; - FILE FNDFIL.DOC
;

	Fndfil is a program that searches all file headers on a disk trying
to locate a logical block within a file.  This can be useful when the
Error Logger indicates disk errors.  The error log reports certain errors by
logical block number (LBN).  The error log report of what LBN's are bad does 
not lend itself to easily resolving these bad spots on the disk.  This 
program helps you to identify what files these LBN's are in.  It additionally
computes the virtual block number within the identified file.  Once identified,
individual blocks of corrupted files can hopefully be restored or recreated 
from backups and thus eliminating the cause of the system errors.


	Please direct comments and suggestions to:



		Barry Zion
		The Federal Reserve Bank of N.Y.
		95 Maiden Lane  -  7th floor annex
		New York, N.Y. 10045

		tel: (212) 791-5585


	To run the program:

	>run fndfil
			   DEVICE AND UNIT TO SEARCH ON:ddn:
		    DECIMAL LOGICAL BLOCK TO SEARCH FOR:nnnnnn


	where ddn: is a device such as DB1:
	and nnnnnn is an LBN in the range 1 - max
		where max is the highest LBN for the particular disk



	Fndfil outputs a header message indicating the 24-bit LBN it is 
searching in octal.  Then if any file header's retrieval pointers are mapping
the LBN various information pertaining to the header are displayed.  Once the 
program finishes you may wish to verify via a directory command that  the file
is indeed accessible.  One note of importance is that the FILE ID field 
displayed by fndfil may be different from that displayed by a "PIP/FU" command.
This is because the map area of the file header could not contain enough 
retrieval pointers to map the entire file.  An extension header was necessary
to map all blocks the file.  This occcurs when  a file composed of 
more than 102 discontinuous segments or more than 26,112 blocks.  Another 
way of accessing the file is to use DMP and dump the entire file header as
follows:

		>DMP TI:=ddn:[uic]filnam/HD/BL:0:0

	Substitute in the file name(s) output by fndfil and check the various
file header fields.

	The indication that an extension header is in use is a non-zero
M.EFNU and M.EFSQ field in the map area.  The values in these fields will
be the file id of the extension header.  


	FNDFIL will continue searching all file headers even if a file 
is found.  This is extra insurance in case of a severely corrupt file system
in which a block is allocated to more than one file.  When all file headers 
are exhausted a file header summary is displayed showing in use and free file 
headers as follows:

SEARCH OF ALL FILE HEADERS COMPLETED ON DR2:

FILE HEADER SUMMARY

     SCANNED IN USE FILE HEADERS :   3090
     SCANNED  FREE  FILE HEADERS :   3173
FILE HEADERS YET TO BE ALLOCATED :   1836
------------------------------------------
MAX FILE HEADERS FROM HOME BLOCK :   8099



		FNDFIL CAN BE BUILT BY INVOKING @FNDFILBLD.CMD

	This command file will assemble and task build all modules of fndfil.
And when you're ready to fix all the bugs I so cleverly and unknowingly left
in the program you can use @FNDFILODT.CMD.  This will create a task FNDFILODT
that includes ODT.  


*******************************************************************************
		R M S    f a n s    t a k e    n o t e


	As an extra added bonus for all of you RMS fans out there I have
included FABERR.MAC and RABERR.MAC.  These two routines can be used as error
routines for all of your RMS calls involving FAB's and RAB's.  When called
they will translate all of the fields of the associated RMS block (FAB or RAB)
into intelligible english.  Sorry, I didn't bother with the STS or STV values.
You will still have to look them up in the RMS macro ref manual Table A-2 or
use online help "HELP RMS ERROR".

*******************************************************************************

	To test FNDFIL use the command file @tstfndfil.cmd.  This command 
file will DMP the file header of the newly created FNDFIL.TSK.  You can then 
use this data as input to the program.  This will see if fndfil can at least 
find itself!  Enter the LBN of the first (or any other) block of FNDFIL.TSK as 
specified by the dmp.  A sample DMP follows:


Dump of DB1:[301,53]FNDFIL.TSK;2 - File ID 17576,5,0
				 File header


HEADER AREA
	H.IDOF  	027
	H.MPOF		056
	H.FNUM,
	H.FSEQ		(17576,5)
	H.FLEV		401
	H.FOWN		[301,053]
	H.FPRO		[RWED,RWED,RWED,R]
	H.UCHA		200 =  UC.CON
	H.SCHA		000 =  

	H.UFAT
		F.RTYP	001 = R.FIX
		F.RATT	000 =    
		F.RSIZ	1000 = 512.
		F.HIBK	H:0 L:000333 = 219.
		F.EFBK	H:0 L:000334 = 220.
		F.FFBY	0 = 0.
		(REST)
		000000 000000 000000 000000 000000 000000 000000 000000
		000000
IDENTIFICATION AREA
	I.FNAM,
	I.FTYP,
	I.FVER		FNDFIL   .TSK;2
	I.RVNO		1
	I.RVDT		26-MAR-85
	I.RVTI		14:44:37
	I.CRDT		26-MAR-85
	I.CRTI		14:43:16
	I.EXDT		--
MAP AREA
	M.ESQN		000
	M.ERVN		000
	M.EFNU,
	M.EFSQ		(0,0)
	M.CTSZ		001
	M.LBSZ		003
	M.USE		002 = 2.
	M.MAX		314 = 204.
	M.RTRV				*********************************
	SIZE	LBN			*********************************
	219.	H:### L:###### = NNNNNN.<<<----- enter this as the LBN  
CHECKSUM				*********************************
	H.CKSM		020145		*********************************