Unified storage has gone from a specialty item to something offered from nearly every storage vendor in recent years. In the beginning, vendors such as NetApp took added block capability to their file system storage and NetApp’s biggest rivals have since followed down that unified path.
The evolution continues, however, and multiprotocol systems will likely include more technological advances over the coming years.
As a refresher, I define Unified Storage as:
Unified Storage is a storage system that provides both file and block access simultaneously. The block access is accomplished through use of an interface such as Fibre Channel, SAS, or iSCSI over Ethernet. The file-based access is to a file system on the storage system using either CIFS or NFS over Ethernet.
An implied piece of unified storage is that it requires unified management, one storage system management for block and file data. Without that, the critical goal of consolidation and simplification is compromised.
Some vendors have provided block storage through both Fibre Channel and iSCSI, while others stick to iSCSI only because it is simpler to deliver. The following diagram gives a very general view that compares the implementations for block and file storage:
However, there are excellent uses of unified storage:
In a virtual server environment, a unified storage system presents an opportunity to meet demands for quickly provisioning virtual machines and meeting operational requirements. A virtual machine could be provisioned with a datastore based on NFS with its file I/O while the block storage capability of the unified storage would allow Real Device Mapping (RDM) to attach a physical disk to a virtual machine to meet application requirements.
If there is a predominance of one type of usage such as file storage for unstructured data but still there is a need for some block storage (an Exchange database for example), a unified storage system allows for consolidation to a single platform.
Unified storage provides great flexibility for an organization that needs to repurpose storage because its needs are changing.
Unified storage also provides a single resource that can be provisioned as needed for the usage type required – block or file.
But vendors haven’t just been combining block and file protocols in the same package. Recent features added to unified systems include automated tiering, solid state devices (SSDs) as a tier for higher performance, and support for cascading read/write-capable snapshots to add value for use cases such as virtual desktop infrastructures (VDIs).
What should be expected next for unified storage? It’s likely that vendors will package other capabilities together and call that the new “unified storage.” That would dilute the meaning of “unified” and require a qualifying phrase after it.