Systems, methods, and computer products that improve the performance of computer-implemented I/O operations issued by complex applications that are directed to high-performance disk drives, and that may operate in conjunction with the product marketed under the trademark IBM S/390.RTM.. Such high-performance disk drives may include the IBM Shark.RTM. that supports the parallel access volumes feature.
CROSS-REFERENCE TO RELATED APPLICATION
In co-pending application Ser. No. 10/033,810, entitled "Systems, Methods, and Computer Program Products to Improve Performance of Ported Applications, such as a Database," filed on the same date herewith, by William E. Malloy, et al., assigned to the assignee of the present invention, and incorporated herein in its entirety by this reference, there is described a method of bypassing the general-purpose I/O caching features of a computer system in favor of the specialized I/O caching features of the application. Although not limited thereto, the present invention employs such a method in one of its preferred embodiments.
In co-pending application Ser. No. 10/033,809, entitled "Systems, Methods, and Computer Program Products to Improve Performance of Ported Applications, such as a Database, Operating on UNIX System Services for the OS/390," filed on the same date herewith, by William E. Malloy, et al., assigned to the assignee of the present invention, and incorporated herein in its entirety by this reference, there is described a method of bypassing the general-purpose I/O caching features of the UNIX System Services for the OS/390 in favor of the specialized I/O caching features of the application. Although not limited thereto, the present invention employs such a method in one of its preferred embodiments.
Methods and associated structure for utilizing multiple ports or PHYs comprising a SAS wide port to improve transmission bandwidth utilization for a single large I/O request. In one aspect hereof, a large I/O request is broken into a plurality of smaller I/O requests to be distributed over multiple PHYs or ports of a configured wide SAS port. The number of smaller I/O requests may be any number up to the maximum number of PHYs or ports comprising the SAS wide port. In another aspect hereof, the size of a large I/O request may be compared against a threshold value to determine whether the large request should be broken into smaller requests. The threshold value may be determined in accordance with features and aspects hereof either statically or dynamically based on workloads assigned to, and utilization of, the configured SAS wide port.
In a data storage system having a drive I/O command queue associated with a data storage device, contiguous I/O requests of at least a predetermined size may be processed in a pipeline mode of operation by issuing to the command queue a plurality of contiguous I/O request portions, each comprising a portion of the I/O request, so that a next one of the I/O request portions is in the command queue before the data storage system completes a current I/O request portion. The data storage device may implement I/O reordering based on data location and contain at least two device I/O command queues or, alternatively, may not implement such reordering and contain a single command queue. In one embodiment, a performance parameter of the data storage system, such as the bandwidth requirement for the contiguous I/O request, is monitored and the size of subsequent I/O request portions and/or the state of the pipeline mode of operation are adjusted accordingly. With this arrangement, large contiguous I/O requests can be executed at a higher bandwidth, without adversely impacting other I/O requests for the same device.
