AMCC 720-0138-00 manual Appendix A. Glossary

Appendix A. Glossary

•Controller ID number. Unique number assigned to every 3ware controller in a system, starting with zero.

•Create an array. The process of selecting individual disk drives and selecting a RAID level. The array will appear to the operating system as a single unit. Overwrites any existing unit configuration data on the drives. Note that in 3ware software tools, arrays are referred to as units.

•DCB. Disk configuration block. This is 3ware proprietary RAID table information that is written to disk drives that are in a RAID unit, single disk, or spare. The DCB includes information on the unit type, unit members, RAID level, and other important RAID information.

•Delete an array. Deleting an array (or unit) is the process of returning the drives in a unit to individual drives. This erases the DCB information from the drives and deletes any data that was on them. When a unit is deleted from a controller, it is sometimes referred to as being “destroyed.” If you want to remove a unit without deleting the data on it, do not delete it; instead use the Remove feature in 3DM, and then physically remove the drives.

•Destroying. Same as deleting a unit.

•Degraded unit. A redundant unit that contains a drive that has failed.

•Disk roaming. When moving a unit from one controller to another, refers to putting disks back in a different order than they initially occupied, without harm to the data.

•Distributed parity. Parity (error correction code) data is distributed across several drives in RAID 5 configurations. Distributing parity data across drives provides both protection of data and good performance.

•Drive ID. A unique identifier for a specific drive in a system. Also called a port ID.

•Drive Number. The SCSI number, or channel number, of a particular drive.

•ECC. Error correction code. ECC Errors are grown defects that have occurred on a drive since it was last read.

•ECC Error policy. Determines whether an error detected during a rebuild stops the rebuild or whether the rebuild can continue in spite of the error. Specified by the Continue on Source Error During Rebuild unit policy.

•EMS (Enclosure Management Services). Chassis-monitoring functions for environmental, power, mechanical monitoring, and control using the I²C (chassis control) bus port.

•Export a unit. To remove the association of a unit with a controller. Does not affect the data on the drives. Used for array roaming, when you want to swap out a unit without powering down the system, and move the unit

136 3ware Serial ATA RAID Controller User Guide for the Power Mac G5