Elastic Compute Service:OS migration and upgrade

Use cases

When the operating system on your ECS instance reaches its end of life (EOL), you may face increased security and operational risks. We recommend replacing the EOL operating system as soon as possible. The OS migration feature lets you retain application data after the replacement, but it only supports a limited number of OS migration options.

If you do not need to retain the data on your system disk or if you require more OS options, replace the system disk to change the operating system. You can also refer to the Operating system maintenance cycle and EOL guidance for recommended migration plans and detailed procedures for your current operating system.

Pre-migration assessment

Before starting the migration, understand the limitations of the destination operating system and conduct comprehensive testing to validate all your business applications in the target environment. This ensures compatibility and performance and prevents potential issues like service disruptions or feature failures after the migration.

The OS migration tool does not support hot migration. During the migration, the source instance's system kernel and software packages are installed or updated, and the instance restarts multiple times, causing service interruptions. Therefore, before you begin, manually create a snapshot to back up your data and isolate the migration environment to avoid affecting your production workload.

Procedure

1. (Conditional) To migrate CentOS 7/8 to Red Hat 7/8, complete the following steps. Otherwise, skip this step.

   1. If the Security Center client is installed on the source system, uninstall it first.

      Note

      You can reinstall the client after the migration is complete. For more information, see Install the client.

      1. Go to the Alibaba Cloud Security Center client uninstallation page and select the target instance. For more information, see Uninstall the client.

      2. Use a remote connection tool to connect to the server and run the following command.

         wget "http://update2.aegis.aliyun.com/download/uninstall.sh" && chmod +x uninstall.sh && ./uninstall.sh
         if ! lsmod | grep AliSecGuard; then echo 'Uninstall Success'; else echo "Uninstall Failed"; fi

         A return message of Uninstall Success indicates that the Security Center client has been successfully uninstalled.

   2. Run the following command to upgrade the source system to the latest kernel version.

      CentOS 7

      # Back up the original yum repo and update to the Alibaba Cloud CentOS 7 repo.
      mv /etc/yum.repos.d/ /etc/yum.repos.d.backup/
      mkdir -p /etc/yum.repos.d/
      wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
      wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
      yum clean all
      yum makecache
      # Update and restart the system.
      yum -y update
      reboot

      CentOS 8

      # Back up the original yum repo and update to the Alibaba Cloud CentOS 8 repo.
      mv /etc/yum.repos.d/ /etc/yum.repos.d.backup/
      mkdir -p /etc/yum.repos.d/
      wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.cloud.aliyuncs.com/repo/Centos-8.repo
      wget -O /etc/yum.repos.d/epel-archive-8.repo http://mirrors.cloud.aliyuncs.com/repo/epel-archive-8.repo
      yum clean all
      yum makecache
      # Update and restart the system.
      yum -y update
      reboot

2. Start the OS migration process.

   1. Go to ECS console - Instances.

   2. In the top navigation bar, select the region where the target ECS instance is located.

   3. Click the ID of the target instance to go to its details page. Click All Operations to expand the operations panel, then search for and click Replace System Disk.

3. Select OS Migration. The system automatically performs a pre-migration check, which takes about 10 seconds. The check passes when the status changes from to .

4. Carefully read the OS migration notes, select I have read and understood the risks, and I agree to authorize Alibaba Cloud to create snapshots for all cloud disks of this instance, and then click Next.

   Note

   For a batch migration, you must also select the ECS instances to be migrated.

5. In the Replace System Disk dialog box, select a destination operating system as needed.

   1. Select the Same Destination Operating System: For a batch migration, you can migrate different instances to the same destination operating system.

   2. Select Destination Operating System by Instance: Allows you to select a different destination OS for each instance in a batch migration.

6. Click Check For Migratability to view the results. The check takes about 30 seconds. After the status shows , click Confirm Migration.

Migration verification

1. In the Replace System Disk dialog box, click the instance ID. On the Instance Details tab, check the Instance Status section to verify if the OS migration was successful.

   Note

   The migration takes about 15 to 30 minutes, not including the time to create cloud disk snapshots. During the process, you can hover over Replacing Operating System to view the migration progress.

2. When the instance status changes from Running (Replacing Operating System) to Running, the OS migration is successful.

   Important

   If the instance status is Running (Operating System Replacement Failed), the OS migration has failed. You can hover over the status to view the cause of the failure. Click Troubleshooting & Contact Us to resolve the issue. After the issue is resolved, click Retry Replacement to attempt the migration again.

3. After the migration, the instance starts automatically. The instance ID, image ID, VPC, public and private IP addresses, hostname, and machine code remain unchanged. The operating system changes to the destination OS. The original system disk data is preserved, but applications may not work correctly due to environment or dependency changes. Perform thorough testing and verification. To revert to the source system, use the automatically created snapshot to roll back the cloud disk.

Next steps

• Snapshots are automatically created for the ECS instance during migration. After a successful migration, delete any unneeded snapshots promptly to avoid additional costs. If you need to keep the snapshots, see Snapshot billing for detailed pricing rules.

• View and manage the history of OS migration tasks in the SMC console. To learn more, see Server Migration Center (SMC).

• For help with migration issues, see Troubleshoot OS migration issues (Windows), Troubleshoot OS migration issues (Linux), and the official Red Hat migration troubleshooting documentation.