Storage virtualization separates the storage-management software from the underlying hardware infrastructure in order to provide more flexibility and scalability. This can be used to create flexible and scalable pools of storage resources.
Storage virtualization is a technique to abstract information about all of the storage hardware resources on storage area networks (SANs). This can be used to integrate hardware resources from different networks and data centers into one logical view.
SAN in the Cloud
In its “Storage Virtualization Tutorial,” published in 2001, Storage Network Industry Association (SNIA) has made an effort to describe important characteristics of storage virtualization.
The group first defined storage virtualization as such:
- The act of abstracting, hiding, or isolating the internal functions of a storage (sub) system or service from applications, host computers, or general network resources, for the purpose of enabling application and network-independent management of storage or data.
- The application of virtualization to storage services or devices for the purpose of aggregating functions or devices, hiding complexity, or adding new capabilities to lower level storage resources.
(Source: SNIA – www.snia.org)
Storage virtualization has been used over the years to solve many of the challenges in scaling and managing large amounts of storage, a challenge that has only increased as the amount of data increases exponentially. Virtualization can be used to improve scaleability, redundancy, performance, and economics.
Many different technology techniques can be used to virtualize storage functions. These can include masking, zoning, use of host-bus adapters, creationg of logical volumes, RAID, and the use of distributed file systems or objects. All of these techniques require an underlying storage hardware, typically consisting of arrays of disks, flash memory, or a combination thereof.
Virtualization can aggregate and manage data across a wide range of physical assets in large networks or data centers. This data can be aggregated to isolate performance issues, predict and troubleshoot problems, and plan for future capacity needs.
While benefits of storage virtualization are substantial, there are many technical hurdles. The main challenge is that storage environments are heterogenous environments with many different hardware and software components, often supplied by many different vendors. For example, storage management software, operating systems, file systems, network management interfaces, and storage hardware devices are all involved in the building of a storage system. In addition, the demanding nature of today’s applications, which consume ever-increasing amounts of data in shorter amounts of time, mean that storage systems need to be ready for consistent and rapid upgrades.
By virtualizing storage, a system can be made more scalable because commodity hardware can be quickly snapped in and discovered by the virtual software system. These hardware resources can then be added to a virtual pool of storage that is available to the virtual system. This has driven one of the largest trends in the storage industry, which is a “scale out” approach in which hardware capacity can be added quickly in a modular fashion.