Files-11 - Other Files

Other Files

  • Storage bitmap file: BITMAP.SYS
The bitmap file is responsible for storing information regarding used and available space on a volume. It contains the storage control block (SCB), which includes summary information detailing ???, and the bitmap, an array of bits to indicate if a cluster of blocks on the disk is free or allocated. In early versions of VMS the cluster comprised 3 blocks but as disk sizes have increased, so has the cluster size.
  • Bad block file: BADBLK.SYS
The bad block file contains all of the known bad blocks on the physical volume. The purpose is to prevent the system from allocating them to files. This file was used more in the early days when disks were typically manufactured with more bad patches on the surface.
  • Volume set list file: VOLSET.SYS
The volume set list is located on volume 1 of a volume set, and contains a list of labels of all volumes in the set, and the set's volume name.
  • Continuation file: CONTIN.SYS
When a file on a multi-volume set crosses the boundary of two constituent volumes, the continuation file is used as its extension header and describes the volume where the rest of the file can be found.
  • Quota file: QUOTA.SYS
The quota file contains information of each UIC's disk space usage on a volume. It contains a record for each UIC with space allocated to it on a volume, along with information on how much space is being used by that UIC. NOTE: The DISK QUOTA feature is optional and the file will only exist if the feature was ever enabled.
  • Volume security profile: SECURITY.SYS
The volume security profile contains the volume's owner UIC, the volume protection mask, and its access control list.
  • GUID Partitioning Table: GPT.SYS
This file overlays and protects the MBR (Master Boot Record) and GPT (GUID Partitioning Table) disk structures utilized for and by the Extensible Firmware Interface-compliant firmware. This file is created by default during OpenVMS I64 disk initialization, and is optionally created (with INITIALIZE/GPT) on OpenVMS Alpha.

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