Technical support for operating systems of Elastic Compute Service (ECS) instances may be discontinued due to reasons such as end of life (EOL), end of third-party support, and evolution of open source projects. If you require technical support for the operating system of an ECS instance in the future and want to retain the data on the system disk, you can migrate or upgrade the operating system. This topic describes how to migrate and upgrade an operating system in the ECS console.
Background information
CentOS 6 reached EOL on November 30, 2020. CentOS 8 reached EOL on December 31, 2021. CentOS 7 reached EOL on June 30, 2024. We recommend that you migrate your workloads from CentOS to a different operating system to receive software updates and security patches for the new operating system.
Alibaba Cloud Linux 2 reached EOL on March 31, 2024. Alibaba Cloud provides extended support for Alibaba Cloud Linux 2 until March 31, 2025. When the extended support period ends, Alibaba Cloud will no longer provide technical support for Alibaba Cloud Linux 2. We recommend that you migrate your workloads from Alibaba Cloud Linux 2 to Alibaba Cloud Linux 3 to receive software updates and security patches for the new operating system.
Microsoft ended support for Windows Server 2008 and Windows Server 2008 R2 on January 14, 2020 and support for Windows Server 2012 and Windows Server 2012 R2 on October 10, 2023. Alibaba Cloud no longer provides software updates and security patches for these Windows Server operating systems. We recommend that you migrate your workloads from Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2 to a different operating system to receive software updates and security patches for the new operating system.
For more information, see Image maintenance cycle and EOL guidance.
Migration and upgrade scenarios
The following tables describe the operating systems that you can migrate or upgrade on ECS instances and the corresponding destination operating systems to which you can migrate or upgrade the operating systems.
Windows
Migrate Windows Server 2008 R2
Operating system architecture | Source operating system | Destination operating system |
X86 | Windows Server 2008 R2 64-bit (Chinese/English) | Windows Server 2012 R2 Datacenter 64-bit (Chinese/English) |
Windows Server 2008 R2 Enterprise 64-bit (Chinese/English) |
Migrate Windows Server 2012 R2
Operating system architecture | Source operating system | Destination operating system |
X86 | Windows Server 2012 R2 64-bit (Chinese/English) |
|
Windows Server 2012 R2 Datacenter 64-bit (Chinese/English) |
Migrate Windows Server 2016
Operating system architecture | Source operating system | Destination operating system |
X86 | Windows Server 2016 64-bit (Chinese/English) | Windows Server 2012 R2 Datacenter 64-bit (Chinese/English) |
Windows Server 2016 Datacenter 64-bit (Chinese/English) | Windows Server 2019 Datacenter 64-bit (Chinese/English) |
Linux
Migrate CentOS 7 or CentOS 8 to a different operating system
Operating system architecture | Source operating system | Destination operating system |
X86 | CentOS 7.x |
|
CentOS 8.x |
| |
ARM64 | CentOS 7.x |
|
CentOS 8.x |
|
Upgrade Alibaba Cloud Linux 2
Operating system architecture | Source operating system | Destination operating system |
x86 | Alibaba Cloud Linux 2 | Alibaba Cloud Linux 3 |
Limits
Migration limits vary based on the operating system.
Windows
Cross-language migration of Windows operating systems is not supported.
The ECS instance whose Windows operating system is to be migrated must have at least 2 vCPUs and 2 GiB of memory.
The migration tool consumes resources to download and install software packages during the migration process. Therefore, make sure that the available space of the C drive on the instance is at least 20 GiB, and the available space is larger than the size of the
C:\Windowsdirectory.
