can be created in deployment sets:
    • c6, g6, r6, c5, g5, ic5, and r5
    • hfc6, hfg6, hfr6, hfc5, and hfg5
    • d2, d2s, d2c, d1, and d1ne
    • i2, i2g, and i1
    • se1ne, sn1ne, and sn2ne

    For more information about instance types and their performance, see Instance families.

  • 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 No Fees for Stopped Instances (VPC-Connected).

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

References

API operations