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製品 | 用語集
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Adapter
Hardware that allows one device to interact with another. Typically, an adapter enables a computer to access peripheral devices or networks. In common SAN architecture, the Host Bus
Adapter enables connection to the SAN.
Agent
In the client/server an agent is the part of the system that performs information preparation and exchange on behalf of a client to the server application. In SNMP, the agent is a software layer that gathers SNMP data and transmits it to the SNMP management application.
AIM (Asynchronous IP Mirroring)
AIM is the DataCore SANsymphony option that implements asynchronous mirroring over any IP connection (LAN/MAN/WAN) without requiring any external translation devices or proprietary network protocols. AIM supports one-to-many, many-to-one and bi-directional modes of operation and is extremely resilient with respect to link outages and other transient network errors.
AIM Client
Enables any Windows host (server, desktop, laptop etc.) to create an asynchronous mirror of its direct attached hard drives to a Powered By DataCore SAN over any IP connection. There is no requirement for the Windows host to have any direct connection to a SAN making AIM client ideal for isolated servers and other hosts that require centralized backup and disaster recovery services.
Alarm vs. Alert
In the most precise usage, an alarm is an off-normal condition (or state) indicating a performance or equipment degradation or failure. An alert is an indication of a change (or status) from a normal to an alarm condition or vice versa. However, the term "alarm" is often used where "alert" would be more accurate. For example, "alarm dialout" actually occurs on changes from alarm to normal as well as from normal to alarm.
Application Programmer Interface (API)
A well defined set of program interfaces (typically subroutine calls) used by developers to create software that communicates with an application or piece of hardware .
Asynchronous Mirror
A mirrored volume where the target lags behind the source by some arbitrary number of I/O operations. The extent of the lag is typically governed by the amount of I/O taking place on the source and the bandwidth available between the source and target mirrors. Asynchronous mirrors are often used for long distance data replication where the time taken to transmit a write request from source to target would present a significant bottleneck for the application server issuing the write.
Asynchronous Operations
Operations can occur without having to be synchronized with each other in respect to time. Asynchronous operations may overlap in time. The concept of asynchronous I/O operations is central to the use of independent access arrays in throughput-intensive applications.
Availability
The probability that a system is available at a given point in time. Averaged over time, this function expresses the expected percentage of time a system is available to do useful work.
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Backup Server
A computer and storage system that provides backup and restore services for the network as a network resource.
Bus
The main communication avenue in a computer; an electrical pathway along which signals are sent from one part of the computer to another, for example from the CPU to the hard disk.
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Cache
Temporary storage for information or instructions, typically it is faster than primary storage. Retrieval of data from cache is much faster than getting it directly from primary storage. Increasing cache improves performance. Cache is widely used at all levels of computer hardware from processor caches integrated in the CPU to disk and I/O caches implemented in system memory.
Cache Memory
A portion of memory dedicated to collecting and holding related data until a processing or a storage module is ready to process it. The intent is to improve the overall system performance. Cache for a disk drive is usually implemented as fast semiconductor memory.
Channel
A point-to-point link, the main task of which is to transport data from one point to another. An electrical path for the transfer of data and control information between a disk and a disk controller.
Client
[1] A recipient of services in a client/server application. Clients can be workstations or other servers. [2] The part of software which Users interact with. [3] A software program used to contact and obtain data from a "server" software program on another computer-often across a great distance. Each "client" program is designed to work specifically with one or more kinds of server programs, and each server requires a specific kind of client program.
Client/Server
[1] The relationship between machines in a communications network. The client is the requesting machine, the server the supplying machine. Also used to describe the information management relationship between software components in a processing system. [2] A system architecture in which one or more programs (clients) request computing or data services from another program (server).
CIM (Common Information Model)
An object oriented standard for developing a model of a complex hardware device such as a server or a storage array in order to integrate that hardware device with a standard management application. CIM is developed and promoted by the industry body know as the Distributed Management Task Force (DMTF).
Controller
A physical module that interprets signals sent between the host processor and a peripheral device.
