NetApp storage efficiency guarantee debunked

NetApp launched its Storage Efficiency Guarantee as a means of demonstrating the disk-saving potential of virtualisation technology.

Phase one of the guarantee, announced in September 2008, guaranteed NetApp customers data storage savings of at least 50 per cent using NetApp de-duplication on NetApp hardware.

If an organisation didn't gain at least 50 per cent savings, NetApp offered the difference in free storage hardware.

Phase two, announced in February, extends the guarantee to specified third party hardware from EMC, IBM, HP, or Hitachi Data Systems.

Organisations running NetApp data de-duplication software on specified third party hardware are promised 35 per cent storage savings, or again, NetApp will make up the balance with its own hardware.

But a closer look at the conditions of the guarantee spoil the story somewhat, according to EMC Australia's VMware business manager, Darren McCullum.

McCullum points out that among the conditions is a requirement that the customer is migrating from one of the most conservative RAID (redundant array of independent disks) configurations - RAID 10.

Sometimes referred to as RAID 1+0, this configuration sees an organisation deploy twice as much disk as it uses, in order to ensure data is not lost should a single disk fail.

NetApp's guarantee only applies to those organisations moving from RAID 10 to its own proprietary RAID configuration, RAID DP, which requires far less disk.

It is not hard to see how an organisation that needed two 40GB disks (80GB) for only 40GB of useable space would halve their data storage requirements overnight by moving to a configuration that did not require so much redundant disk.

"Anyone moving from RAID10 to RAID-DP is going to get instant savings," admits Michael Delandere, systems engineering manager for NetApp Australia.

"So yes, a considerable chunk of the savings will come from the switch in RAID configuration itself. But we are saying, here is a way to make considerable savings and we will stand by it."

The NetApp guarantee also insists that no more than ten per cent of the total data set being de-duplicated can be graphics, XML, database data, Microsoft Exchange data or encrypted data.

This effectively excludes from the guarantee some of the most data-intensive areas of any organisation and leaves little else but file servers applicable.

"There are certain applications where moving the dial towards saving footprint isn't in the best interests of the customer," says Delandere.

"The guarantee shouldn't apply to applications with a higher I/O load."

The conditions defeat the purpose of what a customer should hope to achieve with virtualisation beyond consolidation, says McCallum.

"Virtualisation offers a new way of doing things, in terms of flexibility, how you deliver services," he said.

"The conditions you have to meet for the guarantee are so onerous they fly in the face of the reasons you would virtualise in the first place. It is very short-sighted."

But Delandere insists the guarantee offers assurance for customers considering the latest storage and virtualisation technologies.

"These [conditions] are not things we are trying to hide under the covers," he said, pointing to NetApp's detailed documentation published online.