Linux
Item | Description |
General limit |
|
Limit on migrating from CentOS 7 to Alibaba Cloud Linux 2 | Alibaba Cloud Linux 2 uses kernel version 4.19, which is incompatible with kernel version 3.10 of CentOS 7. If your business uses applications that depend on kernel APIs for different purposes, such as building out-of-tree kernel modules and using hardware resources, you must assess the applications in advance and determine whether the applications can run as expected after direct migration. |
Limit on migrating from CentOS 7 to Alibaba Cloud Linux 3 | Alibaba Cloud Linux 3 uses Linux Kernel 5.10 LTS, which is incompatible with kernel version 3.10 of CentOS 7. In addition, the GNU toolchain of Alibaba Cloud Linux 3 contains GCC 10.2, Binutils 2.35, and glibc 2.32. If your business uses applications that depend on kernel APIs for different purposes, such as building out-of-tree kernel modules and using hardware resources, you must assess the applications in advance and determine whether the applications can run as expected after direct migration. |
Limit on migrating from CentOS 8 to Alibaba Cloud Linux 3 | Alibaba Cloud Linux 3 uses Linux Kernel 5.10 LTS. The GNU toolchain of Alibaba Cloud Linux 3 contains GCC 10.2, Binutils 2.35, and glibc 2.32. Alibaba Cloud Linux 3 is compatible with the CentOS 8 ecosystem. When you use the migration tool to migrate from CentOS 8 to Alibaba Cloud Linux 3, the migration tool performs a basic assessment on the source operating system. |
The following table describes the limits on migrating features or software related to your operating system.
Feature or software | Supported | Migration affected | Description |
i386-based software package | Not supported. | Yes. | Alibaba Cloud Linux does not provide i386-based software packages. If your CentOS 7 or 8 operating system is equipped with i386-based software packages, you cannot use the migration tool to migrate the operating system. To prevent system exceptions, delete the i386-based software packages before you migrate the operating system. |
epel-modular | Not supported. | No. | The Extra Packages for Enterprise Linux (EPEL) repositories of CentOS 7 or 8 and Alibaba Cloud Linux 3 depend on different platforms. You can migrate from CentOS 7 or 8 to Alibaba Cloud Linux 3. However, you cannot install software packages that are based on epel-modular after you migrate the operating system. |
Compatibility with C/C++ programs | Not guaranteed. | No. | Alibaba Cloud Linux 3 is equipped with software packages that provide better compatibility with C/C++ programs. The GNU toolchain of Alibaba Cloud Linux 3 contains GCC 10.2, Binutils 2.35, and glibc 2.32. After you migrate an operating system, we recommend that you compile and check your C/C++ programs by using the new GNU toolchain to prevent incompatibility issues. |
Kernel module compatibility | Not supported. | No. | Alibaba Cloud Linux 3 uses Linux Kernel 5.10 LTS, which is compatible with the CentOS 8 ecosystem but is not fully compatible with kernel version 3.10 of CentOS 7 and kernel version 4.18 of CentOS 8. If your business uses applications that depend on kernel APIs for different purposes, such as building out-of-tree kernel modules and using hardware resources, you must assess the applications in advance to determine whether the applications can run as expected after direct migration. |
MySQL database | Only migrations to the same or later MySQL versions are supported. |
| Alibaba Cloud Linux 3 supports MySQL. However, MySQL version downgrades are not supported. If the MySQL version provided by Alibaba Cloud Linux 3 is earlier than the MySQL version provided by CentOS 7 or 8, you cannot use the migration tool to migrate operating systems. |
Operating system hot migration | Not supported. | No. | During the migration process, software packages are re-installed. This causes services to restart and results in service interruptions. Before you perform migration, you must create snapshots for your disks to back up disk data and isolate the source operating system environment to prevent service interruptions. |
Pre-migration notes
Windows
Item | Description |
Comprehensive testing and verification | Before you migrate the operating system, we recommend that you test and verify that all your business applications are compatible with the destination operating system and run as expected in the destination operating system to ensure business continuity and functionality. Meanwhile, before and during the migration and upgrade process, the system conducts migration condition detection and pre-evaluation on the source instance. If the source system does not meet the migration conditions or the pre-evaluation fails, the migration may encounter errors and interruptions. Therefore, successful migration and upgrade cannot be guaranteed. We recommend that you familiarize yourself with migration condition limitations and troubleshooting documentation in advance and conduct tests. For more information, see Errors occurred during the migration of a Windows operating system. |
