Extended File Specifications includes support for the following:
o The ODS-5 disk structure. ODS-5 is an extension to the
existing ODS-2 disk structure, and adds the ability to use
extended file names that can be more easily mapped between
Windows and OpenVMS. ODS-5 expands the available character
set and filename length to be consistent with Windows 95 and
Windows NT, and sets the stage for future Unicode file name
support through PATHWORKS.
o Deeper directories. Enhancements to RMS provide deep directory
support on both ODS-2 and ODS-5 volumes.
Taken together, these components provide much greater flexibility
for OpenVMS Alpha systems (using Advanced Server for OpenVMS
7.2, formerly known as PATHWORKS for OpenVMS), to store, manage,
serve, and access files that have names similar to those in a
Windows 95 or Windows NT environment.
This topic provides an overview of the benefits, features,
and support for Extended File Specifications, as well as
changes in OpenVMS behavior that occur when using Extended File
Specifications.
1 – Benefits
The deep directories and extended file names supported by
Extended File Specifications provide the following benefits:
o OpenVMS system managers can manage files with extended names
and deep directories in the same manner as Windows NT users.
o Users of Advanced Server for OpenVMS 7.2 (formerly known as
PATHWORKS for OpenVMS) have the ability to store longer file
names and use deeper directory structures, which are more
compatible with Windows 95 and Windows NT file names.
o Applications developers who are porting applications from
other environments that have support for deep directories can
use a parallel structure on OpenVMS.
o Longer file naming capabilities and Unicode support enables
OpenVMS Alpha Version 7.2 and later to act as a DCOM server
for Windows NT clients, and ODS-5 provides capabilites that
make the OpenVMS and Windows NT environment more homogeneous
for DCOM developers.
o JAVA applications on OpenVMS will comply with JAVA object
naming standards.
o General OpenVMS users can make use of long file names, new
character support, and the ability to have lowercase and
mixed-case file names.
2 – Features
Extended File Specifications consists of two main features, the
ODS-5 volume structure, and support for deep directories.
2.1 – ODS-5
OpenVMS Alpha Version 7.2 and later implements On-Disk Structure
Level 5 (ODS-5). This structure provides the basis for creating
and storing files with extended file names. You can choose
whether or not to enable ODS-5 volumes on your OpenVMS Alpha
systems.
The ODS-5 volume structure allows the following features:
o Long file names
o More characters legal within file names
o Preservation of case within file names
2.2 – Deep Directories
Both ODS-2 and ODS-5 volume structures support deep nesting of
directories, subject to the following limits:
o There can be up to 255 levels of directories.
o The name of each directory can be up to 236 8-bit or 117
16-bit characters long.
Complete file specifications longer than 255 bytes are
abbreviated by RMS when presented to unmodified applications.
For example, a user can create the following deeply nested
directory:
$ CREATE/DIRECTORY [.a.b.c.d.e.f.g.h.i.j.k.l.m]
A user can create the following directory with a long name on an
ODS-5 volume:
$ CREATE/DIRECTORY
[.AVeryLongDirectoryNameWhichHasNothingToDoWithAnythingInParticular]
2.2.1 – Directory Naming Syntax
On an ODS-5 volume, directory names conform to most of the same
conventions as file names when using the ISO Latin-1 character
set. Periods and special characters can be present in the
directory name, but in some cases, they must be preceded by a
circumflex (^) in order to be recognized as literal characters.
3 – Considerations
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.
3.1 – 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.
3.2 – 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.
3.3 – 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.
3.4 – 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.
3.5 – 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.
4 – Impact
The main goal of Extended File Specifications is to provide
extended file naming capabilities, while also:
o Maintaining high reliability, scalability, and availability
o Maintaining the traditional (ODS-2) serial file interoperation
capabilities
o Causing the least possible amount of change for layered
products and applications
However, once ODS-5 volumes are enabled, some of the new
capabilities can potentially impact certain applications or
layered products, as well as some areas of system management.
