About Migration

Migration allows on-line units to be reconfigured. You can make these types of configuration changes:

RAID level
Unit capacity expansion
Change to stripe size

RAID level migration and unit capacity expansion tasks can be done together or separately.

Migration tasks follow the same schedule as rebuild and initialization tasks.

Because of the controller and disk resources required during migration, when migration is active, it has priority over other background tasks. When migration starts, it will take the highest priority over rebuild, initialize and verify.

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.

Migrate tasks are always done in the background, and can be initiated through either 3DM or the CLI. (Foreground migrations through 3BM are not supported.)

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.

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.

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