The success of VMware as the preferred platform for server virtualisation has renewed interest in storage virtualisation.
Storage supplier 3Par has benefitted from the demand, according to CEO David Scott, who says businesses are looking for the thin provisioning of storage.
Thin provisioning overcomes a limitation with the normal way of allocating storage. Instead of having to allocate storage up-front for the maximum size of database an application will require, 3Par's thin provisioning allows a storage manager to grow storage partitions as and when required.
He says, "In our approach, people do not have to buy 10Tbytes of storage up-front for empty disc space." Instead, 3Par borrows the server virtualisation model from VMware and applies it to storage. As in VMware's server provisioning, users can provision storage on the fly, he says.
Scott says 3Par is also addressing the security concerns of running multiple virtual machines on the same server hardware. "We separate different applications using virtual domains to isolate data and enable mixed workloads like database intensive applications and I/O intensive applications to run together."
He says it offers additional benefits to make 3Par a good fit for server virtualisation, especially when VMware users want to run several virtual machines using the same hardware infrastructure.
Scott says, operating system memory becomes a real problem. In modern operating systems memory used for applications and the operating system itself is copied (or paged out) to hard disk storage to make space as and when more memory is required. This is called virtual memory and allows a server to use more memory than is physically installed. On a server running several virtual machines, this copying of memory to and from a physical hard disc can take up so much time that the operating system is constantly swapping out pages of memory, leading to "page thrashing."
3Par uses disk striping, a technique for writing data across multiple disks simultaneously. According to Scott, this can reduce the chance of page thrashing.