The following guidelines and description of changes in the base
operating system will help you determine the level of impact on
your OpenVMS environment.
4.1 – Support Guidelines
Under Extended File Specifications, existing applications and
layered products that are coded to documented interfaces, as well
as most DCL command procedures, should continue to work without
modification.
However, applications that are coded to undocumented interfaces,
or include any of the following, may need to be modified in order
to function as expected on an ODS-5 volume:
o Internal knowledge of the file system, including knowledge
of:
The data layout on disk
The contents of file headers
The contents of directory files
o File parsing tailored to a particular on-disk structure.
o Assumptions about the syntax of file specifications, such as
the placement of delimiters and legal characters.
o Assumptions about the case of file specifications. Mixed
and lowercase file specifications will not be converted to
uppercase, which can affect string matching operations.
o Assumptions that file specifications are identical between RMS
and the file system.
NOTE
All unmodified XQP applications running on an OpenVMS
VAX or Alpha system that access an ODS-5 volume will see
pseudonames returned in place of Unicode or ISO Latin-
1 names that are not ODS-2 compliant. This can cause
applications to act in an unpredictable manner.
Applications that specify or retrieve filenames with the
XQP interface using ODS-5 disks must be modified in order to
access files with extended names.
4.2 – RMS Changes
To support Extended File Specifications, the Record Management
Services (RMS) have been enhanced to provide the following
functions through existing interfaces:
o Support for a wider range of characters in a file name,
extension, and directory
o Access to file specifications with extended characters
o Support for directory structures deeper than eight levels
o Access to file specifications longer than 255 bytes through
the NAM block with some restrictions in functionality
o Access and complete specification of file specifications
longer than 255 bytes by callers who are aware of the new
naming characteristics through a new interface (NAML block)
4.2.1 – Extended File Names
With ODS-5 enabled, RMS can manipulate filenames and subdirectory
specifications of up to 255 8-bit or 16-bit characters in length.
RMS can handle a total path name 512 8-bit or 16-bit characters
in length.
Prior to OpenVMS Alpha Version 7.2, the NAM block interface could
pass file specifications of up to 255 bytes each (including the
resultant file specification). The following topics describe the
changes that allow for passing longer file specifications and
that provide compatibility with applications using the NAM block
interface prior to this release.
4.2.2 – Additional Character Sets
With ODS-5, RMS supports access to files and directories whose
names contain arbitrary 8-bit characters, except for the C0
control set (hex 00 through 1F) and the following characters:
Double quotation marks (")
Asterisk (*)
Backslash (\)
Colon (:)
Left and right angle brackets (< >)
Slash (/)
Question mark (?)
Vertical bar (|)
Note that this explicitly includes both the C1 character set (hex
80-9F) as well as graphical and other characters between 9F and
FF. This allows the entire ISO Latin-1 character set (with the
7-bit character exclusions noted above) and any defined Unicode
character.
4.2.3 – Deeply Nested Directories
Under Extended File Specifications on Alpha, RMS supports deep
nesting of up to 255 directories, with the restriction that the
total directory specification must be no longer than 512 8-bit
or 16-bit characters. The deep nesting of directories is also
supported on ODS-2 disks.
4.3 – File System (XQP) Changes
The following Files-11 Extended QIO Processor (XQP) file system
enhancements are offered under Extended File Specifications
through the $QIO interface. Note that in some cases, XQP file
format rules may differ from those that apply to other system
services that accept file names, such as those provided by RMS.
o The current restrictions on the format and content of file
names have been modified, specifically:
- The 39.39 file name length restriction was removed to allow
longer file names, up to 236 8-bit characters or 117 16-bit
characters
- The use of characters from the ISO Latin-1 multinational
character set is supported in file specifications
- Support for the entry and storage of file and directory
specifications in Unicode.
