Document revision date: 15 July 2002

A system manager can help users become accustomed to Extended File Specifications by explaining the differences between ODS-2 and ODS-5 file names. These differences become most apparent when users change from ODS-2 to ODS-5 styles.

If you pass the following usage notes along, users might find them helpful. These notes are divided into the following categories:

• New Extended File Specifications characteristics
• ODS-2 and ODS-5 used together
• Architecture-related notes

The following notes discuss issues related to new Extended File Specifications characteristics that are unfamiliar to users.

Be Aware of Volume Structure

Make sure you know whether a disk is an ODS-2 or ODS-5 volume so that you can place ODS-5 files on ODS-5 volumes.

You can display the type of volume by entering commands similar to the following:

$ SHOW DEVICE DKA500:/FULL Disk AABOUT$DKA500:, device type DZ25 Disk, is online, allocated, deallocate on dismount, mounted, file-oriented device, shareable. Error count 0 Operations completed 155 . . . Volume Status: ODS-5, subject to mount verification, file high-water marking, write-back caching enabled. $ SHOW DEVICE DKA200:/FULL Disk AABOUT$DSA200:, device type RZ25 Disk, is online, allocated, deallocate on dismount, mounted, file-oriented device, shareable. Error count 0 Operations completed 232 . . . Volume Status: ODS-2, subject to mount verification, file high-water marking, write-back caching enabled.

After each command, the Volume Status: that is displayed indicates whether the volume is ODS-5 or ODS-2.

Do Not Use Extended File Names on ODS-2 Volumes

You cannot create a file with an ODS-5 extended file name on an ODS-2 volume.

In the following example, DKA200: is an ODS-2 volume, and the parse style is EXTENDED, which causes RMS to return an error message.

$ SET DEFAULT DKA200:[TEST] $ CREATE x.x.x.x %CREATE-E-OPENOUT, error opening DKA200:[TEST]X^.X^.X.X; as output -RMS-E-CRE, ACP file create failed -SYSTEM-W-BADFILEVER, bad file version number

Case Is Determined by the First Instance of an Extended File Name

On an ODS-5 volume, the case for all versions of a file name is identical; the case is preserved as the file name was first created.

In the following example, the disk is ODS-5.

$ SET DEFAULT DKA500:[TEST] $ SET PROCESS /PARSE_STYLE=EXTENDED $ CREATE myfile.txt [Ctrl/Z] $ CREATE MYFILE.TXT [Ctrl/Z] $ DIRECTORY Directory DKA500:[TEST] myfile.txt;2 myfile.txt;1

Be Aware of Case Preservation but Case Blindness of Extended File Specifications

Keep in mind that although an ODS-5 disk preserves the case of a file as it is first entered, it searches for files in a case-blind manner. Similarly, users must also be careful when they do comparisons, such as when they use DCL string functions like .EQS. and F$LOCATE in a DCL command procedure.

The following example demonstrates the importance of case-blind matching of file names in DCL. In the program, notice that you specify no argument to do a case-sensitive match but that you specify an argument to do a case-blind match.

This program uses F$SEARCH to find all the files that have a file type of .TXT. Because RMS (and therefore F$SEARCH as well does case-blind matching, F$SEARCH also finds files with the file type .txt. F$SEARCH then uses F$LOCATE to search the file name for TEST. Because F$LOCATE does case-sensitive comparisons, it fails to match unless you first change the string to uppercase.

$ case_blind = 0 $ if p1 .nes. "" then case_blind = 1 (1) $loop: $ file = f$search("*.TXT;") (2) $ if file .eqs. "" then goto not_found $ write sys$output "Search returns " + file $ if case_blind .eq. 1 then file = f$edit(file,"UPCASE") (3) $ if (f$locate("TEST",file) .ne. f$length(file)) then goto found (4) $ goto loop $found: $ write sys$output "Found a file matching TEST" $ exit $not_found: $ write sys$output "Did not find file matching TEST" $ exit

1. Set case_blind to 1 if there is an argument (and a case-blind comparison can be made).
2. Get a file ending in .TXT or .txt (because F$SEARCH is case-blind).
3. If a case-blind comparison was selected in Step 1, change the file name to uppercase to make a case-blind comparison.
4. If F$LOCATE finds a file, it will go to found:.