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Data Accessibility
A term defining the system requirements for network storage as continuous access to files and data, high performance and protection from data loss.
Data Availability
An application's ability to access correct data in a timely manner. Usually implies continued data availability in the presence of a component failure.
Data Compression
Reducing the amount of "space" required to store data. Methods include replacing blank spaces with a character count, or replacing redundant data with shorter stand-in "codes." No matter how data is compressed, it must be decompressed before it can be used.
Data Reliability
Expressed in Mean Time to Data Loss (MTDL), is the average length of time over which data stored in a disk subsystem can be correctly retrieved.
Data Transfer Rate
The rate at which data is transferred to or from the storage media. For disk devices, Data Transfer Rate is usually measured in millions of bytes per second (Mbytes/second).
Direct Access Storage Device (DASD)
Any online data storage device. A disc, drive or CD-ROM player that can be addressed is a DASD.
Disaster Protection
A set of rules and procedures that allow a computer site to be put back in operation after a disaster has occurred. The moving of backups off-site constitutes the minimum basic precaution for disaster protection. The remote copy is used to recover data when the local storage is inaccessible after the disaster.
Disk array
An arrangement of two or more disk drives with control software. Disk arrays typically include a RAID controller that presents the disks' storage capacity to hosts as one or more logical units (LUNs).
Disk Mirroring
A fault-tolerant technique that writes data simultaneously to two locations (usually hard disks, but could be logical volumes in different arrays.) The disks operate in tandem, constantly storing and updating the same files. Mirroring alone does not ensure data protection. If both hard drives fail at the same time, you will lose data.
Disk Striping
A type of disk mapping within an array where consecutive stripes of data are mapped round-robin to consecutive disks. In its simplest form this is called RAID Level 0 and is designed to provide high I/O performance at low cost, but provides lower net data reliability than any of its member disks. More complex implementations such as RAID levels 2,3,4 & 5 add some sort of error correction or parity data to address the reliability issue.
Disk Subsystem
A collection of disks and the hardware required to connect them to one or more host computers. The hardware may include an intelligent controller or the disks may attach directly to a host computer's I/O bus adapter.
DWDM (Dense Wave Division Multiplexing)
DWDM is a technique used to multiplex several signals over the same Fibre link by encoding each signal using a different wavelength of light.
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Fabric
A Fibre Channel network consisting of multiple devices interconnected by one or more switches that use Fibre Channel methodology to link nodes and route frames.
Fabric Switch
In this category or switch, any port on any switch can provide (subject to bandwidth availability) full speed access to any other port on the network. The network consists of a fabric of linked switches.
Fibre Channel (FC)
A high speed network transmission technology that is capable of transferring data between two ports at up to 1 gigabit/second (or 2 gigabits/second with the latest products) over a distance of up to 10 kilometers. Fibre Channel is largely credited with enabling the SAN model due to its performance and connectivity attributes. Fibre Channel supports point to point, arbitrated loop, and switched topologies.
Fibre Channel Arbitrated Loop (FCAL)
Arbitrated loop one of the possible physical topologies of Fibre Channel. In this topology, the Fibre Channel is connected in a loop with devices all connecting to the loop. It can be thought of as a similar structure to a token ring network. Up to 126 nodes can be connected to the loop.
Fibre Channel Topology
A number of possible topologies exist for the connection of Fibre Channel. One is point-to-point, where a direct connection is made between nodes on the Fibre Channel. Another is Arbitrated Loop where multiple nodes can be connected together. Lastly, there is a Fibre Channel Fabric topology allowing for multiple loops and point-to-point connections to be combined into networks using switches.
File System (FS)
Part of an OS that tracks, retains and monitors all files. The FS can be accessed by other parts of the OS along with applications via well-documented APIs.
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Gigabyte, Gbyte (GB)
[1] A billion (slightly more) bytes of data, or a thousand megabytes. [2] Shorthand for 1,000,000,000 (10^9) bytes. Some prefer to use the (10^9) convention commonly found in I/O-related literature rather than the 1,073,741,824 (2^30) convention sometimes used in describing computer system memory.
