Storage vMotion works the same way as compute vMotion. The only difference is that the virtual disks and VM configuration files are moved between different datastores, not the memory between ESXi hypervisors.
Under the hood, again, a type of snapshot technology is used. When you invoke the storage vMotion, a new snapshot file is created on the datastore, and all write operations are performed on the snapshot. A base disk is switched to the read-only state so that the Storage vMotion (SvM) process can access it and the copy between datastores starts. Once the main VMDK file is transferred, the snapshot on the first snapshot is created, and the first snapshot is copied and merged to the base disk on the destination datastore. This process will be performed several times until only a small amount of data will be on the source datastore. At this time, again, the same as with compute vMotion, the VM is frozen, and the remaining bytes are copied and synced, and the VM is resumed from the new datastore.
The process of how to invoke storage vMotion is the same as with compute vMotion:
- Select a VM and open the Migrate wizard.
- Select the Change storage only option.
- Select the destination datastore to which you would like to move the VM. You can also change the disk format from thin to thick or attach a different storage policy:
