Storage Decisions: Pros and cons of cloud storage technology

A storage administrator and a storage consultant discuss the pros and cons of cloud storage during Storage Decisions sessions.

NEW YORK – While the definition of cloud storage remains in flux, enterprise data storage experts at Storage Decisions presented concrete examples of the pros and cons of using the cloud as an alternative or complement to traditional data storage networks.

Beth Israel Deaconess Medical Center (BIDMC) storage architect Michael Passe told of BIDMC's decision to add EMC Corp.'s Atmos private cloud storage alongside his traditional storage area network (SAN) and network-attached storage (NAS) systems. In a separate session, GlassHouse Technologies senior consultant Ron Scruggs provided a detailed comparison of the cloud and on-premise archiving storage.

They showed how the cloud provides a cheaper alternative, although you may have to give up performance and functionality in certain cases, and concerns remain about reliability, security and vendor commitment to the cloud model. But Passe said you can the benefits can go beyond saving money.

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"Many will ask is this really the cloud or just cheap storage?" Passe said. "Initially it may be just cheap storage, but the long-term value would seem to be in delivering multi-tenancy, policy-driven storage that can be federated internally externally or both.

"It's not for everyone right now, but you owe it to yourself to take a look at it."

Passe said the need to keep data for decades because of regulations and storing the results of medical tests with large images prompted him to look for cheaper storage. "Every day I get calls from one of the 'ologies' – radiology, cardiology – that they want to store scanned images that I didn't know about the day before," he said. "We're mandated to store them forever."

Passe divided cloud vendors into three categories: private cloud software and hardware vendors, public cloud service providers and public cloud storage application providers.

Public cloud providers include Amazon S3, Nirvanix Inc. and Rackspace Inc. Public cloud application vendors include Carbonite and Mozy for data backup, MobileMe for desktop and device sychronization, and Flickr and Snapfish for storing and sharing photos. Private cloud vendors include Bycast Inc., Caringo Inc., DataDirect Networks, EMC, ParaScale Inc. and Permabit Technology Corp.

He said benefits of a private cloud are it is controlled in-house; there's more control over security, policy-driven protection and lower costs. Concerns about the private cloud include vendor lock-in, limited NAS protocol support and vendor commitment to the cloud.

He envisions BIMDC eventually using a hybrid mode mixing private and public clouds. It will keep personal patient records on the private cloud for obvious security and compliance reasons. The public cloud can be used to replicate research data BIMDC wants to share with collaborators.

Build or rent a cloud?

Scruggs likened the choice between archiving in-house and through the cloud as "do I build a warehouse or rent space in someone else's?"

He said the cloud is a cheaper alternative to on-site archiving systems and relieves management and technology refresh concerns but there are still tradeoffs in reliability, security, and access time.

He agreed with Passe on several areas, including price, the need to scrutinize vendors, and that the definition of cloud can be hard to pin down.

Cloud storage pricing

Scruggs placed the TCO to store 40 TB for three years with a 33% annual data retrieval rate at $227,000 with a cloud provider compared to $973,000 by archiving on site. With 100 TB of data, the prices were $566,000 with the cloud and $1.475 million on site. The on-site costs included switching and off-site tape backup. The cloud cost did not include request service charge for storage or retrieval, or cost to get data to the cloud.

BIDMC is an EMC shop, and Passe broke down storage costs like this: Block data such as Exchange, SQL and Oracle go on Cisco SAN fabric and costs about $12 per GB for tier 1 on Symmetrix, and $4/GB for tier 2 on Clariion. Unstructured data is virtualized on F5 ARX switches through Celerra NAS and is backed up through Data Domain for $.50/GB or archived on Centera for $8/GB. Data stored via SOAP on Atmos costs about $.70 per GB.


Crucial issues must be cleared up before committing to a cloud provider. Scruggs and Passe said it is crucial to read service-level agreements (SLAs) carefully.

"If something happens to the data, who recovers it?" Scruggs asked. "If there's a data breach, who's at fault?"

"There are a few major providers offering SLAs that are very vague about things like guaranteed recovery and assured destruction of data," Passe said. "You want to look behind the wizard's curtain to see what is really there."

Have we been here before?

If much of cloud computing seems familiar, that's because it is. The experts advise not to get hung up on definitions.

"It's a new buzzword for an old technology," Passe said. "It's up to you to define what it means to you and what it means to your business."

"Basically the cloud is a branding of distributed computing," Scruggs said. "It's not new technology."


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