Usage Models

Intelligent Adapters

Intelligent adapters are typically peripheral devices that use a local processor to offload tasks from the host. Examples of intelligent adapters include RAID controllers, modem cards, and content processing blades that perform tasks such as security and flow processing. Generally, these tasks are either computationally onerous or require significant I/O bandwidth if performed by the host. By adding a local processor to the endpoint, system designers can enjoy significant incremental performance. In the RAID market, a significant number of products utilize local intelligence for their I/O processing.

Another example of intelligent adapters is an ecommerce blade. Because general purpose host processors are not optimized for the exponential mathematics necessary for SSL, utilizing a host processor to perform an SSL handshake typically reduces system performance by over 90%. Furthermore, one of the requirements for the SSL handshake operation is a true random number generator. Many general purpose processors do not have this feature, so it is actually difficult to perform SSL handshakes without dedicated hardware. Similar examples abound throughout the intelligent adapter marketplace; in fact, this usage model is so prevalent that for many applications it has become the de facto standard implementation.

Host Failover

Host failover capabilities are designed into systems that require high availability. High availability has become an increasingly important requirement, especially in storage and communication platforms. The only practical way to ensure that the overall system remains operational is to provide redundancy for all components. Host failover systems typically include a host based system attached to several endpoints. In addition, a backup host is attached to the system and is configured to monitor the system status. When the primary host fails, the backup host processor must not only recognize the failure, but then take steps to assume primary control, remove the failed host to prevent additional disruptions, reconstitute the system state, and continue the operation of the system without losing any data.

Multiprocessor Systems

Multiprocessor systems provide greater processing bandwidth by allowing multiple computational engines to simultaneously work on sections of a complex problem. Unlike systems utilizing host failover, where the backup processor is essentially idle, multiprocessor systems utilize all the engines to boost computational throughput. This enables a system to reach performance levels not possible by using only a single host processor. Multiprocessor systems typically consist of two or more complete sub-systems that can pass data between themselves via a special interconnect. A good example of a multihost system is a blade server chassis. Each blade is a complete subsystem, often replete with its own CPU, Direct Attached Storage, and I/O.