Virtualization Putting DAS Back in Play


What's old is now new and what's new is -- well, I don't remember how the rest goes, but the first part of the saying is very appropriate to direct-attached storage these days.


It seems that more and more enterprises are coming to the realization that virtualization and SANs, while offering a number of advantages, particularly to large organizations, is a pain in the patukus to manage. So a number of people have been reverting to good ol' DAS to simplify things a bit.


Paul Shread over at Enterprise IT Planet took a look at this trend a few days ago, noting that, if done right, direct-attached SAS designs can even improve efficiency and flexibility in many environments. He notes that HP recently unveiled a new SAS storage option for the BladeSystem line capable of scaling up to 192 TB across as many as 32 blades. The package consists of the StorageWorks 3 Gbps BL SAS switch, the P700m Smart Array Controller and the MSA2000sa array.


The goal, according to Lee Johns, HP's director of marketing for entry-level storage, quoted here on Infostor, is to offer the advantages of shared storage without the cost and complexity of a full-fledged SAN. Each MSA module has one controller and three disk trays that hold up to 12 1 TB SATA drives and can service all the blades in a C7000 and C3000 enclosure.


For those who can afford it, though, a good management stack can make the complexities of a SAN worthwhile, according to George Crump of Storage Switzerland. Once you're on the virtualization fast track, a key requirement is the ability to see the interaction between storage, VMs and their physical hosts, allowing you to choose the most available storage, processing and I/O resources. Sure, it's complicated, but at least you know you're getting the maximum use out of your enterprise infrastructure.


Nonetheless, low-end customers are calling for DAS, so it aims to please, says Mike Young, CEO of storage designer Sullego. The company recently unveiled a new DAS-friendly virtualization server, the ES100, for customers only looking for basic storage. As he says:

Today's DAS solutions are cheap, roughly sub-$2/Gbyte. But they also represent monolithic, fixed-featured investments. They don't back up. They don't replicate. They don't run virtual machines. And the list goes on. We wanted to provide a solution for our customers, priced as low as $1/Gbyte. And when they exhaust the capabilities of it, they can simply buy another and another. As their needs grow, these servers can be parallel-clustered to scale both capacity and performance.

As an old friend from my days covering video-production technology told me once:

You may have the most advanced technology in the world, but trying to get customers to buy something they don't want is like trying to push on a rope.