Metadata is yet another piece of the puzzle. ADIC, EMC, IBM, Maranti, and other vendors use metadata and metadata servers as part of their solutions as a means to aggregate application-aware storage data.
“Let’s say I have a piece of data in three places: primary storage, replicated in your hot backup location, and on tape somewhere in a vault,” says Ray Dunn, industry standards manager in the network storage division of Sun Microsystems and chair of the Storage Network Industry Association (SNIA) Storage Management Forum. “[The metadata repository] knows all three and can help you find the data when you need it. It could also say the data needs a ‘platinum’ set of services applied to it. In order for this to work well, you have to have the whole SAN — the server, HBA, anything in the fabric, the storage device, and any virtualization objects — communicating and interoperable.”
The future of metadata management for application-aware storage systems may well be object-based storage. In this model, a metadata server acts as a repository and traffic cop but the metadata itself actually follows the data across the SAN as part of a data “object.” Ideally, the business application itself would also communicate with the rest of the SAN. “The applications have to tell us what they need,” HDS’s Yoshida says.
This broad universe of application-aware storage solutions can be confusing, but it typifies the early stages of any new technology. Most vendors and analysts agree that application-aware storage would be most effective when applied across a heterogeneous SAN and to the entire data lifecycle, from creation to provisioning, migration, and disposal.
The most obvious place to start is with standards, which would provide a virtualization layer for developers to tap services without having to write to all the individual storage vendor APIs. SNIA has started the ball rolling with its SMI-S (Storage Management Initiative Specification), which covers discovery, monitoring, and some provisioning functions, but seeks to encompass services and ILM (see “SMI-S: Order from chaos”).
However, even with standards in place, setting policies and service levels cannot be done in an IT vacuum. It requires planning, consulting, and cooperation among application owners, storage managers, and the business units whose business processes are affected — not an easy task.
Widespread adoption of these ideas will take several years, if it happens at all, but the seeds of application-aware storage exist today. The standards are still emerging and a vendor shakeout is inevitable. Depending on your needs, one of these solutions may help you increase efficiencies and drive down costs in your infrastructure while assuring the service levels your applications require.