Gigabit, Gbit (Gb)
[1] A billion (slightly more) bits of data (128MB.) Most commonly used when describing a transmission speed, for example modern Fibre Channel links are capable of transmitting 2Gbit/s of data.
GBIC (Gigabit Interface Connector)
A device used to interface between the wire that carries a Gbit signal and the switch or HBA connected to it. In SANs, there are three types, copper (used when the wire is copper), shortwave (used for relatively short distance connections over optical cable that use a short wavelength laser) and Longwave (used for long haul connections where a longer wavelength laser is used).
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High availability
The ability of a system to function without interruption and with greater reliability than its individual components are capable. High availability is most often achieved through failure tolerance.
Host Bus Adapter (HBA)
A hardware card that resides on the computer's bus and provides a connection to storage devices.
Host Computer
Any computer system to which disks are directly attached and accessible. Mainframes, and servers, as well as workstations and personal computers, can all be considered host computers, as long as they have disks attached to them.
Hot Spare
Or Online spare. A drive that is present in the system but normally unused until another drive fails, at which time the hot spare is automatically substituted for the failed drive.
Hot Swap
The substitution of a replacement unit (RU) in a disk subsystem for a defective one, where the substitution can be performed while the subsystem is running (performing its normal function). Hot swaps are manually performed by humans.
Hub
This is a simple connectivity device that allows for devices to be connected to a fibre channel loop by being attached to a hub port. The advantage of this is that failures of a single device on the loop can be isolated from the other ports on the loop. However, unlike a Fibre Channel switch, the aggregate bandwidth of the hub is still that of a single Fibre channel loop.
Hyperthreading
Hyperthreading is a technique used by Intel in its latest PEntium 4 and XEON processors where a single physical processor is presented to the operating systems as two logical processors.
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I/O Driver
A host computer software component (usually part of the operating system) whose function is to control the operation of a peripheral controllers or adapter attached to the host computer. I/O drivers communicate between applications and I/O devices, and in some cases may participate in data transfer, although this is rare with disk drivers, since most disk adapters and controllers contain hardware for data transfer.
I/O Load
The sequence of I/O requests made to one or more disk subsystems by the host computing environment. The host computing environment includes both applications and host overhead functions, such as swapping, paging, and file system activity.
I/O Operations per Second (IOPS)
A generic measure of I/O performance. To be meaningful, the type and operation mixture of I/O must be specified as well, such as read IOPS.
Incremental Backup
An operation that backs up all data that has been modified or added since a given date. The date is usually the date of the last full or incremental backup.
iSCSI
An alternative to Fibre Channel that allows the transmission of disk block I/O over standard TCP/IP and Ethernet networks.
InterSDS Network Mirroring
This is the SANsymphony implementation of synchronous mirroring.
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JBOD
Just a Bunch of Disks. Refer to a disk drive configuration in which there is no redundancy and where each drive is treated as a separate, independent unit with no data striping across the disks.
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Latency
A measurement of the time taken to send a frame between two locations. Low latency is a fundamental requirement for storage applications and is typical of I/O channel technologies. Fibre Channel connections are characterized by low latency. In a disk drive, latency relates to the disks rotational speed and must be considered in determining a disk drives total access time.
Local Area Network (LAN)
[1] A network covering a relatively small geographic area (usually not larger than a floor or building). Compared to WANs, LANs are usually characterized by relatively high data rates. [2] Network permitting transmission and communication between hardware devices, usually in one building or complex. [3] High-speed transmissions over twisted pair, coax, or fibre optic cables that connecting terminals, personal computers, mainframe computers, and peripherals together at distances of about one mile or less.
Logical Disk
A set of contiguously addressed member disk blocks that is part of a single virtual disk-to-member disk mapping. Logical disks are used in some arrays implementations as constituents of logical volumes or partitions.
