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.
Here is what an ODS-2 disk looks like:
$ sh dev dka0: /full Disk SMAN01$DKA0:, device type RZ73, is online, mounted, file-oriented device, shareable, available to cluster, error logging is enabled. Error count 0 Operations completed 8514 Owner process "" Owner UIC [SYSTEM] Owner process ID 00000000 Dev Prot S:RWPL,O:RWPL,G:R,W Reference count 94 Default buffer size 512 Total blocks 3907911 Sectors per track 7 <...> Volume Status: ODS-2, subject to mount verification, protected subsystems enabled, file high-water marking, write-through XFC caching enabled, write-through XQP caching enabled.
File Name Restrictions
ODS-2 supports the following character set:
- hyphen (-)
- dollar sign ($)
- underscore (_)
The maximum length of file names and extensions is 39 characters.