The following example shows the output when you run the program:

$ @test Search returns DKA300:[FISHER]test.txt;1 Did not find file matching TEST $ @test case-blind Search returns DKA300:[FISHER]test.txt;1 Found a file matching TEST

Abbreviated and Full Directory Names Listed Separately with CONDENSED File Names

Some system utilities and DCL commands, such as DIRECTORY, have a style switch to control how they display file names.

• If the style is CONDENSED, file names up to 255 bytes in length are displayed. When a file specification reaches the 255-byte limit, the directory name is abbreviated to a directory ID (DID).
• If the style is EXPANDED, file names up to 4095 bytes in length are displayed.

The following example shows a CONDENSED directory name. The DIRECTORY command considers a DID abbreviated directory name as different from the unabbreviated directory name and therefore generates a separate header when the abbreviation occurs.

$ DIR/STYLE=CONDENSED Directory DKA300:[DEEPER.aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii._ten.aaaa. bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii._ten.aaaa.bbbb.cccc.dddd.eeee.ffff.gggg. hhhh.iiii._ten.aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii._ten](1) aaaa.txt;1 Total of 1 file. Directory DKA300:[528,7036,0](2) xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.txt;1 Total of 1 file. Grand total of 2 directories, 2 files.(3)

1. With the CONDENSED style, if the combination of the directory name and file name does not exceed 255 bytes, the directory name is not shortened to a DID abbreviation.
2. With the CONDENSED style, if the combination of the directory name and file name exceeds 255 bytes, the directory name is shortened to a DID abbreviation.
3. When you issue a DIRECTORY command that displays both a full and an abbreviated directory format for the same directory name, DIRECTORY counts these as two different directories.

For more information about DIRECTORY commands, refer to the OpenVMS DCL Dictionary.

10.1.2.2 ODS-2 and ODS-5 Used Together

The following notes discuss issues related to using ODS-2 and ODS-5 together in a cluster.

Use Traditional File Names in a Mixed-Volume Environment

To avoid ODS-2 and ODS-5 file name incompatibility when working with both ODS-2 and ODS-5 volumes, and to assure backward compatibility with prior versions of OpenVMS, use only ODS-2 traditional file names.

Error Messages Can Vary Depending on Parse Style

Error messages displayed to users might vary depending on the parse style. Syntax errors that were formerly detected at the DCL level are now passed on to the file system level, RMS and XQP, for example, if the parse style is EXTENDED. As a result, the messages users receive for file syntax errors might be slightly different depending on the parse style and volume structure.

The following examples show varying error messages.

• Examples of TRADITIONAL and EXTENDED styles on an ODS-5 volume:

  $ SHOW DEVICE DKA500:/FULL Disk AABOUT$DKA500:, device type RZ25 Disk, is online, allocated, deallocate on dismount, mounted, file-oriented device, shareable. Error count 0 Operations completed 155 . . . Volume Status: ODS-5, (1) subject to mount verification, file high-water marking, write-back caching enabled. $ SET PROCESS /PARSE_STYLE=TRADITIONAL (2) $ OPEN /WRITE FILE z.z.z.z %DCL-W-PARMDEL, invalid parameter delimiter - check use of special characters \.Z\ (3) $ SET PROCESS /PARSE_STYLE=EXTENDED (4) $ OPEN /WRITE FILE z.z.z.z $ (5)

  1. The volume is ODS-5.
  2. The parse style is set to TRADITIONAL.
  3. DCL returns an error on some ODS-5 file names such as this one.
  4. The parse style is set to EXTENDED.
  5. DCL creates the file.
• Examples of TRADITIONAL and EXTENDED styles on an ODS-2 volume:

  Disk AABOUT$DKA200:, device type RZ25 Disk, is online, allocated, deallocate on dismount, mounted, file-oriented device, shareable. Error count 0 Operations completed 232 . . . Volume Status: ODS-2, (1) subject to mount verification, file high-water marking, write-back caching enabled. $ SET PROCESS /PARSE_STYLE=TRADITIONAL (2) $ OPEN /WRITE FILE z.z.z.z %DCL-W-PARMDEL, invalid parameter delimiter - check use of special characters \.Z\ (3) $ SET PROCESS /PARSE_STYLE=EXTENDED (4) $ OPEN /WRITE FILE z.z.z.z %DCL-E-OPENIN, error opening -RMS-E-CRE, ACP file create failed (5) -SYSTEM-W-BADFILEVER, bad file version number

