Chapter 8. Configuring Units144 3ware 9550SX Serial ATA RAID Controller User GuideChanging An Existing ConfigurationWith 3ware 9000 series RAID controllers you can convert one RAIDconfiguration into another while the unit is online. This process is known asRAID Level Migration (RLM).Note: Units on a 7xxx/8xxx series controller cannot be migrated.You can use RAID Level Migration to make two main types of configurationchanges: RAID Level Unit Capacity ExpansionYou can also use RLM to change the stripe size of a unit.These changes can be made using 3DM2 or the CLI. Instructions for usingmigrate in 3DM2 are described below. For information about CLI, see 3ware9000 Series Serial ATA RAID Controller CLI Guide.This section includes the following topics about changing existingconfigurations: RAID Level Migration (RLM) Overview Changing RAID Level Expanding Unit Capacity Informing the Operating System of Changed ConfigurationRAID Level Migration (RLM) OverviewRAID level migration is the process of converting one RAID configuration toanother. When you migrate a unit to a different configuration, the user data onit is redistributed to the format of the new configuration. This dataredistribution process is a background task, similar to the rebuild or verifyprocesses.Figure 63 shows an example of how data is reconfigured during a migration.In this example, the migration is from a 4-drive RAID 0 to a 6-drive RAID 5,with both having the same stripe size. As can be seen, every piece of user datais moved from its original physical location.
