Server Migration Center:Operating system migration (Linux)

Background information

When the operating system of your ECS instance enters the end of life (EOL) phase, as described in Overview of operating system lifecycles, you may face increased security and operational risks. We recommend that you replace the operating system as soon as possible. The operating system migration feature of Server Migration Center (SMC) provides several migration solutions. After the migration, the operating system kernel and major system packages are upgraded, while the data on the system disk is retained.

Migration solutions

Migration limitations

Usage notes for migration

Billing

During the migration, the system creates snapshots of all disks on the ECS instance to back up data. You are charged for these snapshots on a pay-as-you-go basis. For more information, see Product Billing.

Procedure

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

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

      Note

      You can reinstall it after the migration is complete. For more information, see Manual installation.

      After the agent is uninstalled, Security Center still protects your server for 24 hours. If you want to reinstall the agent, install the agent 24 hours later. If you want to reinstall the agent within 24 hours after the agent is uninstalled, you must run the installation command at least three times and ignore the error messages during the installation. Otherwise, the reinstalled agent is automatically uninstalled.

      1. Go to the Alibaba Cloud Security Center client uninstallation interface and select the instance from which to uninstall the client. 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

         The Uninstall Success message indicates that the Security Center client is uninstalled.

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

      CentOS 7

      # Back up the original yum software source and update it to the Alibaba Cloud CentOS 7 source.
      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 software source and update it to the Alibaba Cloud CentOS 8 source.
      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. Migrate the operating system.

   Fast migration (Recommended)

   Note

   To use the SMC console to import the information about a migration source, make sure that the following conditions are met:

   • Cloud Assistant Agent is installed on the migration source. By default, Cloud Assistant Agent is installed on ECS instances that are created based on public images after December 1, 2017.

   • If you want to import the information as a Resource Access Management (RAM) user, the AliyunECSAssistantFullAccess policy is attached to the RAM user to grant the RAM user the permission to manage Cloud Assistant. For more information, see Grant permissions to a RAM user.

   1. Go to SMC console - Operating System Migration.

   2. On the Operating System Migration page, click Start Migration.

   3. In the Operating System Migration dialog box, select the ECS instance to migrate by its instance ID and region, and then click Pre-check.

      

   4. In the Operating System Migration dialog box, the system automatically performs a pre-migration check, which takes about 10 seconds.

      • If the pre-check status changes from to , the pre-check is successful.

      • If the pre-check status changes from to , the pre-check failed. Follow the prompts on the interface to resolve the issue and then try migrating again.

   5. After you carefully read the notes for operating system migration, select I Have Read And Understood The Preceding Risks, And I Agree To Authorize Alibaba Cloud To Create Snapshots For All Disks Of This Instance, and then click Next.

      

   6. In the Operating System Migration dialog box, you can select the destination operating system.

      • Migrate To The Same Destination Operating System: If you perform a batch migration, you can migrate multiple instances to the same operating system.

      • Select Destination Operating System By Instance: If you perform a batch migration, you can migrate multiple instances to different operating systems.

   7. Click Check If Migratable to view the migration check result.

      The check takes about 30 seconds.

      • : The operating system can be migrated.

      • : Migration is not supported. You can view the reason for the failure in the interface prompts.

   8. Click Confirm Migration.

      You can view the progress of the operating system migration on the Operating System Migration page.

      Warning

      During the operating system migration, do not manually stop, restart, or release the ECS instance. Do not use O&M scripts to perform these operations. Otherwise, the migration fails.

   Staged migration

   Step 1: Import the migration source

   Migration sources can be servers of a variety of types to migrate, such as servers in data centers, VMs, and hosts on third-party cloud platforms. SMC supports multiple methods to import the information about migration sources. You can select a method based on your business requirements. For more information, see the How do I choose a method to import migration sources? section of the "FAQ" topic.

   Command-line one-click import of migration source (Recommended)

   Important

   • The source server must be accessible over the Internet. If your source server is protected by a firewall, refer to What are the service domains of SMC? and ensure that the corresponding domains and ports are whitelisted in your network security policy.

   • If your source server cannot access the Internet or you want to improve migration efficiency through the VPC, use the method of importing by client.

   1. Go to SMC console - Operating System Migration.

   2. On the OS Migration page, click Import Migration source.

   3. Configure the parameters as prompted and copy the activation code command. The following table describes the parameters.

