Guidelines for OpenVMS Cluster Configurations
D.4 Managing OpenVMS Cluster Systems Across Multiple Sites
In general, you manage a multiple-site OpenVMS Cluster using the same
tools and techniques that you would use for any OpenVMS Cluster
interconnected by a LAN. The following sections describe some
additional considerations and recommends some system management tools
and techniques.
The following table lists system management considerations specific to
multiple-site OpenVMS Cluster systems.
| Problem |
Possible Solution |
Multiple-site configurations present an increased probability of the
following failure modes:
- OpenVMS Cluster quorum loss resulting from site-to-site
communication link failure.
- Site loss resulting from power failure or other breakdown can
affect all systems at that site.
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Assign votes so that one preferred site has sufficient votes to
maintain quorum and to continue operation if the site-to-site
communication link fails or if the other site is unavailable. Select
the site with the most critical applications as the primary site. Sites
with a few noncritical systems or satellites probably should not have
sufficient votes to continue.
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Users expect that the local resources will either continue to be
available or will rapidly become available after such a failure. This
might not always be the case.
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Consider the following options for setting user expectations:
- Set management and user expectations regarding the likely effects
of failures, and consider training remote users in the procedures to be
followed at a remote site when the system becomes unresponsive because
of quorum loss or other problems.
- Develop management policies and procedures for what actions will be
taken to identify and handle these failure modes. These procedures may
include manually adjusting quorum to allow a site to continue.
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D.4.1 Methods and Tools
You can use the following system management methods and tools to manage
both remote and local nodes:
- There are two options for remote-site console access when you use
an intersite link through a DECserver in reverse LAT mode.
- Use the following tools to connect remote consoles:
- SET HOST/LAT command
- POLYCENTER Console Manager
- OpenVMS Cluster Console System (VCS)
- Disaster Tolerant Cluster Services for OpenVMS, a Compaq system
management and software package
- Use a modem to dial up the remote system consoles.
- An alternative to remote-site console access is to have a system
manager at each site.
- To enable device and processor control commands to take effect
across all nodes in an OpenVMS Cluster system, use the System
Management utility (SYSMAN) that is supplied with the OpenVMS operating
system.
D.4.2 Shadowing Data
Volume Shadowing for OpenVMS allows you to shadow data volumes across
multiple sites. System disks can be members of a volume shadowing or
RAID set within a site; however, use caution when configuring system
disk shadow set members in multiple sites. This is because it may be
necessary to boot off a remote system disk shadow set member after a
failure. If your system does not support FDDI booting, it will not be
possible to do this.
See the Software Product Descriptions (SPDs) for complete and
up-to-date details about Volume Shadowing for OpenVMS (SPD
27.29.xx) and StorageWorks RAID for OpenVMS (SPD
46.49.xx).
D.4.3 Monitoring Performance
Monitor performance for multiple-site OpenVMS Cluster systems as
follows:
- Monitor the virtual circuit (VC) packet-loss count and round-trip
time values using the System Dump Analyzer (SDA). The procedures for
doing this are documented in OpenVMS Cluster Systems.
- Monitor the intersite link bit error ratio (BER) and packet loss
using network management tools. You can use tools such as POLYCENTER
NetView or DECmcc to access the GIGAswitch and WAN T3/SONET option
card's management information and to set alarm thresholds. See the
GIGAswitch, WAN T3/SONET card, POLYCENTER, and DECmcc documentation, as
appropriate.
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