Write a short note on virtualization provisioning.

Virtual Storage Provisioning

➢ Virtual provisioning enables creating and presenting a LUN with more capacity than 

is physically allocated to it on the storage array.

➢ The LUN created using virtual provisioning is called a thin LUN to distinguish it 

from the traditional LUN.

➢ Thin LUNs do not require physical storage to be completely allocated to them at the 

time they are created and presented to a host.

➢ Physical storage is allocated to the host “on-demand” from a shared pool of physical 

capacity.

➢ A shared pool consists of physical disks.

➢ A shared pool in virtual provisioning is analogous to a RAID group, which is a 

collection of drives on which LUNs are created.

➢ Similar to a RAID group, a shared pool supports a single RAID protection level. 

However, unlike a RAID group, a shared pool might contain large numbers of drives.

➢ Shared pools can be homogeneous (containing a single drive type) or heterogeneous 

(containing mixed drive types, such as flash, FC, SAS, and SATA drives).

➢ Virtual provisioning enables more efficient allocation of storage to hosts.

➢ Virtual provisioning also enables oversubscription, where more capacity is presented 

to the hosts than is actually available on the storage array.

➢ Both shared pool and thin LUN can be expanded non-disruptively as the storage 

requirements of the hosts grow.

➢ Multiple shared pools can be created within a storage array, and a shared pool may be 

shared by multiple thin LUNs.