Logical Unit Number (LUN)
The SCSI identifier of a logical unit (which corresponds to a virtual disk) of a storage device.
Logical Volume
A virtual disk made up of one or more logical disks. Also called a virtual disk, volume set, or partition.
LUN Masking
LUN masking is a technique using software (run on each application server) that "hides" the LUNs of disks that the application server is not permitted to access.
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Mapping
A term used to describe the process of assigning a disk volume to an application server.
Mean Time Between Failures (MTBF)
A measure of equipment reliability, the higher the MTBF, the more reliable the equipment.
Metadata
Data that describes data. In disk arrays, metadata often consists of items such as array membership, member segment sizes, descriptions of logical disks and partitions, and array state information.
Mirroring
A form of RAID in which the array controller (or operating system software) maintains two or more identical copies of data on separate storage devices with the purpose of protecting data resources and maintaining business operations. Also known as RAID Level 1 and disk shadowing.
MultiPath I/O (MPIO)
MPIO is a vendor independent solution for the management of alternate paths within the storage network. MPIO was introduced by Microsoft for Windows 2003 Server and is also available for Windows 2000 Server.
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Network
[1] A collection of computers and other devices able to communicate with each other over some network medium. [2] An aggregation of interconnected nodes, workstations, file servers, and/or peripherals, with its own protocol that supports interaction.
Network Managed Volume (NMV)
Network Managed Volumes (NMVs) are extended virtual devices (each NMV can be up to 2TB in size) where the capacity presented to clients can exceed the physical resources currently available in the storage pool. SANsymphony automatically allocates blocks of storage from a central pool to provide just enough space to these NMV LUNs. As the pool of physical storage is depleted, additional storage resources are added to the pool, ensuring that sufficient capacity is available to meet new requests. Because storage resources are only allocated to meet actual storage requirements, NMVs are extremely effective at raising overall storage capacity utilization. For example, the host may have 200GB of data stored on a 2TB NMV; in that case, SANsymphony will only use 200GB of physical storage to hold the data associated with that LUN.
Network Storage Resource
A storage pool that can be accessed by every client in the network. Its access is completely transparent to the user, whether the storage is online or nearline.
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Operating System
Collection of programs that, taken together, manage the hardware and software; it is the operating system that makes the hardware usable, providing the mechanisms that application programs use to interact with the computer.
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Partition
A virtual disk. The term partition is most often used when a redundancy group is presented to a host operating environment as more than one virtual disk or volume set. Also used in complex arrays with dynamic mapping to denote a collection of redundancy groups dedicated to providing the storage for a subset of an array's virtual disks.
Proxied Volumes (PVs)
Proxied volumes enable SANsymphony's advanced services to operate on top of pre-formatted volumes without modifying the structure of existing data. PVs are most often used as a temporary measure to ensure that conventional direct access to the data can resume if SANsymphony software was no longer in control or as a means for migrating data from existing storage.
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RAID (Redundant Array of Independent (or Inexpensive) Disks)
A disk array in which part of the physical storage is used to store redundant information about other parts of the physical storage. The redundant information enables recovery of data in the event that one of the disks or the access path to it fails. The "I" in RAID was originally Inexpensive in the Chen/Patterson paper from Berkeley that defined the term.
RAID Level
A number designating the general configuration of an array. RAID configurations are defined and generally accepted from level 0 through 5.
RAID 0
A logical volume consisting of two or more disk drives (or drive partitions) where data is laid out across the stripe in round robin fashion. Sometimes referred to as disk striping.
RAID 1
A logical volume consisting of two disk drives (or drive partitions) where data written to the first drive is also written to the second drive. Sometimes referred to as disk mirroring.
RAID 2
A logical volume consisting of 36-40disk drives (or drive partitions) where data is is broken into single bits and written one "bit" at a time out across the stripe 32 bits at a time. The additional drives are used to store an error correction code that can be used to reconstruct data in the event of a drive failure. Because of the high number of drives required, RAID 2 is rarely implemented in commercial systems.
