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to the disk, and writes the data out to a new location on the
disk. Since the problem has been resolved, no error is
reported to the system.
Disk System
A storage system capable of supporting only disks.
Drive Groups
A group of individual disk drives (preferably identical) that
are logically tied to each other and are addressed as a single
unit. In some cases this may be called a drive "pack" when
referring to just the physical devices. All the physical
devices in a drive group should have the same size;
otherwise, each of the disks in the group will effectively
have the capacity of the smallest member. The total size of
the drive group will be the size of the smallest disk in the
group multiplied by the number of disks in the group. For
example, if you have 4 disks of 400MB each and 1 disk of
200MB in a pack, the effective capacity available for use is
only 1000MB (5x200), not 1800MB.
Dual Active
A pair of components, such as storage controllers in a
failure tolerant storage system, that share a task or set of
tasks when both are functioning normally. When one
component of the pair fails, the other takes the entire load.
Dual active controllers (also called Active-Active
controllers) are connected to the same set of devices and
provide a combination of higher I/O performance and
greater failure tolerance than a single controller.
E
Embedded Storage Controller
An intelligent storage controller that mounts in a host
computer's housing and attaches directly to a host's
memory bus with no intervening I/O adapter or I/O bus.
External RAID Controller
A RAID controller in its own enclosure, rather than
incorporated into a PC or server. External RAID
controllers are often referred to as a bridge RAID
controller. SANArray FL, FF, FFx, and Pro FF2 controllers
are external RAID controllers.
F
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Failover
A mode of operation for failure tolerant systems in which a
component has failed and a redundant component has
assumed its functions.
Failover Port
A fibre channel port capable of assuming I/O requests for
another, failed port on the loop. During normal operation, a
failover port may be active or inactive. Failover ports
assume the same loop ID and, optionally, the same node
from the failed port.
Failure
A detectable physical change in hardware, requiring
replacement of the component.
Fault Tolerance, Failure Tolerance
The ability of a system to continue to perform its function
even when one of its components has failed. A fault
tolerant system requires redundancy in disk drives, power
supplies, adapters, controllers, and cabling. RAID
controllers offer high levels of fault tolerance.
Fibre Channel
Technology for transmitting data between computer
devices at a data rate of up to 2 Gbps (two billion bits per
second), especially suited for connecting computer servers
to shared storage devices and for interconnecting storage
controllers and drives. Fibre Channel is expected to
replace the Small System Computer Interface (SCSI) as the
transmission interface between servers and clustered
storage devices. It is also more flexible: devices can be as
far as ten kilometers (about six miles) apart. The longer
distance requires optical fiber as the physical medium;
however, Fibre Channel also works using coaxial cable and
ordinary telephone twisted pair wires.
Foreground Initialization
During the initialization process all data is cleared and
zeros are written to the disks. With the size of system
drives growing dramatically, a foreground initialization
takes several hours to complete.
H
Hard Disk
Spheras Storage Director Installation & User Guide
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