Milvus allows you to upgrade a single-AZ instance to an intra-city multi-AZ disaster recovery instance online to enhance high availability and disaster recovery capabilities. This topic describes the background, limits, and procedure for the upgrade.
Background
In a single-AZ instance, all components are deployed within a single availability zone. If that availability zone fails, the service becomes unavailable. To improve business continuity, you can upgrade your single-AZ instance to an intra-city disaster recovery instance. This distributes components across multiple availability zones within the same region, providing AZ-level disaster recovery.
Milvus currently supports the following two intra-city disaster recovery modes:
Mode | Description | Resource changes |
Multi-AZ Basic Edition | In this mode, node resources run in a single availability zone. If the primary availability zone fails, service is restored in a standby AZ. This mode does not double your node resources, making it a cost-effective option. | The number of node resources does not change. After the primary availability zone fails, nodes with the same number of replicas are immediately launched in the standby AZ. |
Multi-AZ High-availability Edition | Node resources are deployed with an equal number of replicas in two availability zones, providing real-time hot standby at the AZ level. In case of a primary AZ failure, failover to the standby AZ completes in seconds. This mode is suitable for production environments and scenarios with high availability requirements. | The number of replicas for all service nodes is doubled, which generates an upgrade order. |
Currently, you can only upgrade from a single-AZ deployment to either the Multi-AZ Basic Edition or the Multi-AZ High-availability Edition. Direct upgrades from the Multi-AZ Basic Edition to the Multi-AZ High-availability Edition are not yet supported.
Prerequisites
The instance is in the Running state.
The instance is a Single-zone Deployment deployment.
The target standby AZ is in the same region as the instance.
A VSwitch has been created in the target standby AZ within the same VPC as the instance.
Limits
Instances that do not support automatic upgrades
Some older instances cannot be upgraded automatically from the console due to limitations in their underlying architecture. To upgrade these instances, you must submit a ticket for manual assistance.
Region | Condition |
China (Zhangjiakou) | Instances created before December 17, 2023 |
China (Hong Kong), China (Beijing) | Instances created before December 19, 2023 |
Germany (Frankfurt), Singapore, China (Ulanqab) | Instances created before December 23, 2023 |
China (Hangzhou), China (Shenzhen), China (Shanghai) | Instances created before December 25, 2023 |
If your instance matches one of the conditions above, please submit a ticket for assistance.
Other limits
During the upgrade, some query or write operations might time out or fail. We recommend performing the upgrade on your production cluster during off-peak hours.
If public access is enabled for the instance, the upgrade process temporarily disables it, causing a brief interruption. Public access is automatically re-enabled upon completion.
When upgrading to the Multi-AZ High-availability Edition, an upgrade order is generated. Ensure that your account has a sufficient balance.
Procedure
Log on to the Milvus management console.
In the top navigation bar, select the region where the instance is located.
On the Instances page, find your instance and click its instance ID to open the instance details page.
In the Instance Configuration section of the instance details page, click Upgrade to the right of Deployment Mode.
In the upgrade configuration panel, set the following parameters:
Parameter
Description
Deployment Model
Select the disaster recovery mode. Options include Multi-zone Deployment (Basic) or Multi-zone Deployment (HA).
Standby AZ VSwitch
Select a VSwitch in the standby AZ. The VSwitch must be in the same VPC as the instance.
Review the configuration details and cost changes, then click OK.
If you selected the Multi-AZ High-availability Edition for a subscription instance, complete the payment on the order page.
After the upgrade is complete, the instance's deployment mode updates to the selected multi-AZ mode. You can view the updated deployment mode on the instance details page.