RAID 3
A logical volume consisting of three or more disk drives (or drive partitions) where data is broken into bytes and laid out across the N-1 drives in the stripe in round robin fashion. The additional drive holds parity byte produced by performing an Exclusive OR (XOR) operation on the bytes written to the preceding N-1 drives. The parity byte in conjunction with the bytes on surviving drives can be used to reconstruct data in the event of a drive failure. RAID 3 provides very high data throughput and has been used primarily in applications like video editing.
RAID 4
A logical volume consisting of three or more disk drives (or drive partitions) where data is broken into blocks and laid out across the N-1 drives in the stripe in round robin fashion. The additional drive holds parity block produced by performing an Exclusive OR (XOR) operation on the blockswritten to the preceding N-1 drives. The parity block in conjunction with the blocks on surviving drives can be used to reconstruct data in the event of a drive failure. RAID 4 is rarely implemented on commercial RAID controllers because it suffers from poor performance on writes because of the bottleneck presented by the parity drive.
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Drive 1
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Drive 2
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Drive 3
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Block 1
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Block 2
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Block 1 XOR Block 2
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Block 3
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Block 4
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Block 3 XOR Block 4
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Block 5
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Block 6
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Block 5 XOR Block 6
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RAID 5
A logical volume consisting of three or more disk drives (or drive partitions) where data is broken into blocks and laid out across the all drives in the stripe in round robin fashion. In addition to the data blocks, a parity block produced by performing an Exclusive OR (XOR) operation on the blocks written drives. The distinction between RAID 4 & RAID 5 is that the parity block is rotated across the drives:
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Drive 1
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Drive 2
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Drive 3
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Block 1
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Block 2
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Block 1 XOR Block 2
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Block 3 XOR Block 4
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Block 3
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Block 4
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Block 5
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Block 5 XOR Block 6
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Block 6
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The parity block in conjunction with the blocks on surviving drives can be used to reconstruct data in the event of a drive failure. By rotating the parity across all drives in the stripe, the bottleneck presented by the parity drive in RAID 4 is eliminated.
RAID 0+1
A combination where a RAID 0 stripe is mirrored to a second stripe of identical size.
Random I/O
An I/O load where consecutive Read or Write requests are randomly distributed across the drives. Random I/O is characteristic of I/O request-intensive applications such as databases.
Redundancy
The utilization of additional modules that are not necessary for a normal system operation. These modules are substituted for failed components (or can perform the same function as), allowing the system to remain operational.
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Scalable
Capable of growing through additions of modular increments, without necessitating major modifications to the original system. In a storage context, a scalable system is capable of efficiently handling the requirements from a small system to a large system, in terms of capacity, performance, availability, connectivity, and/or manageability.
Scalability
The ability of the storage system to increase resources and performance in proportion to requirements of the applications with minimal disruption.
Security Features
Security features include operator access privileges, authorization levels, and password control to limit access to unauthorized files and data.
Serial Storage Architecture (SSA)
A rival to Fibre Channel, SSA was developed (and is still used in some products by IBM. SSA shares many of the same attributes as Fibre Channel providing a storage interface designed for network computing, enabling simultaneous communication between multiple devices, subsystems, and local host processors throughout the open systems environment. SSA has largely been eliminated in the market by the acceptance of Fibre Channel and by advances in the SCSI specification.
Server
A computer which is dedicated to one task. A database or directory server would be responsible for responding to a User's search request, returning the list of stored documents that meets with the parameters of the request.
Small Computer System Interface (SCSI)
An industry standard for connecting peripheral devices and their controllers to a microprocessor. SCSI defines both hardware and software standards for communication between a host computer and peripheral. Computers and peripheral devices designed to meet SCSI specifications should work together. A single SCSI interface can control as many as sixteen different hard disks, optical disks, tape drives and scanners, without siphoning power away from the computer's main processor. Formerly known as SASI (Shugart Associates Systems Interface). SCSI has been developed from an original specification capable of 5MB/s throughput to the latest Ultra3 interfaces capable of up to 320MB/s.
