Browse Prior Art Database

In-line Processing Commands for Storage Devices

IP.com Disclosure Number: IPCOM000119690D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 9 page(s) / 315K

Publishing Venue

IBM

Related People

Bandy, PB: AUTHOR

Abstract

A special-purpose state machine is placed inline between a storage device and the host system to perform Inline Processing commands. The host system can offload simple, highly redundant processing functions, such as contextual searches, logical data selection and reformatting. In addition to reducing the demand for host system processor and memory resources, the offloaded processing is performed at the sustained data rate of the storage device so that very large increments of data can be processed in a single sustained operation, allowing more efficient utilization of the storage device.

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In-line Processing Commands for Storage Devices

      A special-purpose state machine is placed inline between
a storage device and the host system to perform Inline Processing
commands.  The host system can offload simple, highly redundant
processing functions, such as contextual searches, logical data
selection and reformatting.  In addition to reducing the demand for
host system processor and memory resources, the offloaded processing
is performed at the sustained data rate of the storage device so that
very large increments of data can be processed in a single sustained
operation, allowing more efficient utilization of the storage device.

      Inline Processing Commands can be implemented for a variety of
storage devices and device configurations. Storage devices might be
Direct Access Storage Devices (DASD), magnetic tape, flexible
diskette drives, optical storage devices, etc.  Fig. 1 illustrates
several configurations of Inline Processing Commands.

      Inline Processing Commands are implemented using a
special-purpose state machine to process data that is being read from
a storage device.  The most natural and economic implementation is
incorporating the state machine within the storage device controller
as illustrated in integrated controller configuration (a) or the
common controller configuration (b) of Fig. 1.  In these
configurations the Inline Processing operations are performed
directly on the data in the read buffer.

      Inline Processing Commands can also be retrofitted to existing
storage devices and controller products by the more costly non-
integrated configuration illustrated configuration (c) of Fig. 1.  An
add-on interposer product is inserted in the interface between a
controller and a host system attachment.  The interposer product is
functionally transparent until the host system issues an Inline
Processing Command.  The Inline Processing interposer issues the
standard read command to the storage device and processes the data as
it is received.

      Since Inline Processing Commands are extensions to the
conventional storage device commands, the following description
assumes reader knowledge of basic controller design and operation.
The extensions required to a conventional controller include the
addition of microprocessor tasks to support command decode, state
machine initialization and control and changes in buffer allocation
and controls.  The effected controller components are shown in Fig. 1
where the controller consists of a microprocessor and memory, both
required by conventional design, and the inline processor state
machine which performs the Inline Processing Commands processing
operations.

      Other conventional controller components, such as the host and
storage device interface control hardware, are functionally unchanged
and therefore not shown for the sake of simplicity.  The design of an
interposer product would have the same basic components plus the
log...