XEN SVM

Virtualization technology allows organizations to put their business application on the host's hardware. In Storage virtualization, the company will differentiate logical storage from physical storage through abstraction. The concept is used to describe this separation at any layer in the storage software and hardware stack.

Implementation methods

There are three main types of implementation approaches that can be adopted by organizations viz. host-based, storage device-based and network-based.

Host-based: It requires specific device drivers supplemented by additional software. Specific examples of the approach are Symantec VERITAS Storage Foundation, FalconStor Software NSS Virtual Appliance for VMware, etc. They use various technologies like Logical volume management, File systems e.g. (links, CIFS/NFS) or Automatic mounting e.g. (autofs).

Storage device-based: Here, a primary storage controller or host offers the virtualization services and provides the direct attachment of other storage controllers. Various vendors are providing such services that include 3PAR Inc, Hitachi Data Systems Universal Storage Platform-V/VM, Violin Memory High-Speed Storage Platform for Virtualization-V/VM, etc.

Network-based: When the services rely on a network based device and using iSCSI or FC Fibre channel networks to connect as a SAN (Storage Area Network). Examples for such approach include EMC Invista, IBM SAN Volume Controller (SVC), HP StorageWorks Enterprise Virtual Array Family, etc.

Benefits of Storage Virtualization

1.    Non-disruptive data migration: One of the main benefits of storage virtualization is transfer of data to another location without affecting the operation of any client. Hence, the meta-data can be simply updated from the new location on host's server, which is called as data migration.

2.    Improved efficiency: Through, pooling, migration and thin provisioning services, IT administrators can allocate the free space to the data storage. You can also expand the existing disc or add new logical disk in the system.

3.    Fewer steps for management: There are multiple independent storage devices present in storage virtualization that may be scattered over a network, but it can be managed centrally without much steps.

Risks associated with the technology

1. Back up execution: After the formation of abstraction layer, only the host knows about the data's where-about in physical medium. Also, back up requires reconstruction of the logical disks as contiguous disks so that they can be used in a traditional manner, but it is a time consuming job.

2.     Interoperability and vendor support: Various developers said that for any virtualization software, the interoperability between the operating systems, software and connectivity hardware is must. But, the service providers may not support other's apps and services therefore users can have problem of any shift on new software or other vendor's services.

3. Complexity: Due to the management of abstraction layer, which is required to hide the implementation details of a particular set of functionality, the system becomes much complex. Hence, IT managers find difficulty in problem determination and fault isolation, and also create issue of latency.

4. Meta-data management: The prime concern for any organization is its data storage and retrieval. Therefore, meta-data is the valuable asset for today's business and if there is loss of meta-data, it would be virtually impossible to reconstruct the logical drives without the mapping information. Hence, it is necessary to implement proper protection via enough backups and replicas of the information.