Snapshot
A copy of data made at a specific point in time, also referred to as "point-in-time snapshot." Snapshots can be used to allow two application servers to access the same set of data at once, for example, to backup data to a tape drive.
SMI (Storage Management Initiative)
SMI is an attempt by SNIA to promote a standard model and method for the management of components in a storage network. SMI is based on a document published in 2002 called "The BlueFin Specification" and seeks to leverage the CIM and WBEM models as the core of the new storage management standard.
SNMP (Simple Network Management Protocol)
SNMP is a set of standards developed within the networking industry to facilitate the passing of information from devices such as routers, servers and switches to a management application.
SPC (Storage Performance Council)
SPC is an open industry forum that seeks to define and propagate standard benchmarks for storage subsystems that will allow customers to make "apples to apples" performance comparisons of different storage solutions.
SSA (Serial Storage Architecture)
A high speed serial interface designed and marketed by IBM.
SSF (Supported Solutions Forum)
SSF is a SNIA supported body composed of vendors who work together to create certified solutions consisting of SAN products from multiple vendors.
Static Virtual Volumes (SVVs)
SVVs are the original SANsymphony abstraction created by manually partitioning unformatted disks using the Windows Logical Disk Manager services, and later mapping the raw partitions into virtual images of the same size, usually with the SAN Manager GUI.
Storage Area Network (SAN)
Simply put, this is the evolutionary step of connectivity provided by a support (e.g., Fibre Channel) between host and storage. This connectivity provides a true network of storage devices and the hosts that access the storage. A centralized resource of disk drives and disk subsystems connected by a Storage Area Network to application servers.
Storage Capacity
Amount of data that can be contained in an information storage device or main memory, generally expressed in terms of bytes, characters or words.
Storage Density
Usually refers to recording density (bits/inch (bpi), tracks/inch (tpi), or a combination of both).
Storage Domain Server (SDS)
SDS is the commonly used DataCore term for a server running the SANsymphony software package.
Storage Domain
DataCore defines a storage domain as a grouping of storage resources, infrastructure components and application servers that are grouped together logically and managed with respect to capacity and performance. For example the systems, storage and infrastructure used by the Accounting Department might be grouped into one storage domain, while the resources used by Human Resources might form another storage domain.
Storage Media
The physical device itself, onto which data is recorded. Magnetic tape, optical disks, floppy disks are all storage media.
Storage pool, pooling
A centralized resource of disk drives and disk subsystems connected by a
Storage Area Network to application servers.
Storage Subsystem
A disk subsystem (q.v.) whose intelligent controller or I/O bus adapter is capable of attaching other forms of mass storage such as CD-ROMS or tape transports.
Storage Tunneling Protocol over IP (STP/IP)
A DataCore implementation of block storage over IP derived from an early draft of the iSCSI spec. The main difference between iSCSI and STP/IP is that STP/IP allows the host to cache I/Os to local disk to improve performance.
Storage Virtualization
Storage virtualization abstracts the rigid characteristics of physical storage devices into more flexible and manageable virtual (logical) objects. To the user or application, a virtual disk appears to be a well-behaved device. To the storage administrator, ideal virtual disks can be reassigned effortlessly without making physical modifications to the hardware or disrupting running applications. Virtualization continues to be driven by the necessity to simplify storage management as storage capacity and storage devices proliferate.
Striped Array
The collection of disks comprising an array which implements the RAID Level 0 or disk striping (q.v.) mapping technique.
Striping
Short for disk striping (q.v.); also known as RAID Level 0. The process of recording data across multiple disks rather than to a single drive. Data is divided into segments each of which is written to successive drives. Striping is also referred to as RAID 0.
Switch
A network infrastructure component to which multiple nodes attach. Unlike hubs, switches maintain full bandwidth capacity to all attached devices. They also have the ability to rapidly switch node connections from one to another.
Synchronous Mirror
A mirrored volume where the target and source volumes are kept in "lockstep" with respect to I/O operations, this commonly referred to as a RAID-1 configuration.
