Changing an OS

Scenarios

If the OS running on the cloud server in a FlexusL instance cannot meet service requirements, you can change the OS to another OS version or type.

Notes

• An OS change does not make any changes to server specifications.
• After the OS is changed, the server IP address remains unchanged.
• Data in all partitions (including the system partition) of the system disk will be cleared, so you are advised to back up the system disk data prior to an OS change.
• An OS change does not affect data in data disks.
• After the OS is changed, the original OS is not retained.
• After you change the OS, you need to deploy services in the new OS.
• After the OS is changed, the server automatically starts.
• Do not reset the password of, restart, or stop the FlexusL instance immediately after the OS is changed. Wait for several minutes until the system successfully injects the password, or the login will fail.

Constraints

• Application images have the minimum CPU and memory specification requirements. If the specification of a FlexusL instance is low, you cannot change its OS using an application image. For example, you cannot change the OS of a FlexusL instance with 2 vCPUs and 4 GiB memory to the GitLab application image that needs to use at least 2 vCPUs and 8 GiB memory. To do so, upgrade the FlexusL instance first and try again.
• After the OS is changed, the login password is cleared. You need to reset the password for logging in to the new OS. If you switch to an application image, reset the password only after the image with the pre-installed application is up and running, or the password reset may fail.
• Restrictions on private images of FlexusL instances are as follows.

  Table 1 Restrictions on private images of FlexusL instances

  Item	Description
  Region	The FlexusL instance and the private image must belong to the same region. Otherwise, the image cannot be used to create the FlexusL instance. Therefore, before creating a FlexusL instance from a private image, create a private image in the region where the target FlexusL instance resides.
  Server architecture	Only x86 is supported.
  Image type	Only system disk images are supported. Data disk images and full-servers images are not supported. Linux system disk images only support the following image sources: free public Linux images provided by Huawei Cloud, images created from FlexusL instances that are created using application images, and third-party private images you have imported. Other billed Linux images created from KooGallery images are not supported. Windows system disk images with the Bring Your Own License (BYOL) license are supported. NOTE: FlexusL instances do not support full-server images. If you want to migrate an entire server to a FlexusL instance, use Server Migration Service (SMS). For details, see Migrating Servers Using Server Migration Service (SMS).
  Password reset plug-in	If a private image is created from a server on another cloud platform or downloaded from a third party, the private image may fail to be used to create a FlexusL instance or change the OS of an existing FlexusL instance because the onekey_resetpasswd tag is missing. For details, refer to What Should I Do If a Private Image Cannot Be Used to Create a FlexusL Instance or Change the OS of an Instance Because the Password Reset Plug-in Is Not Installed on the Image or the onekey_resetpasswd Tag Is Missing?

Preparations

Before using a private image to change the OSs of multiple FlexusL instances, use Image Management Service (IMS) to create an image first.

Before creating images, make sure you have learned about the restrictions on private images of FlexusL instances.

Billing

An OS change does not involve refund or supplementary payment.

Procedure

1. Log in to the FlexusL console and click a resource card to go to the instance details page.
2. Change the OS using any of the following methods.
   • Method 1: Locate the target FlexusL instance, choose > Change OS.
   • Method 2: On the Overview page, choose > Change OS in the upper right corner.

     

   • Method 3: On the Cloud Servers page, choose > Change OS in the row containing the target server.

     

   • Method 4: On the Cloud Servers page, click the target server name. In the upper right corner of the displayed page, choose > Change OS.
3. Specify the parameters required for changing the OS.
   • Select the image to be switched.

     FlexusL provides OS images, a rich variety of application images, and private images for you to select. Before using a private image, you need to learn about the restrictions on private images of FlexusL instances first and then create a private image. For details, see Images Supported by FlexusL Instances.

   • Select Stop server. The server must be stopped before its OS can be changed.

   

4. Read and agree to the agreements, and click Submit.

   After the OS is changed, the server automatically starts. When the server status is Running, the OS change is complete.

   

   • Do not reset the password of, restart, or stop the FlexusL instance immediately after the OS is changed. Wait for several minutes until the system successfully injects the password, or the login will fail.
   • After the OS is changed, the login password is cleared. You need to reset the password for logging in to the new OS. If you switch to an application image, reset the password only after the image with the pre-installed application is up and running, or the password reset may fail.

FAQs

• If you use a Linux private image to change the OS of a FlexusL instance and the private image is created from a server on another cloud platform or downloaded from a third party, the image may not have the password reset plug-in installed. As a result, the password reset function is unavailable. To install the plug-in, refer to the following:
  • What Should I Do If the Password Cannot Be Reset After I Use a Private Linux Image to Create a FlexusL Instance or Change the OS of an Existing Instance and I Forgot the Initial Password of the Private Image?
  • What Should I Do If the Password Cannot Be Reset After I Use a Private Linux Image to Create a FlexusL Instance or Change the OS of an Existing Instance and I Know the Initial Password of the Private Image?
• If you use a private image to change the OS of an HECS L instance, and the Host Security Service (HSS) is not protecting the instance, enable HSS by referring to What Do I Do If HSS Is Not Started After I Use a Private Image to Create an L Instance or Change the OS of an Instance?