Appendix A. Glossary
248
3ware Serial ATA RAID Controller User Guide
•
OCE (Online Capacity Expansion).
The process of increasing the size of
an existing RAID unit without having to create a new unit. See also
migration
.
•
Parity.
Information that the controller calculates using an exclusive OR
(XOR) algorithm and writes to the disk drives in RAID 5 and RAID 50
units. This data can be used with the remaining user data to recover the
lost data if a disk drive fails.
•
PCB
. Printed circuit board.
•
P-Chip.
PCI interface chip that connects the PCI bus to the high-speed
internal bus and routes all data between the two using a packet switched
fabric. There is one P-chip per controller card.
•
Port.
A controller has one or many ports (typically 4, 8, 12, 16). Each port
can be attached to a single disk drive. On a controller with a multilane
serial port connector, one connector supports four ports.
•
Port ID
. A unique identifier for a specific port in a system. Also called a
drive ID.
•
RAID.
Redundant array of inexpensive disks, combined into a unit
(array), to increase your storage system’s performance and provide fault
tolerance (protection against data loss).
•
Rebuild task schedule
. The specification for when rebuilding, may
occur, including start time and duration.
•
Rebuild a unit
. To generate data on a new drive after it is put into service
to replace a failed drive in a fault tolerant unit (for example, RAID 1, 10,
5, or 50).
•
Redundancy.
Duplication of data on another drive or drives, so that it is
protected in the event of a drive failure.
•
Remove a drive.
The process of making a drive unavailable to the
controller.
•
Remove a unit.
The process of making a unit unavailable to the
controller and the operating system. After a unit is removed it can be hot
swapped out of the system. This is sometimes referred to as exporting a
unit.
•
RLM (RAID Level Migration).
The process of using an existing unit of
one or more drives and converting it to a new RAID type without having
to delete the original unit. For example, converting a single disk to a
mirrored disk or converting a RAID 0 unit to a RAID 5 unit.
•
Self-test.
A test that can be performed on a scheduled basis. Available
self-tests include Upgrade UDMA mode and Check SMART Thresholds.
•
Stagger time.
The delay between drive groups that will spin up, at one
time, on a particular controller.
