3Ware 9550SX-4LP User Guide - Page 193

About Background Tasks A unit being migrated can still be used (I/O still continues), however the performance will be affected while the migrating task is active. You can control how much affect this has on performance by setting the background task rate. For more information, see "Setting Background Task Rate" on page 183. Moving a Unit to Another Controller During Migration Moving a unit to another controller while the unit is in the migration state is supported with one restriction. If the unit was in the middle of the migration process and the controller was shutdown uncleanly, the unit cannot be moved to another controller until the unit has recovered from the unclean shutdown. For more information about migration, see "Changing An Existing Configuration" on page 151. About Self-tests Two self-tests can be set, to check whether UDMA Mode can be upgraded, and whether SMART thresholds have been exceeded. Initially, these tests are set to run every 24 hours. You can change the schedule for when they are run, and you can disable the tests, if you prefer not have to have them performed. For more information, see "Selecting Self-tests to be Performed" on page 188. Setting Background Task Rate In 3DM, you can set the relative performance of background tasks (initializing, rebuilding, and verifying) in relation to normal I/O activity. 9000-series controllers show separate settings for Rebuild Rate and Verify Rate. (Initialization occurs at the Rebuild rate.) 7000- and 8000-series controllers show only one setting for Task Rate, which applies to both rebuild and verify rates. Rebuild and verify tasks can be started manually or scheduled. For details about manually starting these processes, see "Rebuilding Units" on page 189 and "Verifying Units" on page 194. For details about scheduling rebuild, verify, and other tasks, see "Scheduling Background Tasks" on page 184. www.3ware.com 183