ODS-5 is being introduced primarily to provide enhanced file
sharing capabilities for users of Advanced Server for OpenVMS 7.2
(formerly known as PATHWORKS for OpenVMS), as well as DCOM and
JAVA applications.
System managers must understand the impact of an ODS-5
environment before enabling it for general users. It is essential
that system managers perform the following steps before enabling
ODS-5:
o Review all ODS-5 restrictions.
o Understand the support levels for different OpenVMS
applications.
o Segregate applications that do not support ODS-5 or have not
been tested with ODS-5 names or volumes.
NOTE
It is recommended that you enable ODS-5 disks in a
homogeneous OpenVMS Version 7.2 (and later) Alpha cluster
only.
1 – Mixed-Version Support
Users on OpenVMS Alpha Version 7.2 (and later) systems can
take advantage of Extended File Specifications capabilities. In
contrast, systems running prior versions of OpenVMS cannot mount
ODS-5 volumes, correctly handle extended file names, or even see
extended file names.
The following topics describe support on OpenVMS Version 7.2
(and later) and on prior versions of OpenVMS in a mixed-version
cluster.
Users on OpenVMS Alpha Version 7.2 (and later) Systems
Users on OpenVMS Alpha Version 7.2 and later systems can continue
to access pre-Version 7.2 files and directories; for example,
they can do all of the following:
o Create and access deep directory structures on ODS-2 volumes.
o Read a BACKUP saveset created on an earlier version of
OpenVMS.
o Use DECnet to copy a file with an ODS-5 name to a file with an
ODS-2 name on a system running an earlier version of OpenVMS.
Users on pre-Version 7.2 Systems
On mixed-version clusters, some restrictions exist. Users on a
version of OpenVMS prior to Version 7.2:
o Cannot access any files on an ODS-5 volume. This is true
regardless of whether the volume is connected physically on
a CI or SCSI bus, or by an MSCP or QIO server.
o Cannot successfully create or restore an ODS-5 image saveset.
However, these users can successfully restore ODS-2-compliant
file names from an ODS-5 saveset.
2 – Mixed-Architecture Support
All Extended File Specifications capabilities are available on
OpenVMS Alpha Version 7.2 and later systems. Current ODS-2 volume
and file management functions remain the same on both VAX and
Alpha Version 7.2 (and later) systems; however, extended file
naming and parsing are not available on VAX systems.
The following topics describe support on OpenVMS VAX and Alpha
systems in a mixed-architecture cluster.
Limited Extended File Specifications Capabilities on VAX Systems
In mixed-architecture OpenVMS Version 7.2 (and later) clusters,
the following Extended File Specifications capabilities are
available on OpenVMS Version 7.2 (and later) VAX systems:
o Ability to mount an ODS-5 volume
o Ability to write and manage ODS-2-compliant files on an ODS-5
volume
o See only \pISO_LATIN\.??? or \pUNICODE\.??? when accessing an
ODS-5 file specification
BACKUP Limitations
In a mixed architecture cluster, users cannot successfully create
or restore an ODS-5 image saveset. However, these users can
successfully restore ODS-2-compliant file names from an ODS-5
saveset.
3 – Network Support
Although Extended File Specifications is intended to provide
enhanced file naming capabilities to Advanced Server for OpenVMS
7.2 Version 7.2 for OpenVMS Version 7.2, network access with
ODS-5 volumes and extended file names is currently being tested.
The length of an extended file specification that can be passed
over the network using DECnet is restricted to a maximum of 255
bytes.
4 – Application Support
OpenVMS applications should be evaluated and tested to determine
whether they function correctly when Extended File Specifications
is enabled. The OpenVMS System Manager's Manual, Volume 1:
Essentials contains guidelines for evaluating applications, and
the Guide to OpenVMS File Applications contains details about the
technical aspects of Extended File Specifications that can affect
the behavior of an application.
5 – User Support
When you enable ODS-5 volumes on an OpenVMS cluster, you should
make users aware of the following characteristics:
o Extended file names caooonot be used on ODS-2 volumes.
o Case is determined by the first instance of an extended file
name.
o There are special rules for case preservation and case
blindness when using extended file names.
o Some system utilities and DCL commands have a /STYLE qualifier
to control the display of file names.
o Error messages can vary when different parse style are used.
o Extended file names are not visible from a VAX system.
The OpenVMS System Manager's Manual, Volume 1: Essentials
contains information for setting user's expectations of Extended
File Specifications.