The present invention relates generally to storage controllers and, in particular, to managing system resets caused by host adapter errors.
A large-scale computing system generally includes a storage controller, such as the IBM® Enterprise Storage Server®, which processes input/output (I/O) commands from one or more host devices, such as an IBM S/390®, to write data to or read data from one or more storage devices, such as hard disk arrays, storage libraries or the like. Such controllers include error handling routines to process errors in the various I/O adapters through which external devices, such as hosts, servers and storage devices are attached to the storage controller. Although many errors may be “cleared” by resetting error registers in various components within the controller, there are many other types of errors which require a hardware reset in order to recover from the error.
As will be appreciated, a hardware reset is time consuming and very disruptive to host operations. In a typical prior art recovery process, directed by an error handler, microprocessor code must be reloaded and built-in self-tests and power-on self-tests must be run before registers may be initialized. Moreover, global structures which are shared and exchanged with other processors must be updated.
Consequently, a need exists for a less disruptive error recovery process in a device such as a storage controller.
The present invention provides methods, systems, computer program products and methods for deploying computing infrastructure for processing adapter errors. Rather than executing a disruptive controller hardware reset, an error handling routine provides instructions for a reset operation to be loaded and executed from cache while the SDRAM is in self-refresh mode and therefore unusable.
The memory controller 120 includes, among other components, an error register 122 and a cache controller 124. The processor 130 includes, among other components, an error register 132 and an L1 cache 134. An L2 cache 136 may be on-board, as illustrated, or external to the processor 130.
Referring also to the flow chart of
Simultaneously, the SDRAM 108 performs its internal refresh operation. Upon completion of the refresh, reset function code directs that the configuration and interface registers 126 and 128 in the memory controller 120 be refreshed or initialized (step 210). Finally, when the configuration and interface registers 126 and 128 and SDRAM 108 are initialized, processes are released and allowed to access the SDRAM in accordance with normal operations (step 212).
It is also no longer necessary to run the power-on self-tests or built-in self-tests. Consequently, disruptions to host operations are significantly reduced and normal I/O operations may resume more quickly.
It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciated that the processes of the present invention are capable of being distributed in the form of a computer readable medium of instructions and a variety of forms and that the present invention applies regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media such as a floppy disk, a hard disk drive, a RAM, and CD-ROMs and transmission-type media such as digital and analog communication links.
The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. Moreover, although described above with respect to an apparatus, the need in the art may also be met by a method of managing memory controller reset, a computer program product containing instructions for managing memory controller reset, or a method for deploying computing infrastructure comprising integrating computer readable code into a computing system for managing memory controller reset.