Specifications
OpenVMS Operating System for Alpha and VAX (Versions 7.1, 7.1–1H1, 7.1–1H2, and 7.1–2) SPD 41.87.06
OpenVMS supports the standards defined by the ATM
Forum’s LANE Version 1.0 specifications for LAN emu-
lation over an ATM network. By implementing an emu-
lated LAN over an ATM network, you enable a group of
ATM stations to act like a traditional LAN. LAN emulated
over an ATM network allows you to run your existing ap-
plications basically unchanged, while the computers on
which your applications are running are connected to
the ATM network.
OpenVMS implements the standards defined in RFC
1577 (Classical IP over ATM). This implementation in-
troduces the necessary system interface for Classical
IP (CLIP) over an ATM network, and enables CLIP and
ARP protocols in an ATM network environment to be
configured as a logical IP subnetwork (LIS). Consult
your IP product documentation for the status of support
of IP over this interface.
DECnet-Plus offers task-to-task communications, file
management, downline system and task loading, net-
work command terminals, and network resource shar-
ing capabilities as defined in the Digital Network Archi-
tecture (DNA) Phase V protocols. DECnet-Plus pro-
vides the newest DECnet features such as extended
addressing and downline-load performance enhance-
ments. DECnet-Plus integrates DECnet and OSI pro-
tocols and now provides a linkage to TCP/IP using Re-
quest for Comments (RFC) 1006 and RFC 1859. DEC-
net and OSI applications can now be run over DECnet
(NSP), OSI (CLNS), and TCP/IP transports.
DECnet for OpenVMS VAX and Alpha offers the net-
working capabilities as defined in the Digital Network
Architecture (DNA) Phase IV. For more information, re-
fer to the DECnet-Plus and DECnet Software portion of
the Associated Products section of this SPD.
Terminal Server Products
Compaq’s terminal server products provide terminal
server access to OpenVMS. When used in an Open-
VMS Cluster environment, terminal servers distribute
users across the available Alpha and VAX systems at
login time.
OpenVMS can also establish a connection to other de-
vices (such as printers) that are attached to such termi-
nal servers.
Reliability
OpenVMS handles hardware errors as transparently as
possible while maintaining data integrity and providing
sufficient information to diagnose errors. The system
limits the effects of an error by first determining if the
error is fatal. If the error occurs in system context, the
current OpenVMS system shuts down. If the error is not
fatal, the system recovers actions pertinent to the error
and continues the current operation.
In all cases, information relevant to the error is written
to the error log file for later analysis. Hardware errors
include the following categories:
• Processor errors. These include processor soft
errors, processor hard errors, processor machine
checks, and adapter errors.
• Memory errors. These can be unrecoverable (hard)
errors or recoverable (soft) errors. The system ex-
amines memory at startup time and does not use
any bad pages. During system operation, the sys-
tem corrects all single-bit memory errors for those
systems with error correction code (ECC) memory.
On OpenVMS VAX, an unrecoverable error causes
the memory page on which the error occurred to be
added to the bad page list. If the page has not
been modified, system operation continues with a
new copy of the page.
• Correctable memory errors. A primary cause of
these correctable memory errors is Alpha particle
radiation. On some processors, when correctable
memory errors occur, the memory controller corrects
only the data returned to the CPU or I/O controller.
The actual data in memory is left with the error intact.
Subsequent read operations cause correction cycles
to occur and, in most cases, an interrupt to report
the error. On many of these processors, OpenVMS
monitors the occurrence of correctable memory er-
rors and, in almost all cases, is able to remove the er-
ror condition by rewriting the data in memory. Rewrit-
ing the data causes the data to be corrected in that
memory location. On OpenVMS VAX, if the cause
of the error is not transient, and the error condition
persists, the operating system attempts to move the
data from the existing page, which contains the error,
to a new page. The original page is then retired from
use.
Other failures include:
• Operating system errors (system-detected inconsis-
tencies or architectural errors in system context)
• User errors
• I/O errors
The system logs all processor errors, all operating
system errors detected through internal consistency
checks, all double-bit memory errors (and a summary
of corrected single-bit memory errors), and most I/O er-
rors.
If the system is shut down because of an unrecoverable
hardware or software error, a dump of physical mem-
ory is written. The dump includes the contents of the
processor registers. The OpenVMS System Dump An-
alyzer (SDA) utility is provided for analyzing memory
dumps.
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