mirrored caching A process in which half of each controller’s write cache mirrors the companion
controller’s write cache. The total memory available for cached write data is
reduced by half, but the level of protection is greater.
mirroring The act of creating an exact copy or image of data.
MTBF Mean Time Failures. The average time from start of use to first failure in a large
population of identical systems, components, or devices.
multi-mode fiber A fiber optic cable with a diameter large enough (50 microns or more) to allow
multiple streams of light to travel different paths from the transmitter to the receiver.
This transmission mode enables bidirectional transmissions.
Network Storage
Controller
See NSC.
node port A device port that can operate on the arbitrated loop topology.
non-OFC (Open
Fibre Control)
A laser transceiver whose lower-intensity output does not require special open
Fibre Channel mechanisms for eye protection. The Enterprise storage system
transceivers are non-OFC compatible.
NSC Network Storage Controller. The HSV Controllers used by the Enterprise storage
system.
NVRAM Nonvolatile Random Access Memory. Memory whose contents are not lost when
a system is turned Off or if there is a power failure. This is achieved through the
use of UPS batteries or implementation technology such as flash memory. NVRAM
is commonly used to store important configuration parameters.
occupancy alarm
level
A percentage of the total disk group capacity in blocks. When the number of
blocks in the disk group that contain user data reaches this level, an event code
is generated. The alarm level is specified by the user.
online/nearonline An online drive is a normal, high-performance drive, while a near-online drive
is a lower-performance drive.
OpenView Storage
Management
Server
A centralized, appliance-based monitoring and management interface that
supports multiple applications, operating systems, hardware platforms, storage
systems, tape libraries and SAN-related interconnect devices. It is included and
resides on the SANWorks Management Server, a single aggregation point for
data management.
param That portion of the HSV controller termination code display that defines:
• The 2-character parameter identifier that is a decimal number in the 0 through
31 range.
• The 8-character parameter code that is a hexadecimal number.
See also IDX and TC.
password A security interlock where the purpose is to allow:
• A management agent to control only certain storage systems
• Only certain management agents to control a storage system
PDM Power Distribution Module. A thermal circuit breaker-equipped power strip that
distributes power from a PDU to Enterprise Storage System elements.
Glossary118
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