AMCC 3WARE 720-0138-00 - Manual (Page 145)

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to another controller. Compare to Delete, which erases all unit
configuration information from the drive.
• Exportable unit or drive . 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.
• Hot swapping . The process of removing a disk drive from the system
while the power is on. Hot swapping can be used to remove units with
data on them, when they are installed in hot-swap carriers. This is referred
to as array roaming. Hot swapping can also be used to remove and
replaced failed drives when a hot-swap carrier is used.
• I²C-(or Inter-IC) bus . A two-wire serial bus solution used as a control,
diagnostic, environmental, and power management for EMS (enclosure
management services).
• Import a unit . Attach a set of disk drives with an existing configuration to
a controller and make the controller aware of the unit. Does not affect the
data on the drives.
• Initialize. For 3ware SATA RAID controllers, initialize means to put the
redundant data on the drives of redundant units into a known state so that
data can be recovered in the event of a disk drive failure. For RAID 1 and
10, initialization copies the data from the lower port to the higher port.
For RAID 5, initialization calculates the RAID 5 parity and writes it to
disk (background initialization). This is sometimes referred to as
resynching, and does not erase user data.
• Logical Units. This term is used in the 3ware CLI. It is usually shortened
to “units.” These are block devices presented to the operating system. A
logical unit can be a one-tier, two-tier, or three-tier arrangement. Spare,
and Single logical units are examples of one-tier units. RAID 1 and RAID
5 are examples of two-tier units and as such will have sub-units. RAID 10
is an example of a three-tier unit and as such will have sub-sub-units.
• Migration. The process of changing the characteristics of a unit. The
change can be to expand the capacity of the unit (OCE), change the stripe