AMCC 720-0138-00 manual Scheduling Background Tasks, Background Task Prioritization

Chapter 6. Maintaining Units

Background Task Prioritization

Although migration tasks follow the same schedule as rebuild and initialization tasks, they are always given the highest priority because of the controller and disk resources required during migration.

Once a unit is put into the migration state, it must be allowed to complete the process. While migrating, rebuilds or verifies to the unit are not permitted.

Rebuilding preempts verify operations. If a unit requires rebuilding, that process will take place before the unit is verified.

Controllers can work on multiple units at the same time. This means that if you have both a redundant unit and a non-redundant unit, the verification of the redundant unit and the media scan of the non-redundant unit will occur at the same time.

Scheduling Background Tasks

You can set up scheduling windows for when background tasks occur so that routine maintenance of storage media occurs when it will be least likely to interfere with day-to-day work on the system (peak I/O times). By creating and using schedules, you can specify when active rebuilding, migrating, verifying, and testing of units should occur. For example, you might these tasks to occur at 2AM each day, or on weekends.

The initial schedule setting is to “Ignore Schedule.” This allows the controller firmware to automatically initiate background tasks.

Note: Initialization follows the rebuild/migrate schedule.

Rebuild/migrate, verify, and self-test tasks are scheduled separately, but in a very similar way. You can perform the following scheduling tasks:

•Viewing Current Task Schedules

•Turning On or Off Use of a Task Schedule

•Removing a Task Schedule

•Adding a New Task Schedule Slot

•Selecting Self-tests to be Performed

76 3ware Serial ATA RAID Controller User Guide for the Power Mac G5