IBM Elastic Storage System 3200 Service Guide

declustered array (DA)
A disjoint subset of the pdisks in a recovery group.
dependent leset
A leset that shares the inode space of an existing independent leset.
DFM
See direct FSP management (DFM).
DHCP
See Dynamic Host Conguration Protocol (DHCP).
drawer control module (DCM)
Essentially, a SAS expander on a storage enclosure drawer.
Dynamic Host Conguration Protocol (DHCP)
A standardized network protocol that is used on IP networks to dynamically distribute such network
conguration parameters as IP addresses for interfaces and services.
E
Elastic Storage System (ESS)
A high-performance, GPFS NSD solution made up of one or more building blocks. The ESS software
runs on ESS nodes - management server nodes and I/O server nodes.
encryption key
A mathematical value that allows components to verify that they are in communication with the
expected server. Encryption keys are based on a public or private key pair that is created during the
installation process. See also le encryption key (FEK), master encryption key (MEK).
ESS
See Elastic Storage System (ESS).
environmental service module (ESM)
Essentially, a SAS expander that attaches to the storage enclosure drives. In the case of multiple
drawers in a storage enclosure, the ESM attaches to drawer control modules.
ESM
See environmental service module (ESM).
F
failback
Cluster recovery from failover following repair. See also failover.
failover
(1) The assumption of le system duties by another node when a node fails. (2) The process of
transferring all control of the ESS to a single cluster in the ESS when the other clusters in the ESS fails.
See also cluster. (3) The routing of all transactions to a second controller when the rst controller fails.
See also cluster.
failure group
A collection of disks that share common access paths or adapter connection, and could all become
unavailable through a single hardware failure.
FEK
See le encryption key (FEK).
le encryption key (FEK)
A key used to encrypt sectors of an individual le. See also encryption key.
le system
The methods and data structures used to control how data is stored and retrieved.
le system descriptor
A data structure containing key information about a le system. This information includes the disks
assigned to the le system (stripe group), the current state of the le system, and pointers to key les
such as quota les and log les.
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IBM Elastic Storage System 3200: Service Guide

IBM Elastic Storage System 3200 Specifications

General

Brand	IBM
Model	Elastic Storage System 3200
Category	Storage
Language	English