  1. The volume is ODS-2.
  2. The parse style is set to TRADITIONAL.
  3. DCL returns an error message.
  4. The parse style is set to EXTENDED.
  5. DCL allows the file name, but XQP returns an error.
• Examples of different error messages for the same syntax error:

  $ SHOW DEVICE DKA500:/FULL Disk AABOUT$DKA500:, device type RZ25 Disk, is online, allocated, deallocate on dismount, mounted, file-oriented device, shareable. Error count 0 Operations completed 155 . . . Volume Status: ODS-5, (1) subject to mount verification, file high-water marking, write-back caching enabled. $ SET PROCESS /PARSE_STYLE=TRADITIONAL (2) $ CREATE a^<b.c %DCL-W-PARMDEL, invalid parameter delimiter - check use of special characters \^\ (3) $ SET PROCESS /PARSE_STYLE=EXTENDED (4) $ CREATE a^<b.c %CREATE-E-OPENOUT, error opening a^<b.c as output -RMS-F-SYN, file specification syntax error (5)

  1. The volume is ODS-5.
  2. The parse style is set to TRADITIONAL.
  3. DCL returns an error message for a syntax error.
  4. The parse style is set to EXTENDED.
  5. RMS returns a different error message for the same syntax error.

Be Aware of Implicit File Name Output

Be wary of defaults when you allow utilities to create output files based on the file name being processed. Be sure you know where a file is being placed so you will not inadvertently try to place a file with an extended name on an ODS-2 volume.

The following examples show files being placed somewhere you might not expect:

• An error results if an application or a utility attempts to write an ODS-5 extended file name to an ODS-2 (DKA200:) volume; for example:

$ SHOW DEFAULT DKA200:[DOREO] $ DUMP /OUTPUT DKA500:[DOREO]This^_is^_a^_file.Dat %DUMP-E-OPENOUT, error opening DKA200:[DOREO]THIS^_IS^_A^_FILE.DMP;as output -RMS-E-CRE, ACP file create failed -SYSTEM-W-BADFILENAME, bad file name syntax

The output file specified with the /OUTPUT qualifier defaults to the same name as the input file, with .DMP as the file type, in the default directory. When the input file specification is an extended name on an ODS-5 volume, the .DMP file must have a traditional name, because it will be written to an ODS-2 volume. As a result, an error occurs.

• A batch command file fails to execute if all of the following conditions are true:
  • A log file is requested implicitly or explicitly.
  • The implicit or explicit log file specification has an extended name (that is, the name is non-ODS-2-compliant).
  • The log file is to be created on an ODS-2 volume.
  
  The batch command file does not execute because a log file cannot be created. Most frequently, this situation occurs when the logical name SYS$LOGIN refers to an ODS-2 volume; this is because log files are implicitly created on the SYS$LOGIN device. In addition, if notification is disabled, you are not notified that your batch job did not execute.
  To avoid the problem, use the /LOG= qualifier and an ODS-2-compliant log file specification when you submit command files with ODS-5 extended names.

The following notes discuss Extended File Specifications issues related to system architecture.

Extended File Names Are Not Visible from a VAX System

Although you can mount ODS-5 volumes on a VAX, if you log in to a VAX system, ODS-5 extended file names are not visible. In their place, you see a pseudoname:

• On VAX, if you attempt to display a file name that contains 2-byte Unicode characters, the pseudoname displayed is the following:
  \PUNICODE\.???
• Any other name that is not a legal ODS-2 name is displayed as
  \PISO_LATIN\.???

For example, the same directory listings as they appear on Alpha and VAX systems are:

• On an Alpha system:

  $ DIRECTORY DPA100:[TEST] Directory DPA100:[TEST] Accounting^_data.lis;1 atest.txt;1

• On a VAX system:

  $ DIRECTORY DPA200:[TEST] Directory DPA200:[TEST] \PISO_LATIN\.??? ATEST.TXT

In addition, the directory depth on a VAX is limited to 8 (or 16, using rooted logicals).

Physical Backups of ODS-5 Volumes on VAX Systems

On OpenVMS VAX systems, BACKUP supports ODS-5 volumes only when you specify the /PHYSICAL qualifier to back up a volume. The BACKUP /PHYSICAL command causes BACKUP to make a block-by-block physical backup of the disk, ignoring the structured contents of the disk.

On Alpha systems, you can use either the BACKUP /IMAGE or BACKUP /PHYSICAL command.

