xerox 19771025 Comments On Pilot File System free download

File name 19771025_Comments_On_Pilot_File_System.pdf

Inter-Office Memorandum To Bill Lynch Date October 25, 1977 From Peter Bishop Location Palo Alto Subject Comments on Pilot File System Organization SDD XEROX SOD ARCHIVES XEROX I have read and understood PageS ___________To _________ Filed on: fi1erec.memo Reviewer I of Pa,es ------ Date Ref.!1160D~ 35," The following are a set of thoughts and recommendations on the Pilot File System. They range from specific proposals to continuing discussions on various points. 1. Making Files Objects I think that there will be several pieces of software on OIS that will need to treat files as objects. In particular, the CopyDisk operation will define a Copy operation on every type of file that must correct any filelDs kept within the file. Plans seem to be solidifying to make documents reside in a single file. Documents will be treated as objects by the desktop. A sophisticated scavenger needs to treat files as objects so that when a single page is lost, the rest of the information in the file can be saved. If files are to be treated as objects, then it would be valuable to have one of the attributes of a file be its type. This would be an 8 or 16 bit number that would be carefully allocated to various subsystems so that no two subsystems would have the same type of file unless the software to manipulate the file was interchangeable. In order for the scavenger to be able to use this type, however, it is necessary for the type of the file to be placed in the page header in addition to the filelD and the page number within the file. This protects against loss of the page that contains the attributes of a file. 2. Owner Counts The original Concepts and Facilities suggested that each file should have a reference count. I do not believe that files should have reference counts, but I think that it would be valuable for files to have owner counts. Directories own the files contained in the directory. Similarly, the desktop owns any file that is currently sitting on the desktop in iconic form or as an enlarged window. It should be possible for the same file to be in a directory and on the desktop at the same time. When