Glossary G-H

G-J

G_Port

A port on a FC switch designed to function as an F_Port or an E_Port that connects both nodes. This can be external to FC switches through interswitch links (ISLs), and SCSI-to-FC bridges/routers. This type of universal port is becoming increasingly popular in developing simpler port utilization structures. These ports are vendor-dependent on implementation.

Head and Disk Assembly (HDA)

The mechanical assembly that houses the read and write heads for a magnetic disk. The assembly moves mechanically over the spinning platters of the media as it performs its operations. Additional functionality has been moved into the HAD to facilitate greater read/write performance.

InfiniBand

An I/O standard that provides a switched fabric network replacing the traditional bus networks of computers. The InfiniBand standard requires that all I/O be connected through an InfiniBand switch with the added benefit that connecting computers together makes clustering a more scalable and efficient process.

iSCSI

A new I/O standard that provides for the execution of a SCSI- based I/O operation over a TCP/IP network. This allows a server to execute a block I/O operation to a remote storage device. The new standard provides additional specifications for encapsulating SCSI-based commands into TCP communications and transferring them through an IP packet to corresponding SCSI-based storage devices that are IP addressable and have compatible TCP processing capabilities. Initial implementations have required new NIC cards to support these functions at both the server and storage device level.

JBOD

Defined as 'just a bunch of disks,' this term defines a storage array in which all devices within the array are addressable independent units. These provide additional capacity but do not offer any fault resiliency in the event of an inoperable drive. Partitioning data throughout the disks and providing a layer of virtualization services is generally part of the I/O management of the operating system. These functions are also available through third-party software applications.