Item | Description |
Impacts on the system disk | After you replace the operating system of an ECS instance, Alibaba Cloud assigns a new system disk to the instance. Take note of the following items: The original system disk is released, and all data and partition information of the disk are cleared. The system disk ID changes. However, the category of the system disk, the IP addresses of the instance, and the media access control (MAC) addresses of the elastic network interfaces (ENIs) on the instance remain unchanged.
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Impacts on the data disks | If the replacement involves the same operating system type, such as Windows or Linux, the replacement operation replaces the system disk but does not affect the data disks attached to the instance. Take note that the disks must be re-attached to the instance. If the replacement involves different operating system types, such as Windows and Linux, the replacement operation replaces the system disk and causes an issue that the new operating system cannot recognize the file system format on the data disks. You must re-initialize the data disks or install software to recognize the file system format on the data disks. For more information, see the What to do next section of this topic.
Important If the custom image that you use to replace the operating system of an ECS instance contains data from data disks, make sure that no business dependency exists between the original system disk and the data disks attached to the instance or no issues occur when the new system disk performs operations on the data disks. For example, if the original system disk read data from and wrote data to the data disks, exceptions may occur when the new system disk reads data from and writes data to the data disks. |
Impacts on snapshots | Snapshots of the original system disk cannot be used to roll back the new system disk but can be used to create custom images. Manual snapshots of the original system disk are not released. If you enable Delete Automatic Snapshots While Releasing Disk for the original system disk, the automatic snapshots of the disk are automatically released together with the disk. If you disable Delete Automatic Snapshots While Releasing Disk for the original system disk, the automatic snapshots of the disk are retained until they expire. The automatic snapshot policy applied to the original system disk becomes invalid, and you can configure an automatic snapshot policy for the new system disk based on your business requirements.
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Limits that apply when you replace an operating system with a Windows operating system | Make sure that the system disk has at least 1 GiB of free space. Otherwise, the ECS instance may fail to start after the operating system is replaced. Starting January 14, 2020, Microsoft no longer provide support for Windows Server 2008 and Windows Server 2008 R2. Starting October 10, 2023, Microsoft no longer provides support for Windows Server 2012 R2. Alibaba Cloud no longer provides technical support for ECS instances that run the preceding operating systems. If your ECS instances run the preceding operating systems, we recommend that you upgrade to Windows Server 2016 or later at the earliest opportunity. For more information, see Windows Server EOL guidance.
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Limits that apply when you replace a Windows operating system with a Linux operating system or replace a Linux operating system with a Windows operating system | Operating systems of ECS instances can be replaced between Windows and Linux operating system families only in regions in the Chinese mainland. In regions outside the Chinese mainland, the operating systems of ECS instances can be replaced only within the same operating system family. Check whether the hostname of the ECS instance meets the requirements of the replacement operating system. For example, if the replacement operating system is a Windows operating system, the instance hostname cannot exceed 15 characters in length. For information about how to change the hostname, see Modify the attributes of an instance or ModifyInstanceAttribute.
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Charges | You are not charged for replacing the operating system of an ECS instance, but you are charged for the resources that are used in the following scenarios: If you use a paid image as the replacement image, you are charged for the image. For more information, see Images. If you extend the system disk when you replace the operating system of an ECS instance, you are charged for the additional disk capacity. For more information, see Block storage devices.
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Time required to replace the operating system | Approximately 10 minutes is required to replace the operating system of an ECS instance. The actual amount of time varies based on the operating system. Important After the operating system is replaced, you may be unable to log on to the ECS instance by using Virtual Network Computing (VNC) for specific reasons, such as slow boot. In this case, log on to the instance again later. |