System Features; Installation And Maintenance; Clustering; Pci To Memory Channel Interconnect - Compaq DS20E - AlphaStation - 1 GB RAM Technical Manual

System Features

Auto reboot. On systems running Tru64 UNIX or OpenVMS, a
firmware environment variable lets you set the default action
the system takes on power-up, reset, or after an operating
system crash. For maximum system availability, the variable
can be set to cause the system to automatically reboot the
operating system after most system failures.
Software installation. The operating systems are factory
installed. Factory installed software (FIS) allows you to boot
and use your system in a shorter time than if you install the
software from a distribution kit.
Diagnostics. During the power-up process, diagnostics are run
to achieve several goals:
Provide a robust hardware platform for the operating
system by ensuring that any faulty hardware does not
participate in the operating system session. This maxi-
mizes system uptime by reducing the risk of system
failure.
Enable efficient, timely repair.
The system has a built-in firmware update utility (LFU) that
provides update capability for console and PCI I/O adapter
firmware. A fail-safe loader provides a means of reloading the
console in the event of corrupted firmware.
Thermal management. The air temperature and fan operation
are monitored to protect against overheating and possible
hardware destruction. Two fans in the rear of the enclosure
cool the system box; if one system fan fails, the second one
speeds up to provide additional cooling. Also, each power
supply has two fans, and each processor has its own fan on the
chip heatsink. The system shuts down if a processor fan fails
or if the temperature reaches a threshold. The system fans are
hot swappable.
Error handling. Parity and other error conditions are detected
on the PCI and ISA buses. The memory checking scheme
corrects single-bit errors and detects double-bit errors.
Multiple ECC corrections to single-bit errors detected by the
operating systems help in determining where in the system the
error originated. Errors are logged for failure analysis.
Disk hot swap. The hardware is designed to enable hot swap
of disks. Hot swap is the removal of a disk or disks from any
of the storage compartments while the rest of the system
remains powered on and continues to operate. This feature
contributes significantly to system availability. Since many
disk problems can be fixed without shutting down the entire
system, users lose access only to the disks that are removed.
N+1 power redundancy A third power supply can be added to
provide redundant power to the system box.
An external UPS can be used to support critical customer con-
figurations. Because power is maintained for the entire system
(CPU, memory, and I/O), power interruptions are completely
transparent to users.
8

Installation and Maintenance

The systems are designed for easy hardware, software, and
option installation. Options ordered with a system are
preinstalled and tested at the factory. The operating systems
are also installed at the factory. Installation of the system is
relatively simple and may take only 30 minutes.
Some maintenance tasks can be performed while the system is
running. Systems are designed so that system fans, power
supplies, and disks can be replaced without shutting down the
system.

Clustering

A cluster is a loosely coupled set of systems that behaves (is
addressed and managed) like a single system, but provides
high levels of availability through redundant CPUs, storage,
and data paths. Clusters are also highly scalable; that is, CPU,
I/O, storage, and application resources can be added incre-
mentally to efficiently increase capacity. For customers, this
translates to reliable access to system resources and data, and
investment protection of both hardware and software.
Clustering allows multiple computer systems to communicate
over a common interface, share disks, and spread the comput-
ing load across multiple CPUs.

PCI to Memory Channel Interconnect

Under Tru64 UNIX and OpenVMS, you can build high-avail-
ability clusters using the PCI to Memory Channel interconnect.
The Memory Channel interconnect is a high-bandwidth, low-
latency PCI-based communications interconnect for up to eight
AlphaServer systems. Data written to one computer's memory
is shared by other computers on the Memory Channel bus.
The PCI CCMAB adapter is the interface between a PCI and a
Memory Channel bus. This bus is a memory-to-memory
computer system interconnect that permits I/O space writes in
one computing node to be replicated into the memories of all
other nodes on the Memory Channel bus. A write performed
by any CPU to its reflected address region results in automatic
hardware updates to memory regions in other nodes. One
node's write is "reflected" to other nodes as a direct side effect
of the local write. This provides a memory region with
properties similar to a high-performance shared memory
across a group of nodes.

Operating System Support

For clustered Tru64 UNIX systems, TruCluster Software
solutions allow users access to network services and provide
further failover recovery from server, network, or I/O failures.
Tru64 UNIX cluster systems use the SCSI bus and/or PCI to
Memory Channel interconnect bus between disks and systems.
OpenVMS cluster systems use the CI, SCSI, Ethernet, FDDI,
DSSI, and Memory Channel as the interconnect between disks
and systems.