User guide

Understanding Drive Arrays D-11
Concurrent I/O Request Servicing
The Smart Array 431 Controller has the capability to service hundreds of I/O
requests at a time. For example, if you request data that resides on the first
drive and another user requests data that resides on the second drive, the
controller can deliver both pieces of information concurrently. Figure D-8
illustrates concurrent request servicing.
User 1
Request
User 2
Request
User 3
Request
User 4
Request
Figure D-8. Concurrent Request Servicing handles several I/O requests
Optimized Request Management
Optimized request management, also known as elevator trend sorting, is
another performance enhancement feature provided by the Smart Array 431
Controller. The controller receives and queues multiple data requests from the
operating system. The controller then rearranges the requests in an order that
optimizes performance.
Consider the following example. The Smart Array 431 Controller receives a
request for a physical drive that is not currently active. The controller
schedules the request immediately ahead of previously received requests
already queued to other active drives within the array. This request
management process operates concurrently with drive operations. The benefits
of optimized request management increase as greater demands are made on the
drive subsystem.