Backup Strategies for Integrity Virtual Machines

Volume Splitting Inside the Virtual System
Another popular approach to data protection is the notion of volume splitting which draws on data
redundancy capabilities to take snapshots of data storage volumes at a given point in time. After the
split occurs, the volume management software typically tracks the changes made to the volumes so
that, subsequently, the volumes are merged back together. By periodically splitting and merging
volumes – that correspond to storage on separate storage entities – you effectively create backups of
the data residing on those volumes. There are many different implementations of such technology,
many of which have a logical implementation, so that they are independent of the specific storage
devices involved. HP’s Logical Volume Manager is one example of such technology, which provides
the capability to split a volume (lvsplit command) and then merge (lvmerge command). Figure 6
provides an example configuration for such an approach.
You typically cannot use volume-splitting technologies that rely on specific storage devices or the
behavior of a device driver when the storage is virtualized.
Figure 6 Volume splitting inside a virtual system. Note that the “split” volume or device may be backed up to a physical tape
(or other media) before the merge and resynchronization.