Changing the OS of a BMS

Scenarios

If you select a wrong OS when creating a BMS or the current OS cannot keep up with service growth, you can change the OS on the management console. The OSs of BMSs quickly provisioned and those provisioned on local disks can both be changed. During the OS change for a quickly provisioned BMS, a new system disk is allocated to the BMS. After the OS is changed, the system disk ID is updated and the original system disk is deleted.

You can change the system disk image to a public, private, or shared image. OS changes can be made between Linux OSs, Windows OSs, and also between Linux and Windows OSs.

After an OS change:

The system disk type of the quickly provisioned BMS does not change.
The IP address and MAC address of the BMS do not change.

Precautions

Changing the OS is a mission-critical operation. Before changing the OS, read the following precautions carefully:

After the BMS OS is changed, the original OS will not be retained. You are advised to back up the original OS in advance.
To change the BMS OS, you must stop the BMS, which will result in a service interruption.
After the OS is changed, the image is changed, and the system disk capacity may increase or decrease. If it decreases, fees will not be refunded to you.
During the OS change, do not stop or restart the BMS. Otherwise, the OS change may fail.

Precautions for Changing the OS Between Windows and Linux

When changing the OS between Windows and Linux, the file system format of the data disk may not be identified. In this case, you need to initialize the data disk to restore the default file system matching the OS. If you have stored important data on the data disk, you need to install specified software to identify the data.

To change Windows to Linux, install an NTFS partition tool, such as NTFS-3G for data reading and writing on the Windows BMS.
To change Linux to Windows, install software, such as Ext2Read and Ext2Fsd to identify ext3 or ext4.

You are not advised to change Linux to Windows. If there are LVM partitions on the Linux BMS, these partitions may not be identified after the OS is changed to Windows.

Constraints

Only changes between free OSs are supported.
The system disk capacity of a BMS using local disks is not displayed on the page for changing the OS.
If the EVS disk where the BMS OS is installed is deleted during the OS change, the OS change will fail.
During the OS change, you cannot change the license type or inject user data.
The OS of a BMS in maintenance state cannot be changed.

Prerequisites

The BMS whose OS is to be changed is stopped. The OSs of BMSs in OS Change failed and Reinstalling OS failed can be changed.
The target BMS provisioned quickly has a system disk.
If the boot device of the BMS is the EVS disk, the EVS disk quota must be greater than 0.
If the target BMS is created using a private image, ensure that the image still exists.
The OS change depends on the bms-network-config, Cloud-Init, and password reset plug-in in the BMS image.
- If the BMS uses a public image, ensure that the image has the bms-network-config, Cloud-Init, and password reset plug-in.
- If the BMS uses a private image, check whether bms-network-config, Cloud-Init, and the password reset plug-in are installed by following the instructions in Bare Metal Server Private Image Creation Guide.

Procedure

Log in to the BMS console.
Locate the row containing the target BMS. Click More in the Operation column and select Change OS.
The Change OS page is displayed.
Modify related BMS parameters, such as Image Type and Image, based on service requirements.

If the system disk capacity of a yearly/monthly BMS is less than the target image size, expand the system disk capacity first.

For details about how to expand the system disk capacity, see Expanding the Capacity of an EVS Disk in Elastic Volume Service User Guide.
Set Login Mode.
If the current OS is Linux, select Key pair or Password. If the current OS is Windows, select Key pair.
- Key pair: You can select an existing key pair or click Create Key Pair and create a private key used to log in to the BMS.
- Password: You can set the initial password for logging in to the BMS OS. The new password must meet the password complexity requirements listed in Table 3.
Click OK.
In the Change BMS OS dialog box, confirm the specifications, read and agree to the agreement or disclaimer, and click Submit Application.
After the application is submitted, the BMS status changes to Changing OS. The OS change is complete when the BMS status changes to Running. After the OS is changed, the BMS will start automatically.