Glossary

This glossary provides terms and definitions for the IBM Storage Scale System 3200 solution.

For other terms and definitions, see the IBM® Terminology website (opens in new window).

B

building block

A pair of servers with shared disk enclosures attached.

BOOTP

See Bootstrap Protocol (BOOTP).

Bootstrap Protocol (BOOTP)

A computer networking protocol that is used in IP networks to automatically assign an IP address to network devices from a configuration server.

C

CEC

See central processor complex (CPC).

central electronic complex (CEC)

See central processor complex (CPC).

central processor complex (CPC)

A physical collection of hardware that consists of channels, timers, main storage, and one or more central processors.

cluster

A loosely-coupled collection of independent systems, or nodes, organized into a network for the purpose of sharing resources and communicating with each other. See also GPFS cluster.

cluster manager

The node that monitors node status using disk leases, detects failures, drives recovery, and selects file system managers. The cluster manager is the node with the lowest node number among the quorum nodes that are operating at a particular time.

compute node

A node with a mounted GPFS file system that is used specifically to run a customer job. IBM Storage Scale System 3200 disks are not directly visible from and are not managed by this type of node.

CPC

See central processor complex (CPC).

D

DA

See declustered array (DA).

datagram

A basic transfer unit associated with a packet-switched network.

DCM

See drawer control module (DCM).

declustered array (DA)

A disjoint subset of the pdisks in a recovery group.

dependent fileset

A fileset that shares the inode space of an existing independent fileset.

DFM

See direct FSP management (DFM).

DHCP

See Dynamic Host Configuration Protocol (DHCP).

direct FSP management (DFM)

The ability of the xCAT software to communicate directly with the Power Systems server's service processor without the use of the HMC for management.

drawer control module (DCM)

Essentially, a SAS expander on a storage enclosure drawer.

Dynamic Host Configuration Protocol (DHCP)

A standardized network protocol that is used on IP networks to dynamically distribute such network configuration parameters as IP addresses for interfaces and services.

E

Elastic Storage Server (IBM Storage Scale System 3200)

A high-performance, GPFS NSD solution made up of one or more building blocks that runs on IBM Power Systems servers. The IBM Storage Scale System 3200 software runs on IBM Storage Scale System 3200 nodes - management server nodes and I/O server nodes.

IBM Storage Scale System 3200 Management Server (EMS)

An xCAT server is required to discover the I/O server nodes (working with the HMC), provision the operating system (OS) on the I/O server nodes, and deploy the ESS software on the management node and I/O server nodes. One management server is required for each IBM Storage Scale System 3200 system composed of one or more building blocks.

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 file encryption key (FEK), master encryption key (MEK).

IBM Storage Scale System 3200

See Elastic Storage Server (IBM Storage Scale System 3200).

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).

Extreme Cluster/Cloud Administration Toolkit (xCAT)

Scalable, open-source cluster management software. The management infrastructure of ESS is deployed by xCAT.

F

failback

Cluster recovery from failover following repair. See also failover.

failover

(1) The assumption of file 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 first 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 file encryption key (FEK).

file encryption key (FEK)

A key used to encrypt sectors of an individual file. See also encryption key.

file system

The methods and data structures used to control how data is stored and retrieved.

file system descriptor

A data structure containing key information about a file system. This information includes the disks assigned to the file system (stripe group), the current state of the file system, and pointers to key files such as quota files and log files.

file system descriptor quorum

The number of disks needed in order to write the file system descriptor correctly.

file system manager

The provider of services for all the nodes using a single file system. A file system manager processes changes to the state or description of the file system, controls the regions of disks that are allocated to each node, and controls token management and quota management.

fileset

A hierarchical grouping of files managed as a unit for balancing workload across a cluster. See also dependent fileset, independent fileset.

fileset snapshot

A snapshot of an independent fileset plus all dependent filesets.

flexible service processor (FSP)

Firmware that provices diagnosis, initialization, configuration, runtime error detection, and correction. Connects to the HMC.

FQDN

See fully-qualified domain name (FQDN).

FSP

See flexible service processor (FSP).

fully-qualified domain name (FQDN)

The complete domain name for a specific computer, or host, on the Internet. The FQDN consists of two parts: the hostname and the domain name.

G

GPFS cluster

A cluster of nodes defined as being available for use by GPFS file systems.

GPFS portability layer

The interface module that each installation must build for its specific hardware platform and Linux® distribution.

GPFS Storage Server (GSS)

A high-performance, GPFS NSD solution made up of one or more building blocks that runs on System x servers.

GSS

See GPFS Storage Server (GSS).

H

Hardware Management Console (HMC)

Standard interface for configuring and operating partitioned (LPAR) and SMP systems.

HMC

See Hardware Management Console (HMC).

I

IBM Security Key Lifecycle Manager (ISKLM)

For GPFS encryption, the ISKLM is used as an RKM server to store MEKs.

independent fileset

A fileset that has its own inode space.

indirect block

A block that contains pointers to other blocks.

inode

The internal structure that describes the individual files in the file system. There is one inode for each file.

inode space

A collection of inode number ranges reserved for an independent fileset, which enables more efficient per-fileset functions.

Internet Protocol (IP)

The primary communication protocol for relaying datagrams across network boundaries. Its routing function enables internetworking and essentially establishes the Internet.

I/O server node

An ESS node that is attached to the IBM Storage Scale System 3200 storage enclosures. It is the NSD server for the GPFS cluster.

IP

See Internet Protocol (IP).

