Sistina's LVM: Linux Volume Manager. LVM allows the growth and shrinkage of partitions, as one would expect, but also allows the creation of snapshot partitions, enabling consistent online backups or recovery in filesystems and database systems.
IBM's EVMS Enterprise volume management system. The EVMS Project has the goal of providing unparalleled flexibility and extensibility in managing storage. It represents a new approach to logical volume management, as the architecture introduces a plug-in model that allows for easy expansion or customization of various levels of volume management. See information about the combined setup of Heartbeat v2 on the Xensource Wiki page on a SAN based EVMS-HA Xen solution