Law firm Russell McVeagh added storage virtualisation capability to its storage area network earlier this year, but not for the oft-cited purpose of managing a diverse storage environment.“The main aim wasn’t to bring different platforms together,” says the firm’s network engineer, Graeme Clark (pictured). “It was to give us more flexibility in what we’ve got.”
Virtualisation allows the manager of an organisation’s storage resources to view them as one entity, rather than in terms of servers or disks. It has been described as allowing separate pieces of storage infrastructure to “become a plastic container that can be quickly and easily shaped to satisfy changing business requirements”.
The upshot is that an organisation’s storage managers aren’t dependent on the characteristics of each individual storage device, as they are able to treat the whole storage resource as one entity.
Russell McVeagh has a four-server HP SAN — a fibre channel-based network devoted to storage — and management software from the same vendor. That heterogeneous environment meant the benefits of virtualisation for ease of managing a diverse SAN weren’t applicable. However, expected demand increases and the ability to avoid downtime while adding capacity made the case for putting HP’s Virtual Replicator product on the servers, Clark says.
“We were looking to move to something where we could pool the storage more easily, without adding extra functionality and decided to go with some sort of virtualisation to expand the disk volume size on the fly.”
Clark says the firm is “only just starting down the road of consolidating its storage infrastructure”, but virtualisation makes it easy. “You just take the total disk space and slice it up for what you want.”
He says the firm hasn’t yet got to the stage where it’s putting extra storage on to it, but believes it will be easy to do so in a single format.
Virtual Replicator is installed on each of the four servers in the SAN. There are two clusters, with storage pools available to both. In each pool virtual disks are set up.
A major benefit will be the ability to add RAID sets to each pool and expand the virtual disks without disruption of service, which would be necessary if expansion without virtualisation was attempted.
A third of the disk space is occupied at present, with about 300GB of disk space utilised. The firm is looking at expanding that to a terabyte.
“Our document management system is on the SAN and there are other needs, such as archiving email.”