Method for enhancing host application performance with a DASD using task priorities

A method for operating a disk array storage device that processes transactions with multiple tasks of first and second categories performed in multiple logical storage devices, said method comprising the steps of:

• A) processing the tasks according to the positions of corresponding task requests in a task request queue,
• B) assigning priority to one of the logical storage devices,
• C) upon receiving a task request from any of the logical storage devices:
• i) determining the task category and the logical storage device related to the task,
• ii) transferring a task request of the first category related to the other storage devices to a position in the task request queue of a first priority,
• iii) transferring a task request of a first category related to the one storage device to a position in the task request queue having the highest priority, and
• iv) transferring any other task request to a position in the task request queue with a priority that is less than the first priority.

A method for improving the performance of an e-mail application program operating in a data processing system with a host processor and a disk array storage device that includes a plurality of logical storage devices and that operates in response to tasks including reconnect tasks requested when a logical storage device completes a task, a second category of tasks requested in response to certain activities within the disk array storage device and a third category of other tasks and wherein each e-mail transaction requires the completion of a log entry in a dedicated logical storage device as a condition precedent to the processing of any transaction, said method comprising the steps of:

• A) maintaining a task request queue for different task requests that schedule the order by which tasks are completed within the disk array storage device,
• B) upon receiving a task request related to any of the logical storage devices:
• i) determining the task category and the logical storage device related to the task,
• ii) transferring a reconnect task related to a logical storage device other than the dedicated logical storage device to a position in the task request queue of a first priority,
• iii) transferring a reconnect task request related to the dedicated logical storage device to that position in the task request queue having the highest priority,
• iv) transferring a task request of the second category related to the dedicated logical storage device to a position in the task request queue with a second priority that is less than the first priority, and
• v) transferring any other task request from the logical storage devices to a position in the task request queue with a priority that is less than the first priority and second priorities.

A method for improving the performance of an e-mail application program operating in a data processing system with a host processor and a disk array storage device that comprises a plurality of logical storage devices and that operates in response to tasks including reconnect tasks generated when a logical storage device completes a task, a second category of tasks generated in response to certain activities within the disk array storage device and a third category of other tasks and wherein each e-mail transaction requires a log entry in a dedicated logical storage device as a condition precedent to the processing of any transaction, said method comprising the steps of:

• A) maintaining a first-in, first-out task request queue for different tasks that schedule the order by which tasks are completed within the disk array storage device,
• B) normally adding reconnect tasks to the beginning of the the task request queue and other tasks to the end of the task request queue except for:
• i) transferring reconnect tasks related to the dedicated logical storage device to the head of the task request queue whereby reconnect tasks related to other logical storage devices are transferred to a location following any reconnect task related to the dedicated logical storage device, and
• ii) transferring a task request of the second category related to the dedicated logical storage device to a position in the task request queue that follows any reconnect task requests in the task request queue.