The intensified demand for IT network efficiency, increased application performance and lower operating costs have been driving the phenomenal growth of virtualization in the past decade, with no signs of slowing. At present, many organizations run more virtual servers than physical servers.
In order to understand VM storage performance, we first need to understand what storage virtualization is. Storage virtualization involves the creation of a usually very large, logical-pool of data. Via software, that pool appears to be physically located all on one server. In actuality, that data may be located across hundreds of physical disks spread across dozens of servers. This is the concept implemented by Storage Area Networks (SAN).
This technology essentially abstracts “logical storage” (what the OS sees and uses – i.e., the file system) from physical storage (the striped RAID sets). The key differentiator in virtual storage is that the multiple physical storage devices (e.g. a RAID array) are combined into one large grouping, on top of which a virtual storage container is created.