Navisphere Command Line Interface (CLI) Reference - VMware Communities

LUN Expansion (MetaLUN) CommandsMetaLUNs overviewA metaLUN is a type of LUN whose maximum capacity is thecombined capacities of all the LUNs that compose it. The metaLUNfeature lets you dynamically expand the capacity of a single LUN(base LUN) into a larger unit called a metaLUN. You do this byadding LUNs to the base LUN. You can also add LUNs to a metaLUNto further increase its capacity. Like a LUN, a metaLUN can belong toa storage group, and can participate in SnapView, MirrorView andSAN Copy sessions.During the expansion process, the host has access to any existing dataon the LUN or metaLUN, but it does not have access to any addedcapacity until the expansion is complete. Whether you can actuallyuse the increased user capacity of the metaLUN depends on theoperating system running on the servers connected to the storagesystem.A metaLUN may include multiple sets of LUNs that are stripedtogether and are independent of other LUNs in the metaLUN. Eachset of striped LUNs is called a component. All metaLUNs contain atleast one component which includes the base LUN and one or moreLUNs. Any data that gets written to a metaLUN component is stripedacross all the LUNs in the component.You can expand a LUN or metaLUN in two ways — stripe expansionor concatenate expansion. A stripe expansion takes the existing dataon the LUN or metaLUN, and restripes (redistributes) it across theexisting LUNs and the new LUNs you are adding. The stripeexpansion may take a long time to complete. A concatenateexpansion creates a new metaLUN component that includes the newLUNs and appends this component to the end of the existing LUN ormetaLUN. There is no restriping of data between the original storageand the new LUNs. The concatenate operation completesimmediately.326 EMC Navisphere Command Line Interface (CLI) Reference