AMCC 3WARE 720-0138-00 - Manual (Page 60)

Chapter 5. Configuring Units
52 3ware Serial ATA RAID Controller User Guide for the Power Mac G5
Changing RAID Level
You can use migrate to change the RAID level of an existing unit while the
unit is online, without experiencing any data loss. When you change a RAID
level, you may also add one or more drives to the unit. You can also migrate to
change the unit's stripe size. For example, a four-drive RAID 5 with a 64KB
stripe size can be migrated to a four-drive RAID 5 with 256KB stripe size.
The steps below describe how to change a RAID level in 3DM2.
To change the RAID level of a unit
1 In 3DM 2, choose Management > Maintenance .
2 In the Unit Maintenance table on the Maintenance Page, select the unit for
which you wish to change the RAID level, by checking the box next to
the Unit ID.
3 Click the Migrate Unit button.
The Migrate dialog box appears.
4 Select any drives to be added to the unit.
5 Select the new RAID level.
6 Optionally, select a new Stripe size.
7 Click OK .
The Maintenance page updates to show the new unit and the Migration
progress.
8 Inform the operating system of the change, as described below under
“Informing the Operating System of Changed Configuration”.
Note: Once migration starts, the unit stays in the migrating state until the migration
process is complete. The migration process cannot be aborted, and must be
allowed to finish before a rebuild or verify to the unit is permitted.
Warning: It is important that you allow migration to complete before adding to the
unit. Making physical changes to the unit during migration may cause the migration
process to stop, and can jeopardize the safety of your data.
Note: You can only migrate a unit to a RAID level that has the same or more
capacity as the existing one. A four-drive RAID 5 unit can migrate to a four-drive
RAID 0, but a three-drive RAID 0 unit cannot migrate to a three-drive RAID 5,
without adding another drive, due to the need for additional storage capacity for
parity bits.