Making the Case for Cloud Storage

Storage is often cited as one of cloud's killer apps because it provides quick and easy access to data as an temporary cache, a long-term archive and, best of all, a much faster way to reboot your business in the event of an outage -- all without trucks and tape.

By Paul Rubens | Posted Apr 2, 2012
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The cloud is rapidly emerging as an ultra-low cost, flexible and highly scalable storage resource, and it's this type of usage, rather than running applications in the cloud, that's catching the interest of many enterprises.

The attraction of cloud storage is not hard to understand because it  can be used in a variety of ways. The most popular ones are:

Overflow capacity - Cloud storage can provide short term storage capacity to cope with occasional spikes in demand for storage, or to provide storage as an interim measure before new on-premises storage devices come online. For performance, network latency and reliability reasons it is rare for this type of overflow capacity to be used to store current data being processed by applications.

Archive storage - Cloud storage provides a lower-tier storage option  for older data that organizations may need to retain for many years for compliance purposes or for future analytical purposes, but may rarely or never be accessed. Moving this type of data to cloud storage frees up more expensive tier-one storage resources for everyday use by on-premise applications.

Backup and disaster recovery - Cloud storage provides an ideal off-site location to store backups, eliminating the need for tape handling. Disaster recovery (DR) can be achieved by sending backup data back to the original site, to an alternative DR site, or even by spinning up virtual machines at the cloud storage provider's data center and using the backed-up data in the cloud.

Of these use cases, the most popular is probably backup and disaster recovery, according to Laura Dubois, an IDC analyst. In particular, it is popular with smaller firms with less storage capacity or larger firms backing up their remote branch offices and endpoints, she said. The key attraction is that it removes the need to have backup tapes collected and stored in secure vaults offsite.

"Firms need to pay a third party to transport the tapes to the secure vault and to store them.  The cost is not trivial," Dubois said.  "Then there is risk of compromise to the tapes with the media changing hands. And if you need to recover, the tapes need to be found and transported to the place of recovery.  Depending on where they are stored that could take hours, be done overnight or take days."

Cloud storage gateways

To use cloud based DR, many companies are looking to cloud storage gateways: software or appliances, either physical or virtual, which translate cloud storage APIs to block-based storage protocols like iSCSI and Fibre Channel or file-based interfaces like NFS and CIFS. With a cloud storage gateway installed on premises, they can continue to use their existing backup applications, using the gateway as a target.

Riverbed's Whitewater cloud storage gateway is designed exactly for this purpose. Targeted at medium sized enterprises, a Whitewater appliance (either physical or virtual) talks to a data protection or backup server and accepts the backup data. The appliance then carries out deduping, compression and encryption before caching the most recent backups, and replicating the data to a cloud storage provider such as Amazon. The deduping and compression leads to an average reduction in the data that needs to go to the cloud of about 25:1, or about four percent of the original data, according to Ray Villeneuve, Riverbed's Whitewater general manager.cloud computing icon

In the event that data needs to be restored, the relevant data will often be found in the Whitewater appliance's cache. If not, it can be restored from the cloud through the Whitewater. For DR purposes organizations can use a standby Whitewater appliance at an alternative site or simply download and bring one up as a virtual appliance. They can then begin to download data or mission critical subsets of the data to "rehydrate" the replacement Whitewater appliance, which then passes the data back to the backup application.

Villeneuve sees this use case as the most natural for Whitewater appliances at the moment, but expects them to be used for archiving more in the future. "Our appliances are optimized for back up [of] a small number of large files. But we are aware of the archiving use case; a workload characterized as more random I/O. In the future, we will add features to enable that, although we have some customers using it for that purpose already."

Dubois agreed. "The majority of mid-market customers still do their archiving/long term retention of data through their back up application policies.  So, yes this would be feasible.  But firms need to factor in the recurring service costs of keeping data in the cloud versus the capital and op-ex costs of keeping it onsite. "

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