User guide

Chapter 9. Maintaining Units
156 3ware Serial ATA RAID Controller User Guide
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.
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
Note: Initialization follows the rebuild/migrate schedule.