Glossary

Active Directory

A directory service that implements LDAP in a Windows environment. It provides a hierarchical structure for organizing access to data.

administration password

The password required to log into the Management screens of Appliance Manager

bonded network interface

Virtual network interface that consists of real interfaces working in tandem. A virtual interface can provide the aggregated bandwidth of all of the interfaces that you used to create it.

cell ID

A number associated with a node that is used by the CXFS software and appears in messages.

CHAP

Challenge Handshake Authentication Protocol is a means of authentication used between a client and server where the password is sent over the wire in a form that is impossible to discover and impossible to replay. Both client and server must know what the original password is, but someone snooping on wire traffic cannot recover the password and cannot later send the original (snooped upon) authentication packet to the server in an attempt to try to trick it into letting them authenticate as a valid client.

CIFS

Common internet filesystem. This protocol is usually used by Microsoft Windows clients.

client-only node

A node in a CXFS cluster that does not run cluster administration daemons and is not capable of coordinating CXFS metadata.

cluster

A cluster is the set of systems (nodes) configured to work together as a single computing resource. A cluster is identified by a simple name and a cluster ID. In CXFS, a cluster running multiple operating systems is known as a multiOS cluster.

current metric

Metric drawn live from the server or taken from the last few minutes of the metric archives.

CXFS

Clustered XFS filesystem.

DCM

Disk cache manager, which lets you configure the DMF disk MSP to manage data on secondary storage, allowing you to further migrate the data to tape as needed.

default network gateway

The IP address of the router that this system should use to communicate with machines that are outside of its subnet.

DHCP

Dynamic host configuration protocol (DHCP) allows one or more server systems to dynamically distribute network IP addresses and site configuration parameters to new or requesting client systems. By using DHCP, a site with only a few available addresses can serve a large number of hosts that connect to the network only occasionally, or a large site can manage the permanent assignment of addresses with a minimum of administrative attention. The NAS server can be configured as a DHCP client.

directory service

See name service.

disk IOPS

Disk I/O per second.

disk striping

Writing data in units to multiple disks in a round-robin fashion, increasing IOPS performance.

disk throughput

The amount of data that is transferred to and from disks.

distinguished name

A unique identifier for an entry in an LDAP directory tree structure.

DMF

Data Migration Facility, a hierarchical storage management system for SGI environments.

DNS

Domain name system

DRDB

Distributed Replicated Block Device. See http://www.drbd.org/.

dual-resident file

In DCM, a cache-resident copy of a migrated file that has already been copied to tape, and can therefore be released quickly in order to prevent the cache filling, without any need to first copy it to tape

FC

Fibre Channel storage interface connection.

fence

The isolation of a problem node so that it cannot access I/O devices, and therefore cannot corrupt data in the shared CXFS filesystem.

FQDN

Fully qualified domain name.

gigabyte

1024 megabytes (also known as gibibyte). On the DMF Configuration screens, disk sizes use multipliers that are powers of 1000, such as kB, MB and GB. This is for consistency with the DMF documentation and log files. However, the rest of Appliance Manager, including the DMF Monitoring screens, use multipliers that are powers of 1024, such as kiB, MiB and GiB.

historic metric

Metric taken exclusively from the metric archives.

hot spare

Disk drive within a RAID array that is not used unless another drive within the RAID array fails, at which point it is added to the filesystem to replace the failed drive without shutting the filesystem down or interrupting service.

idle time

Time that remained when the CPU could not find any tasks to run.

initiator

The client accessing the storage in an iSCSI network.

interrupt time

Time the CPU spent processing requests from I/O devices. In a storage server context, these are almost exclusively generated by disk operations or network packets and by switching between processes.

I/O fencing

See fence.

IOPS

I/O per second.

IPMI

Intelligent Platform Management Interface, a system reset method.

IPoIB

IP over InfiniBand.

iSCSI

Internet Small Computers Systems Interface is a protocol that is used to transport SCSI commands across a TCP/IP network. This allows a system to access storage across a network just as if the system were accessing a local physical disk. In an iSCSI network, the client access the storage is called the initiator. The remote storage that the client accesses is called the target .

LDAP

Lightweight directory access protocol (LDAP) is a networking protocol that organizes access to data in a directory tree structure.

KDC

Key distribution center

metadata

Information that describes a file, such as the file's name, size, location, and permissions.

metadata server

The node that coordinates updating of metadata on behalf of all nodes in a CXFS cluster.

MSP

Media-specific process, the daemon-like process in DMF by which data blocks are copied onto alternate media, and which assigns keys to identify the location of the migrated data.

name service

Application that manages the information associated with network users.

NAS client

Computer running a program that accesses the storage server.

NFS

Network file system.

NIC

Network interface card.

NIS

Network information service (NIS) is a network lookup service that provides a centralized database of information about the network to systems participating in the service.

node

A node is an operating system (OS) image, usually an individual computer. (This use of the term node is different from the NUMA definition for a brick/blade on the end of a NUMAlink cable.) See also client-only node .

non-dual-resident file

A file in DCM that is not a cache-resident copy of a migrated file. It must be migrated to tape before it can be removed.

NTP

Network Time Protocol.

physical volume element

The combination of multiple RAID disk drives into a single logical unit.

RAID

Redundant array of independent disks.

RAID 5

A level of RAID that uses block-level striping and distributed parity.

resource

In the context of the Appliance Manager interface, a resource is something that is monitored and managed by Appliance Manger (such as network interfaces or DMF).

Serial ATA (SATA)

Serial advanced technology attachement storage interface connection.

service

Task performed by the storage server.

shadow file

A file that is protected from all access by non- root users and stores the encrypted passwords.

ssh

A tool that is used to communicate between nodes in the cluster. See http://www.openssh.com/ .

smart host

The gateway server where email should be delivered.

snapshot

See XVM snapshot.

system time

Time the CPU spent executing kernel code. This is usually dominated by NFS file serving and accessing data from disks.

tape library slot usage

The number of slots used by DMF, other applications, or vacant.

target

The storage that appears to the initiator as a disk drive in an iSCSI network.

TMF

Tape Management Facility.

VG

Volume group, one of the components of a DMF library server. A volume group is responsible for copying data blocks onto alternate media.

wait time

Time when a CPU was forced to do nothing while waiting for an event to occur. Typical causes of wait time are filesystem I/O and memory swapping.

XFS

A filesystem implementation type for the Linux operating system. It defines the format that is used to store data on disks managed by the filesystem.

XVM snapshot

Virtual point-in-time image of a filesystem. Snapshot copies are not actual media backup for a filesystem.

YaST

An operating system setup and configuration tool.