4.4 – DCL Commands and Utilities
In DCL commands, you can select either of the following styles
for parsing file specifications:
o Traditional filenames are allowed on both ODS-2 and ODS-5
volumes.
o Extended filenames are allowed on ODS-5 but not on ODS-2
volumes.
Some OpenVMS commands and utilities have new qualifiers to
control the interpretation and display of file specifications.
NOTE
DCL lexical functions use the DEC-Multinational character
set, which is different from the ISOLatin-1 character set
used for file names on an ODS-5 disk. This can lead to
unexpected results if, for example, you use the DCL function
F$EDIT to upcase a filename.
Some DCL commands and OpenVMS utilities have been specifically
modified to take advantage of all the features of extended file
names. These utilities and commands accept and handle extended
file specifications without error and without modifying their
expected case.
Other DCL commands and OpenVMS utilities have had little or
no modification to take advantage of extended file names.
These utilities and commands are expected to handle most of
the attributes of extended file specifications (such as new
characters and deep directory structures) correctly.
Extended File Specifications Support fully defines the different
levels of support for extended file names provided by DCL
commands and OpenVMS utilities in OpenVMS Version 7.2 and later.
The following DCL commands and OpenVMS utilities provide full
support for extended file names:
ANALYZE /AUDIT
ANALYZE /DISK
ANALYZE /RMS
BACKUP
CONVERT
CONVERT /RECLAIM
COPY
CREATE /DIRECTORY
DELETE
DIRECTORY
DUMP
EDIT /ACL
EXCHANGE /NETWORK
FDL
PURGE
RECOVER/RMS
RENAME
SEARCH
SET SECURITY
SYSMAN
TYPE
The following table lists the new features in DCL to support
Extended File Specifications.
DCL Command New Features
COPY Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
DELETE Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
DIRECTORY Added the following items:
o Qualifier, /STYLE, with new keywords,
EXPANDED and CONDENSED
o Display item to /FULL to display Client
Attributes
DUMP Added the following items:
o Display item to /DIRECTORY to display
Name type attribute
o Display item to /HEADER to display new
attributes
o Qualifier, /STYLE, with new keywords,
EXPANDED and CONDENSED
EXCHANGE NETWORK Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
F$FILE_ATTRIBUTES Added new item codes: FILE_LENGTH_HINT,
Lexical VERLIMIT, DIRECTORY
F$GETDVI Lexical Added new type to the ACPTYPE item code.
F$GETJPI Lexical Added new item codes: PARSE_STYLE_PERM and
PARSE_STYLE_IMAGE
INITIALIZE Added a new qualifier: /STRUCTURE=5
device-name[:] volume-label
PRINT Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
PURGE Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
RENAME Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SEARCH Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SET ACL Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SET DEFAULT Updated the following items:
o Modified the directory-spec parameter
to accept ODS-5-compliant file
specifications.
SET DIRECTORY Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SET FILE Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SET PROCESS Added a new qualifier: /PARSE_
STYLE=(keyword), where keywords are
TRADITIONAL and EXTENDED.
SET SECURITY Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
SET VOLUME Added a new qualifier: /STRUCTURE_LEVEL=5
SHOW DEVICE/FULL Updated the display information to show
the disk structure level.
SUBMIT Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
TYPE Added new qualifier, /STYLE, with new
keywords, EXPANDED and CONDENSED
For detailed information about the enhancements made to the
OpenVMS operating system and utilities in support of Extended
File Specifications, see the OpenVMS DCL Dictionary: A-M, the
OpenVMS DCL Dictionary: N-Z, and the OpenVMS Utility Routines
Manual.
4.5 – DCL Command Parameters
Command procedures that use file names as parameters can produce
different results in an ODS-5 environment.
See DCL Command Parameters for more information about using ODS-5
style names in DCL command procedures.
4.6 – System Services Changes
The following system services have been modified or added to
support Extended File Specifications:
o New services:
- $SET_PROCESS_PROPERTIESW
- $CVT_FILENAME
o Changed services:
- $CREPRC
- $GETJPI
- $SETDDIR