A logical disk created from available space and made
up of one or more segments on one or more physical disks. Arrays are typically
used to provide data redundancy or enhanced I/O performance. See also
container, segment,
volume, spanned
volume, RAID 0, RAID 1,
RAID 5, and RAID 10.
Also known as a container.
Array Configuration Utility
An application used to create, configure, and manage
arrays from the controller's BIOS.
AT Bus Attachment. Standard parallel interface to
IDE hard disks typically used in desktop computers and some entry-level
servers. SATA (Serial ATA), is a successor
to parallel ATA, which is sometimes referred to as PATA.
available space/segment
Unused space on an initialized disk from which logical
devices (arrays) are created. When an array is deleted, the space that
it used is returned to the available space pool.
Background initialization of a redundant array. The
array is accessible throughout. RAID 1 copies the contents of the
primary drive to a secondary drive. See also clear.
Fast-access memory on the controller that serves
as intermediate storage for data that is read from, or written to, drives.
capacity
Total usable space available in megabytes or gigabytes.
CERCCCU
CERC Container Configuration Utility. An application
used to create, configure, and manage arrays from the controller's MS-DOS.
channel
Any path, or bus, used for the transfer of
data and the control of information between storage devices and a RAID
controller. For SATA channels, each channel has a single drive capacity.
Foreground initialization of a fault-tolerant array.
A clear operation zeros all blocks of the array. The array is not accessible
until the clear task is complete.
concatenation
Joining of physical or logical drives in sequential
order.
consistency check command
The controller continuously performs a verification
on a redundant array to data integrity. In the case of RAID 1 or
10, consistency checks assure that the data between like blocks match.
In the case of a RAID 5, consistency checks assure that data in the
stripe and the calculated parity for the stripe match.
A redundant (for example, a RAID 1) array in
which one or more members have failed. The data is intact but redundancy
has been compromised. Any further failure would cause the array to fail
and result in data loss.
dirty data
Data that has been written to a cache
but which has not been "flushed" out to its final destination.
Unique disk identifier that consists of the channel
number, ID, and LUN (channel:ID:LUN), for example, 1:04:0. See also channel.
drive LED
Disk indicator LED that illuminates during read or
write operations.
E
event
Notification or alert from the system, indicating
that a change has occurred.
event log
File used to maintain information about prior controller
activities or errors.
event notification
Process for transmitting events.
F
failed
State of a nonredundant
array that has suffered a single drive failure, or a redundant array that
has suffered multiple drive failures. A failed array is inaccessible and
data is lost.
failed segment
A segment that
is no longer usable by an array because it is either logically bad and
therefore no longer needed, or physically damaged.
Refers to an array that can continue to function
after a disk drive failure without loss of data. See also redundant.
foreign disk
Disk that has previously been initialized on another
type of RAID controller. The RAID signature on the disk allows the RAID
controller to identify whether or not the disk was initialized on the
controller it is currently connected to.
Basic unit of nonvolatile, nonremovable, magnetic
storage media. See also disk drive.
hot spare
A hard drive, an array member, that is not used in
day-to-day data storage but, instead, is reserved for use as a replacement
for one of the other drives in the array in the event of a failure.
hot swap
To remove a component from a system and install a
new component while the power is on and the system is running.
I
impacted
An impacted array is one which has been created but
for some reason the initial build operation did not complete. All member
drives are present and operational, and all data written to the array
is protected. To optimize the array, run a Verify with Fix Task.
initialize
Process of preparing a disk for use by the controller.
When a disk is initialized, the controller records the RAID signature
on the disk.
initialized array
An array that is ready for data reads and writes.
Arrays can be initialized by build or
clear.
L
legacy disk
Disk that contained a valid partition
table when connected to the controller. The controller manages the disk
as a legacy disk array where there is a one-to-one logical-to-physical
mapping of array to disk.
logical device
Volume comprised of space from one or more physical
drives and presented to the operating system as if it were a single storage
unit.
low-level format
Process performed by the drive firmware that completely
removes the file system from the disk.
Object that represents a component that cannot be
configured by the controller management software; for example, a missing
drive.
Q
quick init
An array initialized using the Quick Init option
is available immediately, with no on-going background controller activity.
All data written to an array that has been quick initialized is protected.
R
RAID
Redundant Array of Independent Disks (alternative
definition Redundant Array of Inexpensive Disks).
RAID 0
A single-level array
consisting of two or more equal-sized segments residing on different disks.
RAID 0 distributes data evenly across its respective drives in equal-sized
sections called stripes. RAID 0
arrays are not redundant.
RAID 1
Single-level array consisting of two equal segments
residing on two different drives. Provides redundancy by storing identical
copies on two drives.
Single-level array consisting of at least three drives.
Like RAID 0, data is striped across the drives. However, in RAID 5,
parity is stored separately from data, and occupies the equivalent of
one drive. The controller generates parity every time data is written
to the array, and it is distributed in stripes across all the drives.
RAID 10
Dual-level RAID type created by using two or more
equal-sized RAID 1 arrays to create a RAID 0. Both read and
write performance are improved due to array striping. However, the performance
improvement costs additional storage space due to the mirroring of the
arrays.
RAID signature
The area on each disk reserved for use by the RAID
controller.
RAID volume
Concatenates two or more arrays of the same type.
rebuild
Background regeneration of redundant data on a RAID 1.
reconfiguration
Process of expanding an array or migrating an array
from one RAID type to another; changing the stripe
size of a RAID 0, or moving a logical device's segments
to other disks.
redundant
The ability of an array to maintain operability when
one or more hardware failures occur. RAID 1 is redundant. In the
event of a drive failure, redundant arrays can be restored to normal operation
by replacing the failed drive and rebuilding the array.
rescan
Process of updating the current screen to show all
currently available resources.
S
segment
Contiguous area of a physical drive that makes up
some or all of an array. When the software creates an array, it automatically
converts space into segments.
SATA (Serial ATA)
A successor to ATA that uses a serial, instead of
parallel, interface.
simple volume
A volume made up of disk space from a single disk.
It can consist of a single region on a disk or concatenated, multiple
regions of the same disk.
Contiguous set of data distributed across all the
disks in an array. A striped array distributes data evenly across all
members in equal-sized sections called stripes.
stripe size
The amount of data in each section of a striped array.
An operation that occurs only on the RAID controller,
asynchronous to all other operations; for example, initializing a disk
or verifying an array. Some tasks can take an extended period of time,
particularly if the RAID controller is also performing intensive data
I/O while the task is running.
