But these financial benefits come with a non-monetary price. When one critical application runs on one physical server and one dedicated portion of shared physical storage on a SAN, the resource mix of CPU, I/O and storage can be tuned (probably manually) to provide the quality of service (QoS) for performance and capacity that the application requires during both regular processing and times of peak load demands. When multiple critical applications are commingled on the same physical server through virtualization, the situation changes as the demand for resources becomes essentially stochastic (meaning that it may not be possible to predict which applications will need I/O resources at what time). Storage, even with storage virtualization capabilities (think thin provisioning, which is actually a better capacity utilizing tool), was not designed to handle performance demands that are, for all practical purposes, unpredictable.
As a result, the performance predictability that is essential for business-critical applications cannot be guaranteed. High levels of QoS, including priority allocation of resources that mission-critical applications need to ensure that they can do their job properly, cannot be guaranteed. This has led to the slower adoption of server virtualization and lower operational benefits for these types of applications than CIOs would like.
NexGen describes the inability to provide performance predictability and guaranteed QoS levels as "the storage industry gap" and feels that existing capabilities to end the storage industry gap are either unavailable or too expensive. Now, other vendors are attempting to address these issues, such as with scale-out architectures that provide management simplicity for scale; solid state devices that consolidate performance workloads; and high-end midrange arrays that take capabilities from enterprise offerings that are moving down market.
Still, NexGen believes that none of these approaches can really address the unpredictability of performance or related issues, such as cost and complexity. Relative to storage in virtualized systems, managing capacity is easy conceptually and with the use of tools that already exist. Managing performance is a much more difficult process, since there is no easy way to provision/allocate and everything impacts everything else. NexGen feels that it has found a way out of this problem that, at the same time, has resulted in an integrated storage solution for midrange SANs.
NexGen has recently announced its NexGen n5 Storage System, which functions within what it calls an IoControl Operating Environment. This enables deterministic performance in multiple tiers of storage. The NextGen N5 Storage System provides a more or less traditional HDD active-active storage array, as we will see shortly. But it also employs ever-more-popular solid state devices on a PCIe bus for two key reasons.