User Guide

Glossary: Dell OpenManage Storage Consolidation User's Guide

Glossary: Dell OpenManage™ Storage Consolidation User's Guide

A • B • C • D • E • F • G • H • I • J • K • L • M • N • O • P • Q • R • S • T • U • V • W • X • Y • Z

The following list defines or identifies technical terms, abbreviations, and acronyms used in or relevant to this document.

A

alias server
A fabric software facility that supports multicast group management.

block
A typical unit of disk storage consisting of a small number of sectors. This term usually refers to the fundamental unit of storage provided by an operating system. See also block size and striping.

block size
The size of a block. See also block and striping.

C

CIM
Acronym for common information model.

Class 2
In Class 2 service, the fabric and destination N_Port provide connectionless service with notification of delivery or nondelivery between the two N_Ports.

Class 3
Class 3 service provides connectionless service without notification of delivery between N_Ports. The transmission and routing of Class 3 frames is the same as for Class 2 frames.

Class F
A class of service used for interswitch control traffic. It provides connectionless service with notification of delivery or nondelivery between two E_Ports.

community (SNMP)
An SNMP community is a relationship between an SNMP agent and a set of SNMI managers that defines authentication, access control, and proxy characteristics.

control space
The Storage Consolidation control space is a fibre switch-independent software construct. It contains all the storage groups, servers, Dell™ PowerVault™ enclosures, and virtual disks in the SAN.

D

DAE
Abbreviation for Disk Array Enclosure.

DPE
Abbreviation for Disk Processor Enclosure.

DMI
Abbreviation for Desktop Management Interface.

directory
Directories help keep related files organized on a disk in a hierarchical, "inverted tree" structure. Each disk has a "root" directory; additional directories that branch off of the root directory are called subdirectories. Subdirectories may contain additional directories branching off of them.

F

fibre switch zone
A fibre switch zone (FS zone) is a user-defined relationship between server and storage. For example, you can set up one FS zone where server A is associated with storage unit A, another FS zone where server A is associated with storage unit B, and a third FS zone where server B is associated with storage unit B. FS zones are different from the storage groups displayed in Storage Consolidation Administrator. In this example, you end up with only two storage groups in the Storage Consolidation Administrator window:

Storage group 1: containing server A, storage unit A and storage unit B
Storage group 2: containing server B and storage unit B

G

guarding
A type of data redundancy that uses a set of physical drives to store data and a single, additional drive to store parity data. Using guarding, the user’s data is protected from the loss of a single drive. Guarding is sometimes preferred over mirroring because it is more cost effective in systems with a very high storage capacity. However, guarded configurations are significantly slower for application programs that frequently write to the array, because each attempt to write to the array requires multiple read and write commands to maintain the parity information. If this is a problem, mirroring or duplexing is a better choice. See also mirroring, RAID 4, and RAID 5.

GUI
Acronym for graphical user interface.

I

I/O
Abbreviation for input/output. The keyboard and a printer, for example, are I/O devices. In general, I/O activity can be differentiated from computational activity. For example, when a program sends a document to the printer, it is engaging in I/O activity; when the program sorts a list of terms, it is engaging in computational activity.

J

JRE
Abbreviation for Java Runtime Environment.

JVM
Abbreviation for Java virtual machine.

L

LUN
Acronym for logical unit number. A LUN is the result of performing a RAID level binding on multiple physical disk(s). For example, you can create a LUN by doing RAID 5 binding on three physical disks in a PowerVault system. From that point on, you no longer have direct access to those physical disks and all I/O operations will go through the resulting LUN. The RAID software controlling the LUN will then direct I/O to individual physical disks according to its internal algorithm.

M

MB
Abbreviation for megabyte(s). A megabyte equals 1024 kilobytes or 1,048,576 bytes; however, when referring to hard-disk drive storage, the term is often rounded to mean 1,000,000 bytes.

MHz
Abbreviation for megahertz.

mirroring
A type of data redundancy that uses a set of physical drives to store data and one or more sets of additional drives to store duplicate copies of the data. Mirroring is the preferred data redundancy technique in lower-capacity systems and in systems where performance is extremely important. See also guarding, RAID 1, and RAID 10.

