PolarDB:Temporarily upgrade compute node specifications

Service impact

Specification changes restart compute nodes, causing brief service disruptions. The severity depends on your cluster configuration.

Connection interruption by configuration

Additional impacts

• Change duration: Approximately 5 minutes per compute node. Changing two nodes takes about 10 minutes. Actual duration varies with cluster workload and the number of databases and tables.

• Read-only node latency: Data synchronization latency on read-only nodes may be longer than normal during the change.

• Restart order: Read-only nodes restart first, then the primary node. No primary/standby switchover occurs.

Specification changes adjust only compute resources. Existing data in the cluster is not affected.

Node specification limits

These limits ensure that read-only nodes have enough capacity to take over primary node traffic during a failover. They apply to all clusters except Multi-master Cluster (Limitless) Edition.

• At least one read-only node must have the same specifications as the primary node.

• Read-only nodes with hot standby enabled must have the same specifications as the primary node.

• The memory of a read-only node cannot be less than half the memory of the primary node.

• CPU core minimums for read-only nodes:

Limitations

• During a temporary upgrade, you can perform only one additional temporary upgrade.

• The following operations are not available during a temporary upgrade: manually downgrading specifications, adding or removing nodes, temporarily adding nodes, automatic scaling, and unsubscribing from the cluster. To perform any of these operations, first convert the temporary upgrade to a permanent one. See Convert a temporary upgrade to a permanent upgrade.

Prerequisites

Before you begin, ensure that you have:

• A Subscription cluster in the Running state

• No other configuration change tasks in progress (such as adding or removing nodes, or performing minor version upgrades)

• No pending configuration change tasks

• The AliyunServiceRoleForPolarDB service-linked role created under your Alibaba Cloud account

  Check whether the service-linked role exists

  1. Log on to the RAM console using your Alibaba Cloud account and go to Identity Management > Roles.

  2. Search for a role named AliyunServiceRoleForPolarDB.

     • If the role exists, no action is needed.

     • If the role does not exist, continue with the following steps.

     

  3. Click Create Role. On the Create Role page, click Create Service-Linked Role in the upper-right corner.

     

  4. Set Trusted Service to AliyunServiceRoleForPolarDB and click Create Service-Linked Role.

     

Perform a temporary upgrade

1. Log on to the PolarDB console. In the left navigation pane, click Clusters and select the region where the cluster is located.

2. Open the Change Configurations (Subscription) dialog box using one of the following methods:

   • Click Change Configurations in the Actions column of the target cluster.

   • Click the cluster ID to go to the Basic Information page. In the Database Nodes section, click Change Configurations.

3. Select Temporary Upgrade and click OK.

4. On the Temporary Upgrade page, review the Current Configuration and Expiration Time, then set the following parameters:

   Important

   The Restore Point cannot be changed after it is set, and it cannot be later than one day before the cluster's expiration date. For example, if the cluster expires on January 10, the latest valid restore time is January 9. If you need to extend the upgrade duration, perform a second temporary upgrade before the original restore time is reached—the new Restore Point must be later than the first.

   Parameter	Description
   Sub-series	Select the target specification edition: General Specification or Dedicated Specification.
   Node	Select the target specifications for each node to upgrade (primary or read-only). At least one read-only node must match the primary node specifications.
   Restore Point	Set the time when the system will automatically revert the specifications to their original state. The minimum duration is 1 hour and the maximum is 14 days. For periods longer than 14 days, use a manual specification change instead.

5. Read the terms of service, click Buy Now, and complete the payment. The upgrade task starts after payment.

Billing

The fee is based on the price difference between the new and original specifications, with a premium coefficient of 1.5:

Fee for N days = (Monthly price of new specifications − Monthly price of original specifications) ÷ 30 × 1.5 × N

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