VMware Storage VMotion in Action
Storage VMotion enables the migration of LUN-independent virtual machine disk files while the virtual machine is running, using core VMware technologies such as disk snapshots, REDO logs, parent/child disk relations and snapshot consolidation. Here’s how it works:
- Before moving disk files, Storage VMotion creates a new virtual machine home directory for the virtual machine in the destination datastore.
- Next, a new instance of the virtual machine is created. Its configuration is kept in the new datastore.
- Storage VMotion then creates a child disk for each virtual machine disk that is being moved to capture a copy of write activity, while the parent disk is in read only mode.
- The original parent disk is copied to the new storage location.
- The child disk is re-parented to the newly copied parent disk in the new location.
- When the transfer to the new copy of the virtual machine is completed, and the original instance is shut down. Then, the original virtual machine home is deleted from VMFS at the source location.
This entire process takes about the same amount of time as a cold migration and will be a function of the size of the virtual machine disk. The final switch over from the original virtual machine to the newly instance takes place in under two seconds and is transparent to the application user. Storage VMotion uses high-level copier technologies that are not storage type specific. This means it will work with whatever type of storage you have in place.
Take the Next Step
Learn about your storage connectivity options when using Fibre Channel, iSCSI and NAS equipment or find resources and best practices for deploying shared storage for virtual machines.
