When a production site becomes unrecoverable due to a major incident (such as fire, power outage, or system failure), the ECS disaster recovery (DR) facilitates a cross-zone failover of the entire application. This protects against single-zone failures and helps achieve core Recovery Time Objective (RTO) and Recovery Point Objective (RPO) metrics.
Before you begin
Before implementation, you must designate a separate DR zone that resides within the same region and VPC as your production environment. Within this designated DR zone, ensure you have vSwitches configured for both the replication network and the recovery network. These networks can share the same vSwitch.
Step 1: Create a DR site pair
To create a site pair for cross-zone disaster recovery of the production ECS instances, follow these steps:
Log on to the Cloud Backup console.
In the left-side navigation pane, choose .
Click Switch to CDR.
Click Add.
In the Create Site Pair panel, set Type to Cross-zone Disaster Recovery and select the VPC that is created for the production site.
Click Create.
Step 2: Add the servers to be protected
To add the servers (ECS instances) to be protected, perform the following steps:
Click the Protected Server tab. In the upper-right corner of the tab, select the DR site pair that you created in Step 1 from the drop-down list.
On the Protected Server tab, click + Add. Select the ECS instances and click OK.
Up to 10 ECS instances can be selected.
In the Server Status column, the status of the added ECS instances is Agent Installing and then changes to Initialized. If the status of an ECS instance is not Initialized, choose in the Operation column to initialize the instance.
Step 3: Start replication
To enable real-time replication of ECS instances to Alibaba Cloud, perform the following steps:
On the Protected Server tab, find the ECS instance that you want to replicate and choose in the Operation column.
In the Enable Replication panel, configure the parameters and click Start.
Parameter
Description
Recovery Point Policy
Select the interval at which recovery points are created from the drop-down list. Unit: hours. For example, if you select 1 hour, Cloud Backup creates a recovery point every hour.
Hard Disk Type
Select Ultra Disk, ESSD, or SSD.
Replication Network
Select the vSwitch used to replicate data from the production zone to the DR zone.
The drop-down list is automatically populated with available vSwitches from the DR site's VPC.
Recovery Network
Select the vSwitch in the DR zone used to create and run ECS instances during a failover or drill.
The drop-down list is automatically populated with available vSwitches from the DR site's VPC.
Automatic restart after replication interruption
Specify whether to automatically resume replication if an interruption occurs. If you select this check box, the replication task is restarted after the replication is interrupted.
The ECS instance then enters the Enabling Replication, Replicating Full Data, and Replicating states in sequence.
Enabling Replication: ECS disaster recovery is scanning data on the ECS instance and evaluating the overall data volume. In most cases, this process takes a few minutes.
Replicating Full Data: ECS disaster recovery is replicating valid data from the ECS instance to Alibaba Cloud. The replication duration depends on factors such as the data volume and the network bandwidth of the ECS instance. The progress bar in the Server Status column shows the replication progress.
Replicating: After all valid data on the ECS instance is replicated to Alibaba Cloud, Aliyun Replication Service (AReS) monitors all disk write operations on the ECS instance and replicates the incremental data to Alibaba Cloud in real time.
(Optional) Perform a disaster recovery drill
After an ECS instance enters the Replicating state, you can perform a disaster recovery drill on the ECS instance.
A disaster recovery drill is an important part of disaster recovery. It allows you to run a protected ECS instance on the cloud to verify that your applications can run as expected. A disaster recovery drill has the following benefits:
Allows you to easily check whether an application can run on a restored ECS instance as expected.
Familiarizes yourself with the disaster recovery process and ensures that a smooth failover can be performed if the production site encounters a failure.
To perform a disaster recovery drill, perform the following steps:
On the Protected Server tab, find the ECS instance on which you want to perform a disaster recovery drill and click Test Failover in the Operation column.
In the Test Failover panel, configure the following parameters: Recovery Network, IP Address, Use ECS Specification, Hard Disk Type, Recovery Point, Elastic Public Network IP, and Post Script. Then, click Start.
NoteCloud Backup automatically retains 24 recovery points that are created in the most recent 24 hours for each ECS instance.
If you do not select Use ECS Specification, you must set the CPU and Memory parameters.
Alibaba Cloud then runs the application on a restored ECS instance at the specified time. The disaster recovery drill does not affect real-time data replication.
After the disaster recovery drill is completed within a few minutes, click the link in the Test Failover Information column to verify restored data and applications.
Clear the drill environment.
After the verification is completed, click Cleanup Test Environment in the Operation column. Then, the restored ECS instance is deleted.
NoteAfter the restored ECS instance is verified, we recommend that you delete the restored ECS instance at the earliest opportunity to reduce costs.
Step 4: Perform a failover
Regular disaster recovery drills ensure that you can run your applications on restored ECS instances at any time. If a critical error occurs at the production site, you can switch your workloads to the disaster recovery site.
Failover is applicable to protected ECS instances where a critical error occurs. During the failover, ECS disaster recovery stops real-time data replication. To resume replication for a protected ECS instance, you must choose More > Server Operation > Restart Replication in the Operation column.
To initiate a failover, perform the following steps:
On the Protected Server tab, find the ECS instance and choose in the Operation column.
In the Failover panel, configure the following parameters: Recovery Network, IP Address, Use ECS Specification, Hard Disk Type, Recovery Point, Elastic Public Network IP, and Post Script. Then, click Start.
ImportantYou can restore the ECS instance to the current point in time only once.
After the failover is completed, click the link in the Recovered Instance ID/Name column to verify the restored data and applications.
If the applications run as expected after being restored to the current point in time, choose in the Operation column.
NoteAfter you complete the failover or change the recovery point and verify that the applications restored from the protected ECS instance are running your business, you can commit the failover to release the cloud resources that are occupied during failover to save resources.
If the applications do not meet the requirements after being restored to the current point in time, for example, data in the restored database is inconsistent with that in the source database or dirty data on the source ECS instance is synchronized to the restored ECS instance in the destination region, choose in the Operation column to change the recovery point before you commit the failover.
NoteThe procedure for changing the recovery point is similar to that for failover, except that you must select a recovery point earlier than the current point in time.
Step 5: Perform a failback
Failback is the process of returning operations from the DR site back to the original production site after a disaster is resolved. This process involves a reverse replication to synchronize any data changes that occurred at the DR site before the final cutover.
To perform a failback, perform the following steps:
On the Protected Server tab, find the ECS instance and choose in the Operation column. In the message that appears, confirm that you want to perform a reverse registration on the ECS instance.
In the Operation column, choose .
In the Initiate Reverse Replication panel, configure the following parameters: Original machine recovery, Replication Network, and Recovery Network. Then, click Start.
WarningCross-region disaster recovery and cross-zone disaster recovery allow you to replicate applications back to the original ECS instance. However, when you replicate applications back to the original ECS instance, data on the original ECS instance is overwritten. Perform this operation with caution.
After the ECS instance enters the Reverse Replicating Data in Real Time state, choose in the Operation column.
In the Failback panel, configure the following parameters: CPU, Memory, Recovery Network, IP, and Execute script after recovery. Then, click Start.
After the failback is completed, choose in the Operation column to register the protected ECS instance again.