System Disk
The disk on which a system's operating software is stored. The system disk is usually the disk from which the operating system is bootstrapped (initially loaded into memory). The system disk frequently contains the system's swap and/or page files. It may also contain libraries of common software shared among several applications.
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Tape Backup
Making mag tape copies of hard disk and optical disc files, for disaster recovery.
Terabyte (TB)
[1] A trillion (slightly more) bytes of data, or a thousand gigabytes. [2] Shorthand for 1,000,000,000,000 (10^12) bytes. Some prefer to use the (10^12) convention commonly found in I/O-related literature rather than the 2^40 convention sometimes used in describing computer system memory.
Throughput
The speed with which data can be transferred from a storage device to the host (or vice-versa) typically expressed in megabytes/sec(MB/S).
Throughput-Intensive
A characterization of applications. Also known as request-intensive. A throughput-intensive application is an I/O intensive where the key performance characteristic is MB/s rather than I/Os per second (IOPS.)
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Unformatted Capacity
Storage capacity of disk drives prior to formatting; also called the gross capacity.
UNIX
A general-purpose, multi-user, multitasking, operating system invented by AT&T. UNIX is powerful and complex, and needs a computer with a large amount of RAM memory to support its power. UNIX allows a computer to handle multiple users and multiple programs simultaneously. And it works on many different computers, which means you can often take applications software and move it, with little changing, to a bigger, different computer, or to a smaller, different computer. This process of moving programs to other computers is known as "porting." UNIX uses TCP/IP as its standard communications protocol.
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Value Added Reseller/Value Added Dealer (VAR/VAD)
Companies that buy equipment from computer manufacturers, add some of their own software and possibly some peripheral hardware to it, and then resell the whole computer system to end users.
Virtual disk, virtual volumes, virtualization
A storage resource that is made to look and behave like a complete disk volume to an operating system, even if it is only a disk partition or stripe set.
Virtual Disk Service (VDS)
A feature introduced in Windows Server 2003, VDS simplifies the management of volumes on the host and provides a vendor independent way of requesting new storage resources from the underlying storage network.
Virtual Snapshot Service (VSS)
A feature introduced in Windows Server 2003, VSS is a vendor independent mechanism to simplify the process of synchronizing applications, storage snapshot services and backup applications. Any VSS enabled application will be able to request a snapshot from any VSS enabled storage, similarly, a backup application will be able to communicate to an application via VSS to request the creation of a snapshot.
Volume Management
The ability to make two distinct disk drives or tape subsystems appear to an operating system as one logical system. Therefore, if you have four disk drives, you can structure those four disk drives as one large disk farm enabling data to be written to the entire disk farm at the same time.
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WBEM (Web-Based Enterprise Management) Initiative
Web-Based Enterprise Management (WBEM) is a set of management and Internet standard technologies developed to unify the management of enterprise computing environments. WBEM provides the ability for the industry to deliver a well-integrated set of standard-based management tools leveraging the emerging Web technologies. The DMTF has developed a core set of standards that make up WBEM, which includes a data model, the Common Information Model (CIM) standard; an encoding specification, xmlCIM Encoding Specification; and a transport mechanism, CIM Operations over HTTP.
Wide Area Network (WAN)
[1] A network which encompasses interconnectivity between devices over a wide geographic area. Such networks would require public rights-of-way and operate over long distances. [2] A network linking computers, terminals and other equipment covering an area larger than a single building or campus.
Write Cache
A cache segment used to accumulate data before writing to the drive on the theory that a single large Write operation is more efficient than several smaller transfers.
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Zoning
This is the term used by some switch companies to denote the division of a SAN into sub nets that provide different levels of connectivity or addressability between specific hosts and devices on the network. In effect routing tables are used to control access of hosts to devices. This zoning can be performed by cooperative consent of the hosts or can be enforced at the switch level. In the former case, hosts are responsible for communicating with the switch to determine if they have the right to access a device.
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