Technical data

2.4 Determining Which File System to Use
The first step in managing your TCP/IP Services system is to decide which file
system to use. NFS on OpenVMS enables you to set up and export three different
kinds of file systems:
• OpenVMS On-Disk Structure (ODS-2) file system, in which devices,
directories, and files are stored on a Files-11 formatted disk
• OpenVMS On-Disk Structure (ODS-5) file system, which enables creation
and storage of files with extended file names for compatibility with other file
systems, such as Windows.
• UNIX, or container, file system, builtontopofanOpenVMSsystem.Ifyou
are not familiar with OpenVMS file systems, refer to the OpenVMS System
Manager’s Manual: Essentials to learn how to set up and initialize a Files-11
disk. As Figure 2–2 shows, both file systems are structured as hierarchical,
multilevel directories. On OpenVMS systems, the top level is called the master
file directory, or MFD. This directory contains all the directories and reserved
system files. The directory is named [000000]. On UNIX systems, the top-level
directory is called the root, or / .
Table 2–12 lists the NFS server features available to non-OpenVMS clients based
on file system choice.
Table 2–12: NFS Server Features Available to Non-OpenVMS Clients
Features
ODS-2 OD2–2 with name
conversion
ODS-5 Container file
system
Files easily shared
between remote
clients and local
OpenVMS users
Yes Yes Yes No
Mixed case, special
characters, and extra
dots in file names
No Yes Yes Yes
Long file names No No Yes Yes
File names look
thesametoremote
clients and local
OpenVMS users
Uppercase
to local
users,
lowercase
to remote
clients
No Yes N/A
Support for hard
links, symbolic links,
special files
No No No Yes
UNIX compatible
timestamps
No No No Yes
Case-sensitive
lookup
N/A Yes No Yes
The dual cataloguing of files to both OpenVMS file systems limits the set of DCL
commands. OpenVMS utilities, such as BACKUP, can use standard methods to
access the files. However, except for backing up and restoring files, you should not
use DCL commands to manipulate files in a container file system.
Understanding OpenVMS and UNIX Implementations 2–11