Avago Technologies 3ware 9650SE-12ML (Channel) - Manual (Page 328)

Glossary
316 3ware SAS/SATA RAID Software User Guide, Version 9.5.1
• Distributed parity. Parity (error correction code) data is distributed
across several drives in RAID 5, RAID 6, and RAID 50 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
Ignore ECC (Continue on Source Error When
Rebuilding) unit policy.
• Enclosure. An enclosure houses drives and a backplane. The backplane
may have an expander.
• Expander. Expanders are simple switches in enclosures that provide
connectivity between the 3ware 9690SA RAID controller and the other
devices in the SAS domain. Expanders allow one phy to connect to
multiple drives. Expanders in enclosures attached to an external wideport
of the 9690SA RAID controller can be cascaded up to 4 times.
• 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
to another controller. Compare to Delete, which erases all unit
configuration information from the drive.
• Exportable unit or drive . In 3BM (BIOS), exportable units and drives
are those that will be available to the operating system when you boot
your computer.
• Fault tolerant . A RAID unit which provides the ability to recover from a
failed drive, either because the data is duplicated (as when drives are
mirrored) or because of error checking (as in a RAID 5 unit).
• Firmware. Computer programming instructions that are stored in a read-
only memory on the controller rather than being implemented through
software.
• Grown defect. Defects that arise on a disk from daily use.
• Hot spare. A drive that is available, online, and designated as a spare.
When a drive fails in a redundant unit, causing the unit to become
degraded, a hot spare can replace the failed drive automatically and the
unit will be rebuilt.