3Ware 9550SX-4LP User Guide - Page 162

Chapter 8. Configuring Units These changes can be made using 3DM2 or the CLI. Instructions for using migrate in 3DM2 are described below. For information about CLI, see 3ware 9000 Series Serial ATA RAID Controller CLI Guide. This section includes the following topics about changing existing configurations: • RAID Level Migration (RLM) Overview • Changing RAID Level • Expanding Unit Capacity • Informing the Operating System of Changed Configuration RAID Level Migration (RLM) Overview RAID level migration is the process of converting one RAID configuration to another. When you migrate a unit to a different configuration, the user data on it is redistributed to the format of the new configuration. This data redistribution process is a background task, similar to the rebuild or verify processes. Figure 64 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 data is moved from its original physical location. Figure 64. RAID Level Migration Example Typically, a unit is reconfigured with the same or more storage capacity. Sometimes additional drives are added. The following table shows valid reconfigurations, some of which will require the addition of more drives. 152 3ware Serial ATA RAID Controller User Guide