Configuring virtual disk resources on a live virtual machine (VMware)
You can modify CPU, memory, and virtual disk settings of a virtual machine while the virtual machine is powered on.
About this task
- Add CPU resources to the virtual machine while it is powered on.
- Add memory resource to the virtual machine while it is powered on.
- Increase virtual disk size of the virtual machine while it is powered on.
The VMware driver of IBM® Cloud Manager with OpenStack uses the Nova API to add CPU, memory, or root disk size for VMware instances while the virtual machine is running.
- enable_vm_hot_resize: If set to true, the parameter allows the capability of adding CPU, memory or resizing a disk of a virtual machine that is powered on.
- strict_resize_memory: If set to true, the parameter adds memory strictly according to the flavor. The VMware hypervisor only allows you to add memory while the memory increase size is a multiple of the hotPlugMemoryIncrementSize setting. If the memory increase size specified by the new flavor is not a multiple of the hotPlugMemoryIncrementSize setting, and strict_resize_memory is True, then the IBM Cloud Manager with OpenStack VMware driver does not add the memory. If strict_resize_memory is set to False, then the IBM Cloud Manager with OpenStack VMware driver calculates a new memory increase size. The size used is approximately equal to the increase size specified by the flavor and the driver attempts to add the memory.
The IBM Cloud Manager with OpenStack VMware driver reuses the Nova instance resize API. When the driver receives a request to resize a VMware instance, it examines the cpu/memory/disk changes specified by the flavor, Nova configuration option, and the setting of the VMware virtual machine to determine whether the operation can be performed. If it can be performed, the driver starts the operation, which does not power off the instance. If it cannot be performed, then it starts the original Nova instance resize operation, which powers off the instance. After the operation is successful, the state of the Nova instance moves from RESIZE to ACTIVE automatically. The Nova confirm resize operation is not required for this instance.
The IBM Cloud Manager with OpenStack VMware driver cannot revert a hot resized instance. The instance does not move to VERIFY_RESIZE state after the resize operation is complete. Therefore, a revert resize request is not accepted. A new resize operation can be requested to change the instance flavor back to its original flavor. If the virtual machine is powered off during the resize, the resized instance can be reverted.