IP over InfiniBand (IPoIB)

Provides an IP network emulation layer on top of InfiniBand RDMA networks, which allows existing applications to run over InfiniBand networks unmodified.

IPoIB

See IP over InfiniBand (IPoIB).

ISKLM

See IBM Security Key Lifecycle Manager (ISKLM).

J

JBOD array

The total collection of disks and enclosures over which a recovery group pair is defined.

K

kernel

The part of an operating system that contains programs for such tasks as input/output, management and control of hardware, and the scheduling of user tasks.

L

LACP

See Link Aggregation Control Protocol (LACP).

Link Aggregation Control Protocol (LACP)

Provides a way to control the bundling of several physical ports together to form a single logical channel.

logical partition (LPAR)

A subset of a server's hardware resources virtualized as a separate computer, each with its own operating system. See also node.

LPAR

See logical partition (LPAR).

M

management network

A network that is primarily responsible for booting and installing the designated server and compute nodes from the management server.

management server (MS)

An IBM Storage Scale System 3200 node that hosts the IBM Storage Scale System 3200 GUI and xCAT and is not connected to storage. It must be part of a GPFS cluster. From a system management perspective, it is the central coordinator of the cluster. It also serves as a client node in an IBM Storage Scale System 3200 building block.

master encryption key (MEK)

A key that is used to encrypt other keys. See also encryption key.

maximum transmission unit (MTU)

The largest packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network, such as the Internet. The TCP uses the MTU to determine the maximum size of each packet in any transmission.

MEK

See master encryption key (MEK).

metadata

A data structure that contains access information about file data. Such structures include inodes, indirect blocks, and directories. These data structures are not accessible to user applications.

MS

See management server (MS).

MTU

See maximum transmission unit (MTU).

N

Network File System (NFS)

A protocol (developed by Sun Microsystems, Incorporated) that allows any host in a network to gain access to another host or netgroup and their file directories.

Network Shared Disk (NSD)

A component for cluster-wide disk naming and access.

NSD volume ID

A unique 16-digit hexadecimal number that is used to identify and access all NSDs.

node

An individual operating-system image within a cluster. Depending on the way in which the computer system is partitioned, it can contain one or more nodes. In a Power Systems environment, synonymous with logical partition.

node descriptor

A definition that indicates how IBM Storage Scale uses a node. Possible functions include: manager node, client node, quorum node, and non-quorum node.

node number

A number that is generated and maintained by IBM Storage Scale as the cluster is created, and as nodes are added to or deleted from the cluster.

node quorum

The minimum number of nodes that must be running in order for the daemon to start.

node quorum with tiebreaker disks

A form of quorum that allows IBM Storage Scale to run with as little as one quorum node available, as long as there is access to a majority of the quorum disks.

non-quorum node

A node in a cluster that is not counted for the purposes of quorum determination.

O

OFED

See OpenFabrics Enterprise Distribution (OFED).

OpenFabrics Enterprise Distribution (OFED)

An open-source software stack includes software drivers, core kernel code, middleware, and user-level interfaces.

P

pdisk

A physical disk.

PortFast

A Cisco network function that can be configured to resolve any problems that could be caused by the amount of time STP takes to transition ports to the Forwarding state.

R

RAID

See redundant array of independent disks (RAID).

RDMA

See remote direct memory access (RDMA).

redundant array of independent disks (RAID)

A collection of two or more disk physical drives that present to the host an image of one or more logical disk drives. In the event of a single physical device failure, the data can be read or regenerated from the other disk drives in the array due to data redundancy.

recovery

The process of restoring access to file system data when a failure has occurred. Recovery can involve reconstructing data or providing alternative routing through a different server.

recovery group (RG)

A collection of disks that is set up by IBM Storage Scale RAID, in which each disk is connected physically to two servers: a primary server and a backup server.

remote direct memory access (RDMA)

A direct memory access from the memory of one computer into that of another without involving either one's operating system. This permits high-throughput, low-latency networking, which is especially useful in massively-parallel computer clusters.

RGD

See recovery group data (RGD).

remote key management server (RKM server)

A server that is used to store master encryption keys.

RG

See recovery group (RG).

recovery group data (RGD)

Data that is associated with a recovery group.

RKM server

See remote key management server (RKM server).

S

SAS

See Serial Attached SCSI (SAS).

secure shell (SSH)

A cryptographic (encrypted) network protocol for initiating text-based shell sessions securely on remote computers.

Serial Attached SCSI (SAS)

A point-to-point serial protocol that moves data to and from such computer storage devices as hard drives and tape drives.

service network

A private network that is dedicated to managing POWER8 servers. Provides Ethernet-based connectivity among the FSP, CPC, HMC, and management server.

SMP

See symmetric multiprocessing (SMP).

Spanning Tree Protocol (STP)

A network protocol that ensures a loop-free topology for any bridged Ethernet local-area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them.

SSH

See secure shell (SSH).

STP

See Spanning Tree Protocol (STP).

symmetric multiprocessing (SMP)

A computer architecture that provides fast performance by making multiple processors available to complete individual processes simultaneously.

T

TCP

See Transmission Control Protocol (TCP).

Transmission Control Protocol (TCP)

A core protocol of the Internet Protocol Suite that provides reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating over an IP network.

V

VCD

See vdisk configuration data (VCD).

vdisk

A virtual disk.

vdisk configuration data (VCD)

Configuration data that is associated with a virtual disk.

X

xCAT

See Extreme Cluster/Cloud Administration Toolkit.