Changing a QingTian ECS to a KVM ECS (Windows)

Scenarios

Certain C6 ECSs use the QingTian virtualization architecture. When you change a C6 ECS running Windows to a KVM ECS, there may be a Blue Screen of Death (BSOD) or startup exception (error code 0xc000000f).

This section describes how to change a C6 ECS running Windows from the QingTian virtualization architecture to KVM.

• KVM ECS flavors: See the Virtualization column in A Summary List of x86 ECS Specifications.
• QingTian C6 ECS flavors: See the Virtualization column in A Summary List of x86 ECS Specifications.

When you modify the specifications of a C6 ECS, the system automatically checks the virtualization architecture of that ECS. If the ECS is using the QingTian architecture, you can perform operations described in this section if there is an exception.

Background

After the specifications are modified, a BSOD or startup exception may occur because ECSs of different architectures load different protocols and drivers.

• KVM Windows ECSs load the virtio-blk driver, and the corresponding registry is Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\viostor.
• Certain C6 Windows ECSs using the QingTian architecture load the virtio-scsi driver, and the corresponding registry is Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\vioscsi.

Check whether there is the StartOverride item in the registry path of the driver.

• If the value of the REG_DWORD field is 0, the ECSs use the driver in this path upon the next startup.
• If the value of the REG_DWORD field is not 0, the ECSs do not use the driver in this path upon the next startup.

When a QingTian Windows ECS is changed to a KVM ECS, if the driver of the corresponding protocol used by the system disk is not loaded, the system disk cannot be identified, resulting in a BSOD or startup exception.

Constraints

• The ECS needs to be stopped during the specification modification, so you are advised to perform this operation during off-peak hours.
• The network type cannot be changed during the specification modification.
• QingTian ECSs can only have SCSI disks attached. They do not support VBD disks. The disks use WWN identifiers.

Process

Figure 1 shows the flowchart for changing a QingTian C6 ECS to a KVM ECS.

Figure 1 Flowchart for changing a QingTian C6 ECS to a KVM ECS

Step 1: Back Up an ECS

If you modify the specifications of an ECS without installing the driver, the ECS may become unavailable and the data on the system disk may be lost. You are advised to back up the ECS first to prevent data loss.

1. Check the ECS.

   Before backing up the ECS, stop and then start the ECS to ensure that services can run properly after the ECS is started.

2. Back up the ECS.
   Backing up ECSs will generate storage costs. There are two types of EVS snapshots: standard snapshots and legacy snapshots. Legacy snapshots are in OBT and free of charge. Standard snapshots are billed. Select the one type as required.

   • Method 1: Create a backup for the ECS.

     For details, see ECS Backup Procedure.

   • Method 2: Create a system disk snapshot and a data disk snapshot.

     For details about how to create a snapshot, see Creating an EVS Snapshot in the Elastic Volume Service User Guide.

Backups and snapshots created for the ECS are used to restore data. If the specifications fail to be modified, you can use the backups or snapshots to restore data.

• To use backups to restore data, see Restoring from a Cloud Server Backup.
• To use snapshots to roll back data, see Rolling Back Disk Data from a Snapshot.

After the specifications are modified, if services are running properly, delete the ECS backups or snapshots from the corresponding service console.

Step 2: Check the Drivers

1. Log in to the ECS.
2. In the Run dialog box, enter regedit to access the registry editor.
3. In the registry, locate the following entries:

   Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\vioscsi

   Computer\HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\viostor

   Check whether the StartOverride item exists.

   • If StartOverride does not exist and there are only Enum and Parameters in the directory, no changes need to be made.
     Figure 2 Registry
     
   • If StartOverride exists in the vioscsi registry path, go to 4.
   • If StartOverride exists in the viostor registry path, go to step 5.
4. Check the StartOverride item in the vioscsi registry path and change the value of the field whose type is REG_DWORD from 0 to 3.

   If the value is already 3, you do not need to change it.

5. Check the StartOverride item in the viostor registry path and change the value of the field whose type is REG_DWORD from 3 to 0.

   If the value is already 0, you do not need to change it.

6. Restart the ECS.
7. Repeat steps 2 to 3 to check whether StartOverride exists in the registry.

   If there are only Enum and Parameters in the path, the change is successful.

Step 3: Modify Specifications

1. Log in to the ECS console and access the ECS list page.
2. On the Elastic Cloud Server page, view the status of the target ECS.

   If the ECS is not in Stopped state, choose More > Stop in the Operation column.

3. Choose More > Modify Specifications in the Operation column.

   The Modify ECS Specifications page is displayed.

4. Select the new ECS type, vCPUs, and memory.
5. (Optional) Set DeH.

   If the ECS is created on a DeH, you can change the DeH where the ECS resides.

   To do so, select the target DeH from the drop-down list. If no DeH is available in the drop-down list, it indicates that DeH resources are insufficient and cannot be used to create the ECS with new specifications.

6. Click Next.
7. Confirm the new specifications, read and agree to the agreement, and then click Submit Application.
   

   • The cloud platform automatically creates a system disk snapshot for you. After the specifications are modified, manually delete the snapshot on the snapshot page if you have verified that services are running properly.
   • If ECS specifications failed to be modified and the ECS becomes unavailable, reinstall the OS. This operation will clear the data on the system disk while the data on data disks is retained.

(Optional) Step 4: Check Disk Attachment

After a QingTian C6 ECS is changed to a KVM ECS, disk attachment may fail. Therefore, check disk attachment after specifications are modified. If disks are properly attached, the ECS change is successful.

• Windows ECS

  For details, see Why Do the Disks of a Windows ECS Go Offline After I Modify the ECS Specifications?

Follow-up Procedure

If the ECS specifications have been modified but the OS cannot be started after you remotely log in to the ECS, contact customer service to restore or reinstall the OS. For details, see Reinstalling the OS.

Reinstalling the OS will clear the system disk data, but the data on data disks is not affected.

After specifications are modified, check that services are running properly and then manually delete the snapshot on the snapshot page.