From: John, dtn 381-0378 24-May-1996 1721 (
Date: Fri May 24 1996 - 16:31:10 CDT

TruCluster Software V1.0 for Digital UNIX


* Supports PCI to Memory Channel, a high-performance interconnect with a
   three-to-five microsecond latency

* Supports database applications, such as Oracle Parallel Server (OPS)

* Distributed Lock Manager (DLM) provides synchronized access to shared

* Distributed Raw Disk (DRD) supports applications by presenting a
   cluster-wide view of disks accessed using a character or raw device


TruCluster Software V1.0 for Digital UNIX combines the advantages of
symmetric multiprocessing (SMP), distributed computing, and fault
resilience to achieve scalability, high availability, centralized cluster
management, and high performance. By operating over the PCI to Memory
Channel interconnect, TruCluster provides direct memory connections
between cluster systems, reduces system overhead, and provides a
significant improvement in message latency. TruCluster Software supports

* Oracle Parallel Server (OPS)
* Distributed lock manager (DLM)
* Shared disk access
* Configuration and cluster membership management
* DECsafe Available Server Software V1.3
* Cluster monitor

These components are necessary for a distributed database system to
synchronize, access data, and respond to failures or to changes in
configurations. Availability services included in the TruCluster Software
product are provided with Digital's DECsafe Available Server software.
(See the "DECsafe Available Server Software V1.3 for Digital UNIX"
article in this issue of Customer Update.) The technology allows for
automatic process restart upon host failures. The cluster provides
multi-host access to SCSI disks and a generic failover mechanism for
disks and applications. Within a cluster, the administrator can set up
reconfiguration services that make disks and applications highly
available to client systems.

The Distributed Lock Manager (DLM) and shared disk access are at the core
of the database system. DLM provides the distributed synchronization that
makes shared access possible and supports other applications. Memory
Channel and DLM are integrated with cluster configuration management
through the Connection Manager via low level Memory Channel cluster
configuration code. These components work together to provide
synchronized access to the database in the presence of failures.

Distributed Raw Disk (DRD) for TruCluster Software supports database
applications by presenting a cluster-wide view of disks using the raw
device interface. DRD also provides a DRD name space and access mechanism
for both physical and logical volumes. DRD devices are accessible from
any cluster member using the DRD device name. Applications use the
cluster lock manager to serialize concurrent access to DRD device data.
The Connection Manager subsystem maintains information about the cluster
membership. In addition, it establishes and maintains a high-performance,
reliable communications path between each cluster member. TruCluster
Software also features a cluster monitor; a graphical view of the cluster
configuration that can be used to determine the current state of
availability and connectivity in the cluster.

TruCluster Software supports a variety of hardware configurations that
are cost-effective and meet demanding performance and data availability
criteria. Other configurations use multiple SCSI buses and dual Memory
Channel interfaces to eliminate any single point of failure.

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