Storage, Volumes, and File Systems
OpenVMS storage is organized into volumes formatted with the Files-11 On-Disk Structure (ODS-2 and ODS-5). A volume has a home block, a file header index (INDEXF.SYS), and directories; each file is described by a file header (FH) that contains the file's extents and protection. Candidates should understand the difference between ODS-2 (case-insensitive, limited filename length) and ODS-5 (long names, case preservation, deeper directories), and that ODS-5 support must be enabled on the volume.
Know volume management: INITIALIZE creates the volume structure, MOUNT attaches it to the system, and DISMOUNT releases it. The system disk holds the page, swap, and dump files. Logical volumes can be built with shadowing (host-based volume shadowing) for redundancy, and with volume sets for spanning. Understand that mounting is required before file access, and that MOUNT qualifiers (/NOSHARE, /FOREIGN) change behavior - a foreign mount treats the volume as unformatted data.
Traps: assuming a dismounted volume is inaccessible only to the dismounting process (it is systemwide); confusing logical volume shadowing with controller-based RAID; and forgetting that ANALYZE/DISK_STRUCTURE checks and repairs file-system consistency. Also be ready for questions on disk quotas and on the difference between a file's UIC protection and its ACL.
Rule of thumb: INITIALIZE → MOUNT → use → DISMOUNT is the lifecycle; if a volume shows as foreign or unformatted, check whether it was initialized and mounted with the right qualifiers.