Automated job scheduling in a data storage and/or retrieval system

An automated method of scheduling data storage or retrieval jobs in a data storage and/or retrieval system in which stored data is distributed between multiple data storage volumes, said method comprising:

• (i) maintaining a queue of data storage or retrieval jobs for execution;
• and
• (ii) adding a newly initiated job to said queue so that:
• (a) if said newly initiated job requires access to the same data storage volume as a further job already in said queue, said newly initiated job is added to said queue at an adjacent queue position to that further job;
• and
• (b) if said newly initiated job does not require access to the same data storage volume as any other job already in said queue, adding said newly initiated job to said queue at a queue position independent of the data storage volumes of other jobs in said queue;
• wherein each queued job has an associated estimated duration and selectively has an associated required latest completion time that was assigned to the job prior to a user-initiated job request for the job, and said method further comprising:
• maintaining an estimated start time for the job at the head of said queue;
• predicting a completion time for each job in said queue on the basis of said estimated start time of said job at the head of said queue and the estimated durations of jobs in said queue;
• and
• if the predicted completion time for a job is after the required latest completion time for that job, moving that job to a higher position within said queue.

Job scheduling apparatus for scheduling data storage or retrieval jobs in a data storage and/or retrieval system in which stored data is distributed between multiple data storage volumes, said apparatus comprising:

• (i) means for maintaining a plurality of queues of data storage or retrieval jobs for execution each of said queues having a distinct execution priority type;
• and
• (ii) means for determining which one of said queues has an execution priority type that matches a user-assigned priority type for a newly initiated job, and adding said newly initiated job to said one queue so determined so that:
• (a) if said newly initiated job requires access to the same data storage volume as a further job already in said one queue, said newly initiated job is added to said one queue at an adjacent queue position to that further job;
• and
• (b) if said newly initiated job does not require access to the same data storage volume as any other job already in said one queue, said newly initiated job is added to said one queue at a queue position independent of the data storage volumes of other jobs in said one queue.