Back up your data | During the migration process, the system performs operations such as creating snapshots, reinstalling software packages, creating custom images of system disks, replacing system disks, stopping, and starting for ECS instances. We recommend that you back up important data and reasonably arrange the migration time to avoid any impact on business operations due to the aforementioned operations. |
Do not officially use the ECS cloud server until migration is complete | Migration drills or the cancellation of the migration process may result in an automatic rollback to the snapshot taken before the migration, leading to the loss of data generated during the migration period. Do not officially use the ECS cloud server until the migration task is complete. |
Evaluate the impact on business | During the migration, the operating system kernel and software packages are installed or updated and the operating system is automatically restarted multiple times. In this process, business continuity cannot be ensured. We recommend that you assess the impact of migration on your business and suspend your business before you perform a migration job. We also recommend that you do not use the source operating system during the migration. |
Ensure no snapshots are being created | If snapshots are currently being created, it will cause the migration to fail. Wait for the snapshot creation to complete before starting the migration. |
Do not perform the intermediate cloud disk | During the migration, the system automatically shares the snapshot of the Windows installation media with the current Alibaba Cloud account, and uses the snapshot to create and attach an intermediate disk to the instance. Do not perform operations on the intermediate disk during the migration. After the migration is complete, the intermediate disk is automatically detached and released. |
Linux
Item | Description |
Comprehensive testing and verification | Before you migrate the operating system, we recommend that you test and verify that all your business applications are compatible with the destination operating system and run as expected in the destination operating system to ensure business continuity and functionality. Meanwhile, before and during the migration and upgrade process, the system conducts migration condition detection and pre-evaluation on the source instance. If the source system does not meet the migration conditions or the pre-evaluation fails, the migration may encounter errors and interruptions. Therefore, successful migration and upgrade cannot be guaranteed. We recommend that you familiarize yourself with migration condition limitations and troubleshooting documentation in advance and conduct tests. |
Back up your data | During the migration process, the system performs operations such as creating snapshots, reinstalling software packages, creating custom images of system disks, replacing system disks, stopping, and starting for ECS instances. We recommend that you back up important data and reasonably arrange the migration time to avoid any impact on business operations due to the aforementioned operations. |
Do not officially use the ECS cloud server until migration is complete | Migration drills or the cancellation of the migration process may result in an automatic rollback to the snapshot taken before the migration, leading to the loss of data generated during the migration period. Do not officially use the ECS cloud server until the migration task is complete. |
Ensure no snapshots are being created | If snapshots are currently being created, it will cause the migration to fail. Wait for the snapshot creation to complete before starting the migration. |
Evaluate the impact on business | During the migration, the operating system kernel and software packages are installed or updated and the operating system is automatically restarted multiple times. In this process, business continuity cannot be ensured. We recommend that you assess the impact of migration on your business and suspend your business before you perform a migration job. We also recommend that you do not use the source operating system during the migration. |
Prerequisites
Resource Access Management (RAM) is activated. Server Migration Center (SMC) is granted the permissions to access cloud resources.
To grant the access permissions to SMC, log on to the RAM console and click Confirm Authorization Policy.
NoteIf you use a RAM user, log on to the RAM console with the corresponding Alibaba Cloud account and grant the
AliyunSMCFullAccesspolicy permissions to the RAM user.The ECS Snapshot service is activated. Snapshots are created for an ECS instance when the operating system of the instance is being migrated. For more information, see Activate ECS Snapshot.
The ECS instance whose operating system you want to migrate is in the Running state. Cloud Assistant Agent is installed and ran on the instance within the previous 24 hours.
For information about how to install Cloud Assistant Agent, see Install Cloud Assistant Agent.
