Administrator Guide

Table Of Contents
Glossary of terms
The following table lists definitions of the terms used in ME4 Series publications:
Table 43. Glossary of ME4 Series terms
Term Definition
2U12 An enclosure that is two rack units in height and can contain 12 disks.
2U24 An enclosure that is two rack units in height and can contain 24 disks.
5U84 An enclosure that is five rack units in height and can contain 84 disks.
AES Advanced Encryption Standard.
AFA All-flash array. A storage system that uses only SSDs, without tiering.
all-flash array See also AFA.
allocated page A page of virtual pool space that has been allocated to a volume to store data.
allocation rate The rate, in pages per minute, at which a virtual pool is allocating pages to its volumes because
they need more space to store data.
ALUA Asymmetric Logical Unit Access.
array See storage system.
ASC/ASCQ Additional Sense Code/Additional Sense Code Qualifier. Information on sense data returned by
a SCSI device.
automated tiered storage A virtual-storage feature that automatically uses the appropriate tier of disks to store data
based on how frequently the data is accessed. This enables higher-cost, higher-speed disks
to be used only for frequently needed data, while infrequently needed data can reside in
lower-cost, lower-speed disks.
auto-write-through See AWT
available disk A disk that is not a member of a disk group, is not configured as a spare, and is not in the
leftover state. It is available to be configured as a part of a disk group or as a spare. See also
compatible disk, dedicated spare, dynamic spare, global spare.
AWT Auto-write-through. A setting that specifies when the RAID controller cache mode
automatically changes from write-back to write-through
base volume A virtual volume that is not a snapshot of any other volume, and is the root of a snapshot tree.
canister See IOM.
CAPI Configuration Application Programming Interface. A proprietary protocol used for
communication between the Storage Controller and the Management Controller in a controller
module. CAPI is always enabled.
CHAP Challenge-Handshake Authentication Protocol.
chassis The sheet metal housing of an enclosure.
child volume The snapshot of a parent volume in a snapshot tree. See parent volume.
chunk size The amount of contiguous data that is written to a disk group member before moving to the
next member of the disk group.
CIM Common Information
Model
The data model for WBEM. It provides a common definition of management information for
systems, networks, applications and services, and allows for vendor extensions.
E
182 Glossary of terms