Table of Contents
Advertisement
F
Failed Physical Disk
A physical disk that has ceased to function, that
consistently functions improperly, or that is
inaccessible.
Fault Tolerance
Fault tolerance is the capability of the disk subsystem
to undergo a single drive failure per disk group
without compromising data integrity and processing
capability. The PERC 5 controllers provide this
support through redundant virtual disks in
RAID levels 1, 5, 10 and 50.
Fault tolerance is often associated with system
availability because it allows the system to be
available during drive failures. In case a disk fails, the
PERC 5 controllers support hot spare disks and the
auto-rebuild feature.
Firmware
Software stored in read-only memory (ROM) or
Programmable ROM (PROM). Firmware is often
responsible for the behavior of a system when it is first
turned on. A typical example would be a monitor
program in a system that loads the full operating
system from disk or from a network and then passes
control to the operating system.
Foreign Configuration
A RAID configuration that already exists on a
replacement physical disk that you install in a system.
You can import the existing configuration to the
RAID controller or clear it so you can create a
new one.
102
Glossary
Format
The process of writing a specific value to all data
fields on a physical disk, to map out unreadable or bad
sectors. Because most physical disks are formatted
when manufactured, formatting is usually done only
if a physical disk generates many media errors.
G
GB
Acronym for gigabyte(s). A gigabyte equals 1,024
megabytes or 1,073,741,824 bytes (2^30 bytes).
H
Host System
Any system on which the RAID controller is installed.
Mainframes, workstations, and personal systems can
all be considered host systems.
Hot Spare
An idle, powered on, stand-by physical disk ready for
immediate use in case of disk failure. It does not
contain any user data. A hot spare can be dedicated to
a single redundant virtual disk or it can be part of the
global hot-spare pool for all virtual disks controlled by
the controller.
When a disk fails, the controllers' firmware
automatically replaces and rebuilds the data from the
failed physical disk to the hot spare. Data can be
rebuilt only from virtual disks with redundancy (RAID
levels 1, 5, 10, or 50; not RAID 0), and the hot spare
must have sufficient capacity.
Hot Swap
Replacement of a failed component while the system
is running and operating normally.
Advertisement
Table of Contents