The ECS instance is deployed in a virtual private cloud (VPC). If the ECS instance is in the classic network, you must migrate the ECS instance from the classic network to a VPC. For more information, see Migrate ECS instances from the classic network to a VPC.
YUM or DNF is used for migration. Make sure that these two components run as expected.
After the migration, the original system disk is released. If the Delete Automatic Snapshots While Releasing Disk feature is enabled, the associated automatic snapshots are also released by default. The Delete Automatic Snapshots While Releasing Disk feature is manually disabled if you want to retain the snapshots that are associated with the original system disk. For more information, see Delete automatic snapshots while releasing a disk.
Procedure
Open the Replace Operating System dialog box.
Log on to the ECS console.
In the left-side navigation pane, choose .
In the top navigation bar, select the region where the ECS instance resides.
Find the ECS instance that you want to manage. In the Actions column, choose
> Disk and Image > Replace Operating System. NoteTo migrate the operating systems of multiple ECS instances at a time, select the ECS instances whose operating systems you want to migrate and choose in the lower part of the Instance page.
Perform a pre-migration check.
In the Replace Operating System dialog box, select Migrate Operating System.
A pre-migration check is automatically performed and requires approximately 10 seconds to complete.
If an ECS instance passes the pre-migration check, the value in the Precheck column corresponding to the instance changes from
to 
. If an ECS instance fails the pre-migration check, the value in the Precheck column corresponding to the instance changes from
to 
. Follow the on-screen instructions to resolve the issue and then migrate the operating system of the instance.
Read the notes, select I acknowledge and accept these risks and authorize Alibaba Cloud to create snapshots for all disks on the instance, and then click Next.
NoteTo migrate the operating systems of multiple ECS instances at a time, select the ECS instances whose operating systems you want to migrate.
In the Migration Settings step, select a destination operating system for all or each of the selected instances based on your business requirements.
Select the Same Destination Operating System: If you migrate the operating systems of multiple ECS instances at a time, you can select this option and specify a destination operating system for all the selected instances.
Select Destination Operating System by Instance: If you migrate the operating systems of multiple ECS instances at a time, you can select this option and specify a destination operating system for each selected instance.
Click Check for Migratability and view the check results.
The migratability check requires approximately 30 seconds to complete.
: You can migrate the instance to the destination operating system. 
: You cannot migrate the instance to the destination operating system. You can follow the on-screen instructions to view the reason why you cannot migrate the instance to the destination operating system.
Click Migrate.
Check whether the operating systems of the ECS instances are migrated.
In the Replace Operating System dialog box, click the ID of an ECS instance.
On the Instance Details tab, check whether the operating system of the ECS instance is migrated based on the value of the Instance Status parameter.
Approximately 10 minutes are required to migrate the operating system. This excludes the time that is required to create snapshots.
If the operating system is migrated, the value of the Instance Status parameter changes from Running (Replacing Operating System) to Running.
NoteWhen the operating system is being migrated, you can move the pointer over Replacing Operating System to view the progress of the migration task.
When you migrate the operating system of an ECS instance, snapshots are automatically created for the instance. After you migrate the operating system of the instance, we recommend that you delete the snapshots that you no longer require at the earliest opportunity to prevent additional costs. For information about how to delete a snapshot, see Delete a snapshot. For information about the billing of snapshots, see Snapshots.
If the operating system fails to be migrated, the value of the Instance Status parameter changes from Running (Replacing Operating System) to Running (Operating System Replacement Failed).
NoteYou can move the pointer over Operating System Replacement Failed to view the cause of the failure and click Identify Issue & Contact Us to resolve the issue. After the issue is resolved, click Retry Replacement to migrate the operating system of the ECS instance.
References
The operating system migration or upgrade feature is provided by SMC. For more information, see What is SMC? You can view and manage migration or upgrade records of operating systems in the SMC console. You can also perform operating system migrations and upgrades in the SMC console. For more information, see Migrate an operating system.