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.