ODS-2
ODS-2, or On-Disk Structure-2, is a Files-11 file system. This is the most widely used file system on OpenVMS; system disks can only be ODS-2. The most notable feature of this system as compared to the other most widely used one, ODS-5, is that it is not case-sensitive or case-preserving, and that it does not support hard links.
ODS-2 is used to share data between VAX and Alpha with full compatibility.
Here is what an ODS-2 disk looks like:
$ sh dev dka0: /full
Disk SMAN01$DKA0:, device type RZ73, is online, mounted, file-oriented device,
shareable, available to cluster, error logging is enabled.
Error count 0 Operations completed 8514
Owner process "" Owner UIC [SYSTEM]
Owner process ID 00000000 Dev Prot S:RWPL,O:RWPL,G:R,W
Reference count 94 Default buffer size 512
Total blocks 3907911 Sectors per track 7
<...>
Volume Status: ODS-2, subject to mount verification, protected subsystems
enabled, file high-water marking, write-through XFC caching enabled,
write-through XQP caching enabled.
File Name Restrictions
ODS-2 supports the following character set:
- A-Z
- 9-0
- hyphen (-)
- dollar sign ($)
- underscore (_)
The maximum length of file names and extensions is 39 characters.