Specifications

3–3
Compaq HSG80 Array Controller ACS Version 8.4 Configuration and CLI Reference Guide
Host Bus
When the host communicates to the controller through the host bus, the controller
maps that communication to the logical units on the device bus. Even though the
physical devices exist, the host accesses only the logical units that you have created
from making containers and storagesets. This way, the controller helps the host to be
more efficient by doing the following:
■ combines several devices into a storageset, which allows the host to spread its I/O
load across more devices.
■ assists with certain low-level I/O requests, which frees up the host for processing
more intensive applications.
Controller Device Bus
A controller communicates between the physical devices and the host, connecting to
the devices directly over one of the six available device I/O buses. The controller has
access to physical devices, whereas the host has access to only the logical units.
Table 3–1. Key to Figure 3–1 Host Bus and Controller Device SCSI Bus
Item Description
➀
Host
➁
Controller A
➂
Controller B
➃
Logical units made from storagesets
➄
Host bus
➅
Controller device bus