Technical data

Managing Storage Media
9.1 Understanding Storage Media Concepts
BACKUP Limitations
On an OpenVMS VAX system, users 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.
Users can also perform a disk-to-disk copy from ODS-5 to ODS-2 as long as they
do not specify /IMAGE.
For more information, refer to the OpenVMS Guide to Extended File
Specifications.
9.1.2.4 Network Support
For OpenVMS Version 7.2 and later, the length of a file specification that can be
sent over the network using DECnet is shorter than the maximum size of a file
specification without the use of a network.
9.1.2.5 Enabling Extended File Specifications Features
To enable Extended File Specifications On-Disk Structure features for a volume
on an OpenVMS Alpha system, you must perform one of the following actions:
Task Reference
Initialize a new volume as ODS-5 Section 9.3.3
Convert an existing volume from ODS-2 to ODS-5 Section 9.5.5.1
Creating ODS-5 volumes allows you to take advantage of extended file names for
Compaq Advanced Server for OpenVMS clients; you can see and manage these
names from OpenVMS Alpha systems.
Note
Extended File Specifications are not available on systems running
versions of OpenVMS Alpha prior to Version 7.2. On these systems,
you cannot mount ODS-5 volumes nor take advantage of extended file
names on an OpenVMS file system.
9.1.3 Tape Concepts
The file storage system for magnetic tapes is based on the standard magnetic
tape structure as defined by ISO 1001–1986, which is compatible with several
national standards such as ANSI X3.27–1987.
For more information about tape concepts, refer to the Guide to OpenVMS File
Applications.
Table 9–6 defines terms that apply to magnetic tapes.
Table 9–6 Terms Related to Magnetic Tapes
Term Definition
Block On magnetic tape, the size of a block is determined by the user. On ODS disks, a
block is fixed at a size of 512 bytes.
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9–10 Managing Storage Media