      Parameter	Description
      Migration Source Type	Select Alibaba Cloud ECS Instance.
      Import Method	Select Use CLI to Import Server. Generate an activation code and a command, and run the command on the migration source.
      Activation Quota	The number of migration sources whose information you want to import by using the activation code. Valid values: 1 to 1000. Default value: 200.
      Validity Period	The validity period of the activation code. Unit: day. Valid values: 1 to 90. Default value: 90.
      Activation Code	The activation code. Perform the following steps to generate the activation code and copy the generated command: Click Generate. Click the Linux Shell tab. Click Copy to copy the activation code command.

   4. Log on to the source server and paste and run the copied command as an administrator to import the information about the migration source.

      1. Log on to the Linux server.

      2. Paste and run the copied command as an administrator to import the information about the migration source.

         

         After the command is run, if a message similar to Import Source Server [s-bp18x8751kgz2oyh****] Successfully! is returned, the information about the migration source is imported.

   5. On the Operating System Migration page of the SMC console, view the status of the migration source in the Real-time Migration Status column.

      • If the status of the migration source is Migration Source Online, the migration source is successfully imported.

      • If the migration source is in another state, the import failed. Troubleshoot the failure based on the following solutions and then import the migration source again:

        • Troubleshoot the failure based on the error message in the console or the log file in the SMC client installation directory. By default, the SMC client is installed in /smc.

        • For information about common issues and their solutions, see SMC FAQ and Troubleshoot errors.

   Import a migration source using the SMC client

   For more information about the SMC client, see SMC client usage guide.

   1. Go to SMC console - Operating System Migration.

   2. On the OS Migration page, click Import Migration source.

   3. On the Import Migration Source page, configure the parameters. The following table describes the parameters.

      Parameter	Description
      Migration Source Type	Alibaba Cloud ECS Instance
      Import Method	Select Client Import.
      Import Description	After the Import Description, download the corresponding SMC client based on the source server's operating system (Linux or Windows) and bit version (32-bit or 64-bit).

   4. Import the information about the migration source.

      Important

      During the migration, do not shut down the SMC client until the migration is complete. Otherwise, the migration source is disconnected from the SMC console, and the migration fails.

      1. You can use a remote connection tool that supports file transfer. For example, you can use WinSCP to upload the SMC client package to the source Linux server.

      2. Connect to the source Linux server and decompress the SMC client package.

         Linux 64-bit Generic is used in the example. Run the following command to decompress the package. If you use another version of the SMC client, replace the package name in the command with the name of your SMC client.

         tar -zxvf go2aliyun_client.tar.gz

         Note

         Linux ARM64 supports the g6r general-purpose instance family and the c6r compute-optimized instance family. For more information about instance types, see the "Arm-based enterprise-level computing instance families" section of the Overview of instance families topic.

      3. (Optional) Exclude the files or directories that you do not need from the migration. For more information, see the How do I filter or exclude files or directories from migration? section of the "FAQ" topic.

         Important

         If you enable the block replication feature, you cannot exclude files or directories from the migration job.

      4. Obtain an activation code or AccessKey pair.

         • (Recommend) Obtain an activation code: In the Description section in the SMC console, click Generate and copy the generated activation code information.

         • Obtain an AccessKey pair: An AccessKey pair consists of an AccessKey ID and an AccessKey secret. If no AccessKey pair is created, create one first. For more information, see Obtain an AccessKey pair.

      5. In the SMC client folder, run the following commands to run the SMC client.

         cd go2aliyun_client_linux_x86_64
         sudo chmod +x go2aliyun_client
         sudo ./go2aliyun_client

      6. Enter the activation code or AccessKey pair as prompted. The following figure shows an example of an activation code.

         The following messages may appear after you enter the activation code.

         • If no snapshot dependency is installed on your source server, a message appears. The following figure shows the details of the message. You can decide whether to install a snapshot dependency based on whether you enable the block replication feature.

           • If you want to enable block replication for the migration, enter yes to automatically install a snapshot dependency.

           • If you do not want to enable block replication for the migration, enter no.

           Important

           If the snapshot dependency fails to be installed, do not enable block replication when you create a migration job. Otherwise, the migration may fail.

           

         • The rsync tool is installed on most mainstream migration sources. If rsync is not installed on the migration source, the SMC client displays a message. Enter yes to install rsync, as shown in the following figure.

         • If SELinux is enabled on the migration source, a message that prompts you to disable SELinux appears. Enter yes to disable SELinux. The following figure shows how to disable SELinux.

         If the information about the migration source is imported, a message similar to the following one is returned: Import Source Server [s-bp11npxndknsycqj****] Successfully!.

