Installing Hardware Options
VAX 4000 Model 108 User Information 3–23
A DSSI device has a built-in DSSI VAXcluster capability that can dynamically serve two
or more systems. DSSI adapters, embedded in the system CPU, let you extend a DSSI bus
by connecting it to another system.
Using an external DSSI cable, DSSI-based systems can be connected to form a DSSI
VAXcluster configuration.
The benefits of a DSSI VAXcluster configuration are:
•
VAXcluster features such as shared data across systems and satellite nodes are
available to you.
•
Higher system availability --- If one of the systems is unavailable due to a system
malfunction, the satellites booted through it can continue operating through the other
system.
If one system fails, all satellite nodes booted through that system lose connections to the
system disk. Each satellite knows that the system disk is available through a second path.
The satellite nodes establish a new connection through the other system and continue
operation.
To increase system availability, a second system disk can be added to each boot node. If
one system disk fails, the other system disk continues to serve one system and the satellite
nodes booted through it. As in any VAXcluster, a second system disk improves availability
but increases system management tasks.
Figure 2-21 shows how to attach a DSSI cable to a DSSI port on a VAX 4000 Model 108
system. DSSI cables may be attached to either of the DSSI ports in the same way. Figure
3-14 shows a typical DSSI connection between a VAX 4000 Model 108 system’s TriLink
connector and another VAX 4000 system.
DSSI terminators must be used on all TriLink connectors not connected to DSSI devices.
