Technical data

Managing Storage Media
9.1 Understanding Storage Media Concepts
9.1.2.1 System and User Disk Support
Restrictions and suggestions for using Extended File Specifications on your
system are as follows:
• You can mount an ODS-5 volume only on an OpenVMS VAX or an Alpha
Version 7.2 or later system. Most applications can access only traditionally
named files on a VAX system.
• Compaq does not support creating the system disk as (or changing it to) an
ODS-5 volume.
9.1.2.2 Mixed-Version Support
Users on OpenVMS 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 or correctly handle extended
file names.
The following sections describe support on OpenVMS Version 7.2 and on prior
versions of OpenVMS in a mixed-version cluster.
Users on OpenVMS Version 7.2 Systems
Users on OpenVMS Version 7.2 systems can continue to access pre-Version 7.2
files and directories. For example, they can perform all of the following actions:
• Create and access deep directory structures on ODS-2 volumes.
• Read a BACKUP save set created on an earlier version of OpenVMS.
• 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 Systems with Versions Prior to OpenVMS 7.2
On mixed-version clusters, some restrictions exist. Users on a version of
OpenVMS prior to Version 7.2 have these limitations:
• 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, or by an MSCP
or QIO server.
• Cannot successfully create or restore an ODS-5 image save set. However,
these users can successfully restore ODS-2-compliant file names from an
ODS-5 save set.
9.1.2.3 Mixed-Architecture Support
All Extended File Specifications capabilities are available on OpenVMS Alpha
systems. Nearly all the current ODS-2 disk and file management functions
remain the same on both VAX and Alpha Version 7.2 systems; however, extended
file naming and parsing are not available on VAX systems.
The following sections 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 clusters, the following limited
Extended File Specifications capabilities are available on OpenVMS VAX systems:
• Ability to mount and manage an ODS-5 disk
• Ability to write and manage ODS-2-compliant files on an ODS-5 disk
Managing Storage Media 9–9