Using Programs Written for Minidisks on Shared SFS Files

Programs that use FS macros, OS simulation, DOS simulation, and the EXECIO command will also work correctly in certain file sharing situations.

SFS directory control directories have sharing characteristics similar to those of minidisks. Programs are likely to need few modifications (if any) to work correctly on files residing in directory control directories.

SFS file control directories permit more concurrent sharing of files than minidisks. Programs written for minidisks will work correctly only in certain file sharing situations, such as:
  • Reading shared files which are not locked or being updated by other users.
  • Updating (but not replacing) shared files that meet ALL of the following criteria:
    • The file is not concurrently locked or open for update by other users.
    • The file is being referenced through a directory accessed read/write.
    • The user is authorized to write to the file.

    (For more information about programs that update and replace files, see Modifying Programs That Replace Files.)

Regardless of whether directory control or file control directories are being used, programs written for minidisks may act differently in certain file sharing cases, and might require changes to work correctly. For example, you might need to change your program for:
  • New return codes
  • File space usage considerations
  • Files shared through aliases
  • Other user's directories accessed as read/write
  • Reading shared files that are locked by other users
  • Replacing shared files
  • Update-in-place processing.

The conditions described apply to programs coded in high-level languages as well as programs coded in assembler language.