DESIGN OF A ROBUST FILE SYSTEM. AS PER DISCUSSIONS WITH GJC, PACE, AND DG.


PARTITION:

	AN OBJECT THAT IS MOUNTED AND DISMOUNTED. USE SI:MOUNT-DISK-PARTITION.
	YOU CAN THINK OF IT AS A LINEAR SEQUENCE OF BLOCKS ON DISK.

BLOCK:

	THE DATA IN THE PARTITION IS MADE UP OF EQUAL SIZED BLOCKS. A BLOCK MAY BE 1 OR MORE
	PAGES. THE BLOCK IS THE BASIC UNIT OF MANIPULATION.
        A BLOCK LOOKS SOMETHING LIKE THIS:

	[REFERENCE-COUNT]
	[CREATION-DATE]
	[CREATION-AUTHOR-ID]
	[REVISION-DATE]
	[REVISION-AUTHOR-ID]
	[FILE-ID]
	[FILE-NAME]
	[FILE-TYPE]
	[FILE-VERSION]
	[FILE-DATA-TYPE]
	[FILE-DATA-SEQUENCE-NUMBER]
	[FILE-DATA-SEQUENCE-LENGTH]
	...DATA...


FILES:
	GIVEN A FILE-ID YOU CAN SCAN ALL THE BLOCKS IN A PARTITION AND
	FIND ALL BLOCKS THAT MAKE UP THAT FILE. IF YOU SORT THE BLOCKS
        BY FILE-DATA-SEQUENCE-NUMBER THEN YOU WILL HAVE YOUR FILE.


ALLOCATION:
	YOU CAN SCAN ALL THE BLOCKS TO FIND ONES THAT ARE FREE, MARK THEM RESERVED,
	THEN MARK THEM USED. WHEN A FILE IS DELETED YOU SCAN FOR ITS BLOCKS
	AND MARK THEM FREE. AS AN EFFICIENCY FEATURE YOU CAN ALSO HAVE A FILE AS
	A PAGE-USAGE-TABLE. THIS WOULD MAKE IT FASTER TO FIND FREE BLOCKS.

DIRECTORIES:
	AS AN OPTIMIZATION AND USER INTERFACE FEATURE YOU CAN HAVE SOME FILES
	CALLED DIRECTORIES. THESE HAVE PRETTIER NAMES FOR FILES AND ALSO
	GIVE A LIST OF BLOCKS IN THE FILE. THIS WAY YOU DONT NEED TO SCAN
	THE WHOLE PARTITION EVERYTIME YOU WANT TO OPEN A FILE.