10.2 Considerations Before Enabling ODS-5 Volumes

ODS-5 is implemented on OpenVMS primarily to provide enhanced file sharing capabilities for users of Advanced Server for OpenVMS 7.2³ as well as DCOM and Java applications.

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 new syntax for file names that is allowed on ODS-5 volumes cannot be fully utilized on ODS-2 volumes. Because pre-Version 7.2 Alpha systems cannot access ODS-5 volumes, and Open VMS Version 7.2 VAX systems have limited ODS-5 functionality, you must be careful where and how you enable ODS-5 volumes in mixed-version and mixed-architecture OpenVMS Clusters.

The following sections comprise a summary of how enabling ODS-5 volumes can impact system management, users, and applications.

10.2.1 Considerations for System Management

RMS access to deep directories and extended file names is available only on ODS-5 volumes mounted on OpenVMS Alpha V7.2 systems. Compaq recommends that ODS-5 volumes be enabled only on a homogeneous OpenVMS Cluster running Alpha V7.2 and later.

If ODS-5 is enabled in a mixed-version or mixed-architecture OpenVMS Cluster, the system manager must follow special procedures and be aware of specific restrictions on mixed-version and mixed-architecture OpenVMS Clusters with ODS-5 volumes enabled:

• Users must access ODS-5 files and deep directories from OpenVMS Alpha V7.2 systems only, because these capabilities are not supported on earlier versions.
• Users who have created deep directories can view those directories only from OpenVMS Alpha V7.2 systems.
• Pre-Version 7.2 systems cannot mount an ODS-5 volume nor read ODS-2 or ODS-5 file names on that volume.

Section 10.2.2 describes in greater detail the limitations of ODS-5 support for users in a mixed-version or mixed-architecture OpenVMS Cluster.

Most unprivileged applications will work with most extended file names, but some may need modifications to work with all extended file names. Privileged applications that use physical or logical I/O to disk and applications that have a specific need to access ODS-5 file names or volumes may require modifications and should be analyzed. See the website www.openvms.compaq.com for a list of fully supported OpenVMS applications. Section 10.2.3 describes in greater detail the impact of ODS-5 on OpenVMS applications.

Section 10.3.1 contains more information for determining the levels of support for Extended File Specifications.

10.2.2 Considerations for Users

A user on an OpenVMS Alpha Version 7.2 system can take advantage of all Extended File Specifications capabilities on ODS-5 volumes mounted on an OpenVMS Alpha Version 7.2 system.

A user on a mixed-version or mixed-architecture OpenVMS Cluster is subject to some limitations in ODS-5 functionality. Section 9.1.2.2 lists those restrictions that exist on a mixed-version OpenVMS Cluster. Section 9.1.2.3 lists those restrictions that exist on a mixed-architecture OpenVMS Cluster.

10.2.3 Considerations for Applications

ODS-5 functionality can be selected on a volume-by-volume basis. If ODS-5 volumes have not been enabled on your system, all existing applications will continue to function as before. If ODS-5 volumes have been enabled, you need to be aware of the following changes:

• OpenVMS file handling and command line parsing have been modified to enable them to work with extended file names on ODS-5 volumes while still being compatible with existing applications. The majority of existing, unprivileged applications will work with most extended file names, but some may need modifications to work with all extended file names.
• Privileged applications that use physical or logical I/O to disk may require modifications and should be analyzed. Applications that have a specific need to access ODS-5 file names or volumes should be analyzed to determine if they require modification.

On ODS-5 volumes, 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:

• Internal knowledge of the file system, including knowledge of:

  The data layout on disk
  The contents of file headers
  The contents of directory files

• File parsing tailored to a particular on-disk structure.
• Assumptions about the syntax of file specifications, such as the placement of delimiters and legal characters.
• Assumptions about the case of file specifications. Mixed and lowercase file specifications will not be converted to uppercase, which can affect string matching operations.
• Assumptions that file specifications are identical between RMS and the file system.

See OpenVMS Programming Concepts Manual for further discussion of the support status of OpenVMS applications.

10.3 Guidelines for Using Extended File Specifications on OpenVMS Applications

It is essential that system managers perform the following steps before enabling ODS-5:

• Review all ODS-5 considerations. (See Section 10.2.1.)
• Understand the support levels for different OpenVMS (See Section 10.3.1.) applications.
• Segregate applications that do not support ODS-5 or have not been tested with ODS-5 names or volumes. (See Table 10-1.)
• Review the guidelines for setting users' expectations in Section 10.1.2.

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