Create and release a GDN - PolarDB - Alibaba Cloud Documentation Center

A global database network (GDN) consists of multiple PolarDB clusters that are deployed in multiple regions within a country. Data is replicated across all clusters in each GDN. This allows applications that are deployed across different regions to access a database that is local to their region, which provides reliable access with low latency. This topic describes how to create and release a GDN.

Prerequisites

A primary PolarDB cluster is created. For more information, see Purchase a pay-as-you-go cluster and Purchase a subscription cluster.

Limits

A cluster in a GDN must meet the following requirements:
- A PolarDB for MySQL 8.0.2 cluster
- A PolarDB for MySQL 8.0.1 cluster
- A PolarDB for MySQL 5.7 cluster whose revision version is 5.7.1.0.13 or later
- A PolarDB for MySQL 5.6 cluster whose revision version is 5.6.1.0.27 or later
The primary cluster and secondary clusters must have the same database engine version, which can be MySQL 8.0, MySQL 5.7, or MySQL 5.6.
A GDN consists of one primary cluster and up to four secondary clusters. For more information about limits on their regions, see Region mappings between the primary and secondary clusters.
Note
To add more secondary clusters, go to Quota Center. Click Apply in the Actions column corresponding to GDN cluster upper limit adjustment.
A cluster belongs to only one GDN.
Clusters in the GDN do not support specifications of 2 cores and 4 GB of memory or 2 cores and 8 GB of memory.
Clusters in the GDN do not support the database and table restoration feature.
The primary cluster in a GDN cannot be of Single Node Edition.

Pricing

You are not charged for the traffic that is generated during cross-region data transmission within a GDN. You are charged only for the use of PolarDB clusters in the GDN. For more information about the pricing rules of PolarDB clusters, see Billable items overview.

Create a GDN

Log on to the PolarDB console.
In the left-side navigation pane, click Global Database Network.
On the Global Database Network page, click Create GDN.

In the Create GDN dialog box, configure the following parameters.

Parameter	Description
Name	The name of the GDN that you want to create. We recommend that you set a descriptive name that makes it easy to identify. GDN names do not have to be unique.
Primary Region	The region where the primary cluster is deployed. Note Select the region where the primary cluster is deployed.
Primary Cluster	Select an existing cluster as the primary cluster of the GDN.

Click OK.
Note
After you create a GDN, you can add secondary clusters. For more information, see Manage a secondary cluster.

Release a GDN

Log on to the PolarDB console.
In the left-side navigation pane, click Global Database Network.
Find the GDN that you want to release and click Delete in the Actions column.
Important
- A GDN can be released if it contains only the primary cluster.
- A GDN cannot be restored after it is released. Proceed with caution.
- Applications that are connected to the endpoints of a GDN cannot access databases after the GDN is released. Modify the application code to change the connection string of the GDN at your earliest opportunity.
In the Delete GDN message, click OK.

FAQ

How many GDNs can I create for an Alibaba Cloud account?
The number of GDNs that you can create is unlimited.
After a GDN is created, can I change the primary cluster of the GDN?
No, you cannot change the primary cluster after the GDN is created. You can create another GDN, select the required cluster as the primary cluster, and then release the current GDN.
Note
Before you release the GDN, remove all secondary clusters from the GDN.