What is a benefit of block-level storage virtualization?

A.
Enables users to perform nondisruptive data migrations

B.
Enables users to automatically perform zoning changes

C.
Reduces application downtime during backups

D.
Enables hosts to perform online path management

Explanation:
Block Level Storage Virtualization

Block-level storage virtualization aggregates block storage devices (LUNs) and enables
provisioning of virtual storage volumes, independent of the underlying physical storage. A
virtualization layer, which exists at the SAN, abstracts the identity of physical storage devices and
creates a storage pool from heterogeneous storage devices. Virtual volumes are created from the
storage pool and assigned to the hosts. Instead of being directed to the LUNs on the individual
storage arrays, the hosts are directed to the virtual volumes provided by the virtualization layer.
For hosts and storage arrays, the virtualization layer appears as the target and initiator devices,
respectively. The virtualization layer maps the virtual volumes to the LUNs on the individual arrays.
The hosts remain unaware of the mapping operation and access the virtual volumes as if they
were accessing the physical storage attached to them.
Typically, the virtualization layer is managed via a dedicated virtualization appliance to which the
hosts and the storage arrays are connected.
Figure in the slide illustrates a virtualized environment. It shows two physical servers, each of
which has one virtual volume assigned. These virtual volumes are used by the servers. These
virtual volumes are mapped to the LUNs in the storage arrays. When an I/O is sent to a virtual
volume, it is redirected through the virtualization layer at the storage network to the mapped LUNs.
Depending on the capabilities of the virtualization appliance, the architecture may allow for more
complex mapping between array LUNs and virtual volumes.
Block-level storage virtualization enables extending the storage volumes online to meet application
growth requirements. It consolidates heterogeneous storage arrays and enables transparent
volume access.
Block-level storage virtualization also provides the advantage of nondisruptive data migration. In a
traditional SAN environment, LUN migration from one array to another is an offline event because
the hosts needed to be updated to reflect the new array configuration.
In other instances, host CPU cycles were required to migrate data from one array to the other,
especially in a multivendor environment. With a block-level virtualization solution in place, the
virtualization layer handles the back-end migration of data, which enables LUNs to remain online
and accessible while data is migrating. No physical changes are required because the host still
points to the same virtual targets on the virtualization layer. However, the mappings information on
the virtualization layer should be changed. These changes can be executed dynamically and are
transparent to the end user.
EMC E10-001 Student Resource Guide. Module 5: Fibre Channel Storage Area Network (FC
SAN)