Living the Storage Consolidation Dream, Part II

The dream of storage consolidation for distributed systems is closely patterned after the model that was established early-on in mainframe environments. Companies anticipated achieving the same financial and technical benefits in their distributed environment that occurred when they consolidated their mainframe environments. Yet as these consolidations occurred, companies find a disconnect between what end-users in distributed environments expect in terms of storage management flexibility after the consolidation is complete and what those in mainframe environments expect.

End-users in distributed environments expect to retain the same privileges of self-service storage (freedom to make changes, provision storage and manage applications) as they did prior to the storage consolidation. However end-users can loose this flexibility and freedom to manage storage themselves unless they pick a storage system that is specifically designed with the internal virtualization capabilities to accommodate these expectations. To do so, companies need to look beyond storage providers that initially designed their storage systems for mainframe storage consolidations and later retrofit them for distributed, open system storage consolidations. Instead they need to select systems that are intended more specifically for virtualization-based storage consolidations.

In these circumstances, companies may be better served by considering a next-generation storage system like the 3PAR InServ Storage Server. It mirrors other enterprise storage systems in that it provides large numbers and different types of storage connections (iSCSI - 32 ports, FC - 128 ports), processing power (up to 8 controller nodes) and large amounts and varying tiers of storage capacity (up to 600 TB). Where 3PAR distinguishes itself from other enterprise storage systems is through the Virtual Domain feature found on its InServ Storage Servers.

Virtual Domains preserve the storage management freedom that departments and business units were accustomed to prior to consolidation of their application data on shared storage systems. It resembles a similar concept in server virtualization, the virtual machine, in that each Virtual Domain is administratively secure and appears to the user as a dedicated (virtual) array.  However each Virtual Domain leverages the massively parallel resources of the InServ, delivering higher performance per domain than would otherwise be available on a dedicated system.  Like virtual server environments, each Virtual Domain operates independently of other Virtual Domains so after the consolidation is complete, individual departments or business units can be assigned one or more Virtual Domains which they then have full authority to manage as they best see fit.

Each Virtual Domain offers all of the storage management functions that the underlying 3PAR InServ Storage System offers, including thin provisioning, snapshots and the creation of storage volumes with guaranteed service levels. Capacity thresholds can also be assigned to each Virtual Domain by storage tier.  However since each Virtual Domain is its own separate, logical entity, if an Virtual Domain administrator makes a configuration change that results in an error, only servers attached to that Virtual Domain are potentially impacted. This differs from other consolidation environments where any configuration mistake could ripple out to impact any server attached to the storage system.

Virtual Domains should also not be confused with hard partitioning which is employed on some systems. Hard partitioning divides and dedicates specific hardware resources (controllers, memory, storage, port connectors) into partitions within the storage system. The challenge with this approach is that once the partitions are set, the resources are pre-dedicated to that partition and utilization suffers - particularly where performance is a consideration and large numbers of disks must be pre-dedicated to physical partitions to meet certain service levels.

Using Virtual Domains, all Virtual Domains on the storage system have access to all hardware resources and are distributed across them. This gives administrators the flexibility to configure resources within and across Virtual Domains as application demands fluctuate over time and prevents over- or under-allocation of resources which can occur when hard partitioning is employed.

Storage consolidation is a dream that many companies are seeking to realize but what they often find is that the reality of consolidation does not match its promise. The Virtual Domain feature on 3PAR's InServ Storage Systems changes that. It takes the concept of server virtualization that is already known and understood and applies that to its storage system. In so doing, corporate business units and departments can, post-consolidation, retain the storage management flexibility and freedom to which they are accustomed while companies can realize the technical and financial benefits of consolidation that they initially sought when they implemented it.

Part 1 in this series examines some of the hidden, intangible costs of consolidation once the consolidation process is under way.