N

NDS
Abbreviation for Novell� NetWare� Directory Service.

NIC
Acronym for network interface controller.

NLM
Abbreviation for NetWare Loadable Module.

NNM SE
Abbreviation for Network Node Manager Special Edition.

NTFS
Abbreviation for the NT File System option in the Microsoft� Windows NT� operating system.

O

out-of-band
Communications that use a remote assistance card to remotely manage a server using a modem or an integrated NIC on the card. The out-of-band path is used for remote management of a server or for accessing server information when the server or network is down.

P

PowerVault storage products
A PowerVault product is a Dell storage device. Some examples are tape drives, disk arrays, and switches/routers. The storage devices that are used together with Storage Consolidation are the PowerVault 650F and the optional PowerVault 630F. The PowerVault 650F contains a Fibre Channel RAID controller that can handle up to 120 Fibre Channel disk drives. To implement the storage area network, PowerVault 50F/51F Fibre Channel switches are needed. The Fibre Channel switches allow multiple Fibre Channel devices (servers and storage) to communicate through a Fibre Channel switched network.

parameter
A value or option that you specify to a program. A parameter is sometimes called a switch or an argument.

R

RAID
Acronym for redundant array of independent disks. This phrase was introduced by David Patterson, Garth Gibson, and Randy Katz at the University of California at Berkeley in 1987. The goal of RAID is to use multiple small, inexpensive disk drives to provide high storage capacity and performance while maintaining or improving the reliability of the disk subsystem.

Patterson, Gibson, and Katz described five different methods, which are known as RAID levels 1 through 5. Each level uses one or more extra drives to provide a means of recovering data lost when a disk fails, so that the effective failure rate of the whole disk subsystem becomes very low.

Recently, Katz has defined a sixth method, RAID 6, which improves reliability even further, and a configuration that provides no data recovery. It has become known as RAID 0.

RAID 0
RAID 0 is commonly called striping. This was not originally defined as a RAID level but has since come into popular use. In this array configuration, data is written sequentially across the available disks and no redundancy is provided. RAID 0 configurations provide very high performance but relatively low reliability. RAID 0 is the best choice when DSA controller cards are duplexed. See also striping.

RAID 1
RAID 1 is commonly called mirroring. RAID 1 also uses striping, so RAID 1 may be regarded as the mirroring of RAID 0 configurations. RAID 1 is the best choice in high-availability application programs that require high performance or relatively low data capacity. See also mirroring, RAID 10, and striping.

RAID 4
RAID 4 is commonly called guarding. It uses data striping, like RAID 0, but adds a single, dedicated parity drive. The parity data stored on this drive can be used to recover data lost from a single failed drive. RAID 4 configurations write data slowly because parity data has to be generated and written to the parity drive, and the generation of the parity data frequently requires reading data from multiple physical drives. See also guarding and striping.

RAID 5
RAID 5, like RAID 4, is commonly called guarding. RAID 5 is identical to RAID 4, except that the parity data is distributed evenly across all physical drives instead of a parity drive. In configurations using a large number of physical drives in which a large number of simultaneous small write operations are being performed, RAID 5 offers potentially higher performance than RAID 4. RAID 4 and RAID 5 configurations are appropriate in high-availability application programs where performance is less critical or where high data capacity is required. See also guarding.

RAID 10
RAID 10 is a mirroring technique in which data is duplicated across two identical RAID 0 arrays or hard-disk drives. All data on a physical drive in one array is duplicated, or mirrored, on a drive in the second array. Mirroring offers complete redundancy of data for greater data security. See also mirroring, RAID 1, and striping.

RAID level
A number indicating the data storage scheme used on a hard-disk drive.

S

SNMP
Abbreviation for Simple Network Management Protocol.

striping
In composite drivers with two or more physical drives, the drive array subsystem uses a method of data storage called striping. With this method, data is divided into a series of pieces called blocks and each data block is stored on a different physical drive. When each drive contains a block of data, the process starts over with the first physical drive. By carefully selecting the size of the data block, the chance that the information needed can be read from or written to multiple physical drives at once is increased, greatly increasing the performance of the composite drive. See also block, block size, and RAID.