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From: nz@wucs.UUCP
Newsgroups: net.unix-wizards,net.bugs.4bsd
Subject: Re: 4.2BSD restore(8)
Message-ID: <1631@wucs.UUCP>
Date: Thu, 1-May-86 15:54:47 EDT
Article-I.D.: wucs.1631
Posted: Thu May  1 15:54:47 1986
Date-Received: Sat, 3-May-86 19:02:12 EDT
References: <2066@hao.UUCP> <801@oliveb.UUCP> <974@tektools.UUCP>
Reply-To: nz@wucs.UUCP (Neal Ziring)
Distribution: net
Organization: Washington U. Engineering Computer Lab
Lines: 83
Keywords: 4.2BSD restore ctime
Xref: watmath net.unix-wizards:17896 net.bugs.4bsd:2079

In article <974@tektools.UUCP> richl@tektools.UUCP (Rick Lindsley) writes:
 > In article <801@oliveb.UUCP> jerry@oliveb.UUCP (Jerry Aguirre) writes:
 > > I have also noticed that after a restore all the files marked as
 > > changed and will go on the next dump.  [ ... ]
 > 
 > If you really did just spend hours restoring the file system, then you
 > have restored all or virtually all of the file system. If you don't
 > want to do a level 0 dump, simply edit /etc/dumpdates to reflect
 >  ...

In fact, this problem is due to a quirk in a dump/restore, the
restored files have the correct modification time, but their creation
times are the time of the restore!

Repeat-By:
	Put a file system on a dummy partition, and do a level 0
	dump(8) of it.  Wait a few minutes.  Then, trash the partition
	and restore it fully from your dump.  Change one file.
	Now, do a level 1 backup with dump(8).  The backup should be
	extremely small (one file) but it isn't!  It is the whole
	filesystem!

To Fix:
	Change dump so that it looks only at the modification time, not
	the creation and modification times.

	Here is a diff for the file dump/dumptraverse.c.  My change is
	bracketed by some #ifdef-#else-#endif.s, you can take those out
	if you like.

*** /tmp/,RCSt1018628	Thu May  1 14:40:45 1986
--- dumptraverse.c	Fri Apr  4 11:34:08 1986
***************
*** 38,43
  	BIS(ino, clrmap);
  	if(f == IFDIR)
  		BIS(ino, dirmap);
  	if ((ip->di_mtime >= spcl.c_ddate || ip->di_ctime >= spcl.c_ddate) &&
  	    !BIT(ino, nodmap)) {
  		BIS(ino, nodmap);

--- 38,44 -----
  	BIS(ino, clrmap);
  	if(f == IFDIR)
  		BIS(ino, dirmap);
+ #ifndef MTIME_ONLY
  	if ((ip->di_mtime >= spcl.c_ddate || ip->di_ctime >= spcl.c_ddate) &&
  #else
  	if ((ip->di_mtime >= spcl.c_ddate ) &&
***************
*** 39,44
  	if(f == IFDIR)
  		BIS(ino, dirmap);
  	if ((ip->di_mtime >= spcl.c_ddate || ip->di_ctime >= spcl.c_ddate) &&
  	    !BIT(ino, nodmap)) {
  		BIS(ino, nodmap);
  		if (f != IFREG && f != IFDIR && f != IFLNK) {

--- 40,48 -----
  		BIS(ino, dirmap);
  #ifndef MTIME_ONLY
  	if ((ip->di_mtime >= spcl.c_ddate || ip->di_ctime >= spcl.c_ddate) &&
+ #else
+ 	if ((ip->di_mtime >= spcl.c_ddate ) &&
+ #endif
  	    !BIT(ino, nodmap)) {
  		BIS(ino, nodmap);
  		if (f != IFREG && f != IFDIR && f != IFLNK) {

	We use this modified version some of the time.  I 
	noticed the problem, and made the changes, after a series of
	disk crashes and fixes that required full restores.  Boy, 
	the next weekends backups were big!  Hmmm...

	Anyway, I hope this is helpful to some folks out there.
-- 
...nz (Neal Ziring at WU ECL  -  we're here to provide superior computing.)

	{seismo,ihnp4,cbosgd}!wucs!nz   OR   nz@wucs.UUCP

    "You could get an infinite number of wires into this !*$$#!?! junction 
                         box, but we usually don't go that far in practice"
				--   Employee of London Electricity Board, 1959