Web 2.0 and small businesses have been among the early adopters of external cloud storage, which allows customers to use their applications without having to buy expensive equipment or hire large IT staffs.
While an internal cloud's infrastructure sites inside the data center, an external storage cloud is hosted by a service provider located outside the data center. Like internal clouds, external clouds can be public or private. Public external clouds are shared by many, while private clouds are usually dedicated to one customer and hosted at the service provider's facility.
External public clouds often require developers to port applications to application programming interfaces (APIs). These clouds are frequently accessed using standard data storage and network interfaces or middleware provided by a cloud service provider. While external public clouds make it possible to use resources for just minutes at a time, external private and "community" clouds are more often used for longer-term replacement of an existing data center resource.
Smaller companies find it easier to move to external storage clouds because they have less of an infrastructure to migrate to an external service provider's cloud and less IT expertise than larger enterprises.
External public clouds
The best-known cloud storage applications are offered by Amazon, Google and others such as Rackspace Inc. and Nirvanix Inc. who use the same model. So far, these services have appealed mostly to other Web companies. Photo-sharing site SmugMug Inc. and social networking service Twitter use Amazon Simple Storage Service (S3), while a Twitter-related photo-sharing company called TweetPhoto Inc. uses Rackspace's Cloud Files.
TweetPhoto turned to Cloud Files when it started up last year. TweetPhoto co-founder and CEO Sean Callahan said his company is more concerned with sticking to developing its application and business model than architecting data storage. "We eventually expect millions of people to come to the site," he said. "We want to pay for what we need on-demand."
Public cloud storage services have had high-profile outages in the last couple of years, including an Amazon S3 crash that brought Twitter down. But Callahan said he trusts Rackspace's infrastructure. "They're a publicly traded company, and as a company their focus is solely on computing," he said.
Other Web companies have jumped on public cloud storage offerings from Nirvanix, which emerged in the fall of 2007 claiming it could overcome the performance issues reported by some large Amazon S3 users.
External private clouds
Vineet Jain, CEO and founder of cloud network attached storage (NAS) vendor Egnyte Inc., said his company's focus has been on eliminating file servers for companies with up to 1,000 employees. So far, Jain said most of his customers are at the low end of that range, approximately 10 employees. The company has grown a customer base of tens of thousands out of that market segment.
"No matter how small or big you are, people are still wary of living on someone else's cloud, and they want offline access to data. Also, editing large objects over the network does incur some latency," Jain said.
For these reasons, Egnyte offers a "hybrid" cloud storage product, one that pairs internal copies of data with those located in the cloud. Egnyte offers two versions of its on-premise software agents. One version makes a "local cloud" out of internal desktop or laptop storage, while the other allows customers to use a local NAS device synched to the cloud.
Egnyte customers say a "filer in the sky" was easier and cheaper than deploying their own internal NAS and network to share files. Joel Parsons, curatorial and marketing assistant at the Memphis-based National Ornamental Metal Museum, said his organization began using Egnyte's workstation-based local cloud software approximately a year ago to share files among staff creating a monthly newsletter.
The museum needed an easy means of sharing large digital files across Windows and Mac operating systems. "A major factor [in choosing Egnyte] was the ease of use –we needed a clean, clear interface," Parsons said. Museum users can work on files within Egnyte's Web portal, so they don't take up storage space on local machines.
Michael Steller, principal and president at Cynergy Financial, a five-person financial services provider located in Pleasant Hill, Calif., said Egnyte made his job much easier. "I'm a salesman and a tax financial planner," he said. "I work seven days a week and spend a lot of time on the road – I'm almost never at the office. Once a week I'm at home at night and invariably, a phone call comes from a client."
Previously, Cynergy had used a Citrix Systems Inc. application called GoToMyPC, which allowed Steller to login to his office desktop. "It required a 30-second process to get there every time, and I was uncomfortable working on files knowing that if there was a network blip, my work might not get saved," he said.
Steller developed the habit of downloading files from the office to his home PC and transferring them back when he was done working with them.
Egnyte synchs files among the PCs connected to the local cloud automatically every 15 minutes. "I was at home [recently] and a client called. I needed an 18-page financial plan -- boom boom, open and done," Steller said.
Larger enterprises take cautious approach
Larger organizations with existing IT infrastructures are more cautiously evaluating external clouds and public clouds for specific applications. David Grant, a data center manager with a large communications company he requested not be identified, said colleagues are beginning to investigate porting particular applications such as email into an external public cloud service. He said an external service provider could help the company do "things we can't do currently that we'd like to do, like a comprehensive archiving strategy."
Brad Blake, director of infrastructure and engineering at Boston Medical Center, said his organization has also been considering putting applications such as antivirus and spam scanning or email into an external public cloud. But he said there are privacy and reliability issues.
"Every few years when we do an Exchange or SQL upgrade, we look at software as a service, but for one reason or another, we don't go for them," he said. "From a hospital and privacy perspective, I'm not keen on having servers sit on a shared infrastructure."
Recently, Blake said his organization was evaluating Google's Gmail and Postini archiving, but the Postini service suffered a significant outage in October that Blake said gave him pause. "Again, we have to weigh what's moving out there and what happens in that case," he said. "With email, you can re-point [a mail server and still have communications], but to take a clinical system out like that is a major issue for a hospital."
(Tomorrow: examing internal clouds)