Technical data

GL–8 Glossary
hot spots A portion of a disk drive frequently accessed by the host. Because the data
being accessed is concentrated in one area, rather than spread across an
array of disks providing parallel access, I/O performance is significantly
reduced. See also hot disks.
hot swap A method of device replacement that allows normal I/O activity on a
device’s bus to remain active during device removal and insertion. The
device being removed or inserted is the only device that cannot perform
operations during this process. See also cold swap and warm swap.
IBR Initial Boot Record.
ILF Illegal function.
INIT Initialize input and output.
initiator A SCSI device that requests an I/O process to be performed by another
SCSI device, namely, the SCSI target. The controller is the initiator on the
device bus. The host is the initiator on the host bus.
instance code A four-byte value displayed in most text error messages and issued by the
controller when a subsystem error occurs. The instance code indicates when
during software processing the error was detected.
interface A set of protocols used between components, such as cables, connectors,
and signal levels.
I/O Refers to input and output functions.
I/O driver The set of code in the kernel that handles the physical I/O to a device. This
is implemented as a fork process. Same as driver.
I/O interface See interface.
I/O module A 16-bit SBB shelf device that integrates the SBB shelf with either an 8-bit
single ended, 16-bit single-ended, or 16-bit differential SCSI bus.
I/O operation The process of requesting a transfer of data from a peripheral device to
memory (or visa versa), the actual transfer of the data, and the processing
and overlaying activity to make both of those happen.