Appendix A. Glossary
234
3ware 9550SX Serial ATA RAID Controller User Guide
Migration.
The process of changing the characteristics of a unit. The
change can be to expand the capacity of the array (OCE), change the
stripe size of the array, change the array from redundant to non-redundant,
or to change the array from non-redundant to redundant
.
Mirrored disk array.
A pair of drives on which the same data is written,
so that each provides a backup for the other. If one drive fails, the data is
preserved on the paired drive. Mirrored disk arrays include RAID 1 and
RAID 10.
NCQ (Native Command Queuing).
A feature designed to improve
performance of SATA hard disks in some applications that require a lot of
random access of data, such as server-type applications. When NCQ is
enabled, the commands are reordered on the drive itself.
NCQ must be supported by the drive and is only available on the 9550SX
controller. NCQ must be turned on in both the drive and the RAID
controller. By default, the RAID unit’s queue policy is enabled when
creating a unit.
Non-redundant units.
A disk array without fault tolerance (RAID 0,
single disk, or JBOD.).
OCE (Online Capacity Expansion).
The process of increasing the size of
an existing RAID unit without having to create a new array. 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 ID
. A unique identifier for a specific port in a system. Also called a
drive ID.
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 degraded 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.
Summary of Contents for 9550SXU-16ML - Sata Rohs
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Page 124: ...Chapter 6 3ware Disk Manager 3DM 2 114 3ware 9550SX Serial ATA RAID Controller User Guide...
Page 220: ...Chapter 10 Maintaining Your Controller 210 3ware 9550SX Serial ATA RAID Controller User Guide...
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