AMCC 3WARE 720-0138-00 - Manual (Page 144)

Appendix A. Glossary
136 3ware Serial ATA RAID Controller User Guide for the Power Mac G5
• 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