Glossary of terms

Ethernet – Is an IEEE 802.3 standard for LAN (local area networks) that allows multiple computers to connect on the same network using IP as the communication protocol between server - server, server - workstation, workstation - workstation, server - data storage, workstation - data storage.

SCSI – Small Computer Systems Interface is a way for all data storage devices to communicate over a common protocol standard.

iSCSI – An IP-based standard for linking data storage devices over a network and transferring data by carrying SCSI commands over IP networks. iSCSI supports a Gigabit Ethernet interface at the physical layer, which allows systems supporting iSCSI interfaces to connect directly to standard Gigabit Ethernet switches and/or IP routers. When an operating system receives a request it generates the SCSI command and then sends an IP packet over an Ethernet connection. At the receiving end, the SCSI commands are separated from the request, and the SCSI commands and data are sent to the SCSI controller and then to the SCSI storage device. iSCSI will also return a response to the request using the same protocol.

IP – Internet Protocol. The Internet Protocol (IP) provides a best effort network layer service for connecting computers to form a computer network

LAN - The Local Area Network (LAN) is by far the most common type of data network. As the name suggests, a LAN serves a local area (typically the area of a floor of a building, but in some cases spanning a distance of several kilometres). Typical installations are in industrial plants, office buildings, college or university campuses, or similar locations. In these locations, it is feasible for the owning Organisation to install high quality, high-speed communication links interconnecting nodes. Typical data transmission speeds are one to 100 megabits per second.

WAN - The term Wide Area Network (WAN) usually refers to a network which covers a large geographical area, and use communications circuits to connect the intermediate nodes. A major factor impacting WAN design and performance is a requirement that they lease communications circuits from telephone companies or other communications carriers. Transmission rates are typically 2 Mbps, 34 Mbps, 45 Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more).

SAN – The term Storage Area Network (SAN) is a high-speed special-purpose network (or sub-network) that interconnects different kinds of data storage devices with associated data servers on behalf of a larger network of users. Typically, a storage area network is part of the overall network of computing resources for an enterprise.

Block Level - In data storage, a block is a group of records on a storage device. Blocks are manipulated as units. For example, disk drives often read and write data in 512- byte blocks.

Gigabyte – 2 to the 30th power (1,073,741,824) bytes. One gigabyte is equal to 1,024 megabytes. Gigabyte is often abbreviated as G or GB.

NAS - A network attached storage (NAS) device is a server that is dedicated to file sharing. NAS does not provide any of the activities that a server in a server-centric system typically provides, such as e-mail, authentication or file management. NAS allows more hard disk storage space to be added to a network that already utilizes servers without shutting them down for maintenance and upgrades. With a NAS device, storage is not an integral part of the server. Instead, in this storage-centric design, the server still handles all of the processing of data but a NAS device delivers the data to the user. A NAS device does not need to be located within the server but can exist anywhere in a LAN and can be made up of multiple networked NAS devices.

Fibre channel – A serial data transfer architecture developed by a consortium of computer and mass storage device manufacturers.

FC was designed for new mass storage devices and other peripheral devices that require very high bandwidth. Using optical fibre to connect devices, FC supports full-duplex data transfer rates of 100MBps. FC is compatible with, and is expected to eventually replace, SCSI for high-performance storage systems.

RAID – Short for Redundant Array of Independent (or Inexpensive) Disks, a category of disk drives that employ two or more drives in combination for fault tolerance and performance. RAID disk drives are used frequently on servers but aren't generally necessary for personal computers.

CPU – Abbreviation of central processing unit, and pronounced as separate letters. The CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

TCO - Abbreviation of Total Cost of Ownership, a very popular buzzword representing how much it actually costs to own a PC. The TCO includes:

Most estimates place the TCO at about 3 to 4 times the actual purchase cost of the PC. The TCO has become a rallying cry for companies supporting network computers. They claim that not only are network computers less expensive to purchase, but the TCO is also much less because network computers can be centrally administered and upgraded. Backers of conventional PCs, especially Microsoft and Intel, have countered with Zero Administration for Windows (ZAW), which they claim will also significantly reduce TCO.

SATA – Often abbreviated SATA or S-ATA, an evolution of the Parallel ATA physical storage interface. Serial ATA is a serial link -- a single cable with a minimum of four wires creates a point-to-point connection between devices. Transfer rates for Serial ATA begin at 150 MBps and SATA II 300MBps. One of the main design advantages of Serial ATA is that the thinner serial cables facilitate more efficient airflow inside a form factor and also allow for smaller chassis designs. In contrast, IDE cables used in parallel ATA systems are bulkier than Serial ATA cables and can only extend to 40cm long, while Serial ATA cables can extend up to one meter.

Serial ATA supports all ATA and ATAPI devices .

IPsec - Short for IP Security, a set of protocols developed by the Internet Engineering Task Force (IETF) to support secure exchange of packets at the IP layer. IPsec has been deployed widely to implement Virtual Private Networks (VPNs).

IPsec supports two encryption modes: Transport and Tunnel. Transport mode encrypts only the data portion (payload) of each packet, but leaves the header untouched. The more secure Tunnel mode encrypts both the header and the payload. On the receiving side, an IPsec-compliant device decrypts each packet.

For IPsec to work, the sending and receiving devices must share a public key. This is accomplished through a protocol known as Internet Security Association and Key Management Protocol/Oakley (ISAKMP/Oakley), which allows the receiver to obtain a public key and authenticate the sender using digital certificates.

IP SAN - A storage area network where all connected storage components are IP based. The IP SAN can be dedicated using Gigabit network switches or you can run over the existing LAN.

IP Storage - All IP storage is given a unique IQN name and an IP address. Clients/Servers connect to the IP storage using these names.

IQN Name - (iSCSI qualified name)—Based on reverse Domain Name System (DNS) naming conventions. Up to 255 characters, IQN names look like "iqn.year-mo.reverse FQDN" where FQDN is the fully qualified domain name. An example might be iqn.2003-05.com.microsoft.windows.myserver. (The IQN format has other variants as well, omitted here for the sake of brevity.)

EUI - (extended unique identifier)—Same as FC World-Wide Names. These names are formed by the eui. prefix followed by the 16-character (hexadecimal) name (24 bits for company name, assigned by the IEEE; 40 bits for a unique ID such as a serial number).

TCP/IP - Abbreviation of Transmission Control Protocol, and pronounced as separate letters. TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent.

Gigabit - When used to describe data transfer rates, it refers to 10 to the 9th power (1,000,000,000) bits.

Gigabit is abbreviated Gb, as opposed to gigabyte, which is abbreviated GB.

DAS – Direct Attach Storage is a method for connecting data storage devices to computers directly.

TOE – Short for TCP Offload Engine, processes the iSCSI commands on a dedicated chip on the controller, rather than use CPU cycles from the processor.

Open System – An Open System is a solution that is non proprietary.

TIED – Is a term that locks in the customer to a specified vendor that is not open and therefore does not benefit from the economies of scale that an Open System solution would.