         Note

         If the information about the migration source fails to be imported, you can troubleshoot the issue based on the returned message. After you fix the issue, run the following commands to exit the background program and re-import the information about the migration source. For more information about FAQ and solutions, see FAQ and Errors occurred during a server migration.

         sudo ./go2aliyun_client --abort
         sudo ./go2aliyun_client

   5. On the Operating System Migration page of the SMC console, view the status of the migration source in the Real-time Migration Status column.

      • If the status of the migration source is Migration SourceOnline, the information about the migration source is imported.

      • If the migration source is in another state, the information fails to be imported. In this case, troubleshoot the failure based on the following solutions and import the information about the migration source again:

        • Troubleshoot the failure based on the error message in the console or the log file in the SMC client installation directory. By default, the SMC client is installed in /smc.

        • For more information about frequently asked questions (FAQ) and solutions, see FAQ and Errors occurred during a server migration.

   Step 2: Migration configuration

   1. Find the migration source that you want to manage and click Start Migration in the Actions column.

   2. In the Migration Configuration dialog box, configure the parameters.

      The following table describes the operating system migration parameters:

      • Current Operating System: The current operating system is displayed by default and cannot be modified. Example: CentOS 7.

      • Destination Operating System: From the drop-down list, select the operating system to which you want to migrate. Example: Alibaba Cloud Linux 3.

      • Migration Drill (Optional):

        Decide whether to enable Migration Drill. This feature is enabled by default and is supported only for Linux operating system migrations. For more information, see Configure a migration drill.

        Note

        A migration drill simulates and verifies a migration solution before the actual migration. It helps you understand the feasibility and risks of the migration solution, which reduces potential problems and data loss during the actual migration.

        A migration drill can help you quickly identify potential problems, provide solutions, and improve the success rate of the migration.

      • Execution Method (Conditional):

        If Migration Drill is enabled, you can select a migration drill execution method from the Execution Method drop-down list. The default option is Drill And Migrate.

        The following list describes the differences between the two methods:

        • Drill Only: Creates only a migration drill task. After the migration drill is complete, if an operating system migration is required, you must manually start the migration task.

        • Drill And Migrate: After the migration drill is complete, if no drill items are in the Critical state, the system automatically starts the operating system migration task.

   3. Click Start Migration. In the Please Confirm Operating System Migration dialog box, carefully read the notes and then click I Confirm I Have Been Informed.

   4. On the Operating System Migration page, view the real-time migration status.

      Warning

      During the operating system migration, do not manually stop, restart, or release the Linux instance. Do not use O&M scripts to perform these operations. Otherwise, the migration fails.

Verify the migration result

• If the real-time migration status is Completed, the operating system migration is successful.

  

  Note

  After the migration task is complete, the ECS instance automatically restarts. During the system initialization phase, operations such as updating software packages are performed. Do not perform any operations on the ECS instance until the system successfully starts. The system initialization phase takes about 15 to 30 minutes. The specific duration depends on the number of system software packages.

  In the Actions column for the destination migration source, click View Destination Instance. Then, on the instance details page, check whether the operating system is migrated to the destination operating system.

  Important

  After the migration, the source instance is migrated to the new system kernel and software packages. The original system disk data remains unchanged. However, applications may not run as expected due to changes in the environment or dependencies, which can cause business failures. You must perform thorough testing and verification.

• If the Real-time Migration Status is Error, the migration task has encountered an error.

  In this case, you need to perform the following operations:

  1. Click Troubleshoot Errors in the Actions column and fix issues based on the error code and description. For more information, see FAQ and Errors occurred during a server migration.

  2. After the issues are fixed, click Retry Migration in the Actions column of the migration job.

     The migration job resumes from the point where it was suspended.

     Important

     If the intermediate instance is released, you must create another migration job. For more information, see the What do I do if I accidentally release an intermediate instance? section of the "FAQ" topic.

  To roll back the data on the source system disk, you can use the automatically created backup snapshot to restore the data. The steps are as follows:

  1. Go to the ECS console - Snapshots.

  2. In the Actions column of the automatically created backup snapshot, click Roll Back Disk.

  3. In the Roll Back Disk dialog box, click Confirm.

Clear resources

During the migration, SMC creates one pay-as-you-go snapshot named SMC_Backup_Snapshot_XXX for disks of the ECS instance for data backup. If you no longer need this snapshot, delete it in time to avoid unnecessary charges. For more information, see Delete a snapshot.