Since OpenVMS Alpha Version 7.2, it has been possible to run
a single-instance Galaxy on any Alpha platform except for the ES45. This
capability allows early adopters to evaluate OpenVMS Galaxy features and,
most important, to develop and test Galaxy-aware applications without
incurring the expense of setting up a full-scale Galaxy computing
environment on a system capable of running multiple instances of OpenVMS
(for example, an AlphaServer 8400).
A single-instance Galaxy running on an Alpha system is not
an emulator. It is OpenVMS Galaxy code with Galaxy interfaces and
underlying operating system functions. All Galaxy APIs are present
in a single-instance Galaxy (for example, resource management, shared
memory access, event notification, locking for synchronization,
and shared memory for global sections).
Any application that is run on a single-instance Galaxy exercises
the identical operating system code on a multiple-instance Galaxy
system. This is accomplished by creating the configuration file SYS$SYSTEM:GLX$GCT.BIN,
which OpenVMS reads into memory. On a Galaxy platform (for example,
an AlphaServer 8400), the console places configuration data in memory
for OpenVMS to use. Once the configuration data is in memory, regardless
of its origin, OpenVMS boots as a Galaxy instance.