The most popular applications for cloud storage are long-term retention of archives and as a lower-cost alternative for storing lower value data. Public and private cloud storage systems are just now becoming a standard part of the IT arsenal. However, conventional applications may not be able to access the unique interfaces common to many cloud storage services and products. This has given rise to a new class of cloud storage gateway applications that ease the transition by presenting cloud storage in a way that applications can use.
What's wrong with cloud storage systems?
An important differentiator between modern cloud storage and the managed storage of years past is the API-based interface used by many cloud systems. Rather than using a conventional SAN or NAS protocol, most public cloud providers rely on Internet protocols, using a REST API over HTTP. This is wonderfully useful for today's programmers, but totally incompatible with legacy applications.
Even if a conventional storage protocol is used, most cloud storage systems are engineered more for scalability than absolute performance. Off-site services must contend with network latency in addition to any architectural choices made in favor of flexibility. This means that, regardless of the interface used, a cloud storage gateway can be beneficial or even a downright requirement
Another consideration is the unique security model associated with most cloud storage services. Access to block storage is usually controlled by region, for example using LUN masking to restrict access to a single host bus adapter (HBA) on a single server. Above this lies the file system, which controls access based on users, groups and directories in a tree. Cloud storage systems use an entirely different security model, one based on tenants, buckets and the objects. Although potentially more flexible, the cloud security model is entirely incompatible with conventional systems.
Enter cloud storage gateway vendors
A number of cloud storage gateway products have recently appeared to ease the transition between conventional and cloud storage interfaces. Each product focuses on a unique touch point between applications and their storage. Cloud gateways can make cloud storage appear to be a NAS filer, a block storage array, a backup target or even an extension of the application itself.
- Asigra Inc. produces an integrated backup solution for public and private cloud storage services with integration both on-site and at the service provider location.
- Cirtas Systems produces the Bluejet cloud storage controller, which allows public cloud storage services to be accessed as if they were on-site block storage arrays.
- Nasuni Corp. produces a virtual appliance that acts as a file server, complete with snapshots, caching and encryption.
- StorSimple Inc. produces a storage appliance with caching and provisioning, deduplication, encryption and WAN optimization targeted at SharePoint implementations.
- The TwinStrata Inc. CloudArray is a data protection and disaster recovery appliance integrated with public cloud storage.
- Other companies, like CommVault Technologies Inc. and Symantec Corp., have integrated cloud storage as a backup target on par with tape and disk.
The common theme for all these products, beyond bridging local applications to remote cloud storage, is the value-added features they introduce. Most include encryption technology to safeguard data stored off-site, as well as compression, deduplication and WAN optimization technology to accelerate performance. Many also take advantage of the scalability of cloud storage for features like snapshots, version control and data protection. And in nearly every case, local storage is used as a cache for improved performance.
Is cloud data storage a tier?
Although it's tempting to see the integrated storage provided by these gateways as part of the overall trend toward tiered storage, cloud data storage can be much more than a low-cost tier. Indeed, each of these applications also demonstrates that the unique capabilities of cloud storage can provide new functionality previously unknown in conventional storage systems. Each cloud storage gateway vendor is blazing a new trail, bringing new capabilities rather than merely lowering the cost of storing data.
BIO: Stephen Foskett is an independent consultant and author specializing in
enterprise storage and cloud computing. He is responsible for Gestalt IT, a community of
independent IT thought leaders, and organizes their Tech Field Day events. He can be found online
at GestaltIT.com, FoskettS.net, and on Twitter at @SFoskett.
This was first published in November 2010