What is a metaLUN in EMC Clariion ?

A metaLUN is created by combining 2 or more LUN's.MetaLUNs are supported only on CX-Series storage systems.The metaLUN feature lets you dynamically expand the capacity of a single LUN (base LUN) into a larger unit called a metaLUN. You do this by adding LUNs to the base LUN. You can also add LUNs to a metaLUN to further increase its capacity. Like a LUN, a metaLUN can belong to a Storage Group, and can participate in SnapView, MirrorView and SAN Copy sessions.During the expansion process, the host is able to process I/O to the LUN or metaLUN and access any existing data on the Base LUN. It does not, however, have access to any added capacity until the expansion is complete. Depending on the operating system, a reboot of the host or the use of a disk expansion utility, such as diskpar in Windows, may be used to claim the additional space. Each set of striped LUNs is called a component. All metaLUNs contain at least one component which includes the base LUN and one or more LUNs. Any data that gets written to a metaLUN component is striped across all the LUNs in the component. You can expand a LUN or metaLUN in two ways — stripe expansion or concatenate expansion. A stripe expansion takes the existing data on the LUN or metaLUN, and restripes (redistributes) it across the existing LUNs and the new LUNs you are adding.The stripe expansion may take a long time to complete and will affect performance while the expansion is in process . A concatenate expansion creates a new metaLUN component that includes the new LUNs and appends this component to the end of the existing LUN or metaLUN. There is no restriping of data between the original storage and the new LUNs. The concatenate operation completes immediately.

Salient Features :- 

# A metaLUN is created by combining LUNs

– Dynamically increase LUN capacity

– Can be done on-line while host I/O is in progress

– A LUN can be expanded to create a metaLUN and a metaLUN can be further expanded by adding additional LUNs

– Striped or concatenated

# Data is restriped when a striped metaLUN is created

# Appears to host as a single LUN

– Added to storage group like any other LUN

– Can be used with MirrorView, SnapView, or SAN Copy

# Supported only on CX family with Navisphere 6.5+