Administrator Guide

detach rule
Predefined rules that determine which cluster continues I/O when connectivity between clusters is lost. A cluster loses
connectivity to its peer cluster due to cluster partition or cluster failure.
Detach rules are applied at two levels; to individual volumes, and to consistency groups. If a volume is a member of a
consistency group, the group detach rule overrides the rule set for the individual volumes. Note that all detach rules may
be overridden by metro node Witness, if metro node Witness is deployed.
device
A combination of one or more extents to which you add specific RAID properties. Local devices use storage from only one
cluster. In metro node Metro and Geo configurations, distributed devices use storage from both clusters.
director
A CPU module that runs metro node OS, the core metro node software. There are two directors (A and B) in each engine, and
each has dedicated resources and is capable of functioning independently.
dirty data
The write-specific data stored in the cache memory that is yet to be written to disk.
disaster recovery (DR)
The ability to restart system operations after an error, preventing data loss.
discovered array
An array that is connected to the SAN and discovered by metro node.
disk cache
A section of RAM that provides cache between the disk and the CPU. RAMs access time is significantly faster than disk access
time. Therefore, a disk-caching program enables the computer to operate faster by placing recently accessed data in the disk
cache.
Distributed consistency groups
The RecoverPoint consistency group is divided into four segments. Each segment runs on one primary RPA and one to three
secondary RPAs.
Distributed consistency groups enable a much higher throughput and IOPS rate, regardless of the amount of data being
replicated.
distributed device
A RAID 1 device whose mirrors are in different metro node clusters.
distributed file system (DFS)
Supports the sharing of files and resources in the form of persistent storage over a network.
distributed RAID1 device (DR1)
Distributed devices have physical volumes at both clusters in a metro node Metro configuration for simultaneous active/active
and read/write access using AccessAnywhere.
E
Ethernet
A Local Area Network (LAN) protocol. Ethernet uses a bus topology, meaning all devices are connected to a central cable, and
supports data transfer rates of between 10 megabits per second and 10 gigabits per second. For example, 100 Base-T supports
data transfer rates of 100 Mb/s.
event
A log message that results from a significant action initiated by a user or the system.
extent
All or a portion (range of blocks) of a storage volume.
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Glossary