Storage Virtualization
SAN Recovery - Storage Virtualization
Storage virtualization is the process of abstracting logical storage from physical storage. There are three main types of implementation approaches: host-based virtualization, storage device-based virtualization and network-based virtualization.
Host-Based Virtualization
In host-based virtualization, physical disks presented to the host system are handled by a traditional physical device driver. There is a software layer above this device driver to intercept the I/O requests. Such a design eliminates additional requirements of hardware or infrastructure components. Examples of host-based virtualization vendors are NetApp Multistore / FlexVol, Symantec VERITAS Storage Foundation and FalconStor Software NSS Virtual Appliance for VMware
Storage Device-Based Virtualization
In storage device-based virtualization, a primary storage controller provides virtualization services and allows downstream attachment of other devices. The primary storage controller provides the pooling and meta-data management services. It may also provide replication and migration services across the controllers under virtualization process. Hitachi Data Systems Universal Storage Platform is an example of such implementation.
Network-Based Virtualization
The most common network-based virtualization application is Fibre Channel networks connected as storage area network (SAN). In such systems, the virtualization device sits in the SAN and acts as the abstraction layer between the host performing the I/O and the storage controllers providing storage capacity. This is an example of typical heterogeneous storage virtualization.
Network-based storage virtualization is also divided into two: appliance based and switch based. Appliance based devices sit between the hosts and storage. Switch based devices reside in the physical switch hardware that is used to connect the SAN devices.
In short, storage virtualization enables backup, archiving and recovery of data more easily by disguising the actual complexity of the SAN.
