[Info-vax] INDEXF.SYS

[JF Mezei]

Different way to explain:

every file on VMS has a file number (file ID). (dir/full shows it, it
consists of 3 numbers)


INDEXF is a sorted list of all file IDs. It contains the file header
(where the file is physically located on the hard disk), file name, and
many file atrributes (what DIR/FULL shows you for instance comes frm
INDEXF.SYS).


INDEXF doesn't know what directory the
file is in.

However, when you use the system and do a directory of files, the
directory knows the file IDs of the files in that directory and uses
INDEXF.SYS to get their attributes.


what ANALYZE/DISK/REPAIR does (along with other tasks) is to make a list
of all files by walking through the directory tree, and then compare
this with all the files located in INDEXF.SYS

If it finds files that are in INDEXF.SYS but not in any directory on
that disk, it will create a directory entry for that file in [SYSLOST]


Consider a ase of the directory [FOOD.CHOCOLATE] which might contain 10
recipes for chocolate cakes.


There are ways where one can screw the system and
DELETE [FOOD]chocolate.dir;1


If you do this, then the chocolate.dir;1 file gets deleted.  But the 10
files that were in it are untouched, except there is no longer any way
for you to get of list of then or access them using their file names.


ANALYZE/DISK/REPAIR will spot that those 10 files exist but no directory
points to them and will get entered in the [SYSLOST] directory.