July 2014 Archives

Death of the LUN: Another nail in the coffin from Gridstore?

Antony Adshead | No Comments
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Has the LUN had its day? It has been the de facto method of creating logical volumes on physical storage for decades, but in this era of virtualisation that may be becoming a thing of the past.

In VMware or Hyper-V environment the LUN still exists but only as a single large pool in which the virtualisation platforms' virtual drives are created.

But Gridstore, which substitutes so-called vLUNs for LUNs while providing storage for Microsoft Hyper-V virtual machines, claims to have done away with the LUN altogether, in something like the way Tintri does for VMware environments.

Gridstore combines storage arrays largely comprising cost efficient 3TB or 4TB SATA drives and MLC flash (500GB or 1TB in its performance nodes) with software that lives in Microsoft System Center

That software comprises a "vController" that matches Hyper-V virtual machines to vLUNs and provides quality of service (QoS) on storage provision. The vController, Gridstore says, emulates the single app-single server-DAS setup of the physical server world with data put in queues and sent in bursts rather than randomly as they occur.

"Virtual environments and the LUN are an architectural mismatch," says George Symons CEO at Gridstore, which makes scale-out array nodes in 12TB and 48TB base units, expandable to petabytes.

"A LUN must cater to many servers of different types of workload and are the site of the I/O blender effect", he says, referring to the way many and random I/O requests from virtual machines can overload physical storage.

In Gridstore arrays the vController can match storage performance to the needs of the VM, should that be sequential or random and can make sure "noisy" virtual machines do not disrupt others, alerting the admin if a VM isn't getting the gold, silver, bronze levels of performance set.

Gridstore claims 40,000 IOPS for the minimum three-node configuration of its 12TB devices. It doesn't sound a lot, when you think of the 500,000 and 1 million IOPS boasted by the all-flash provider.

But you don't need that, says Symons. "They talk of one and two million IOPS but 40,000 IOPS covers the needs of most people. To be honest most customers don't know what they need and most are in the 1,000 IOPS to 5,000 IOPS range. But in any case we can scale to 100,000 IOPS on nine nodes.

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