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From: jerry@oliveb.UUCP (Jerry F Aguirre)
Newsgroups: comp.unix.questions
Subject: Re: File system problems
Message-ID: <4076@oliveb.UUCP>
Date: Sat, 29-Aug-87 00:00:17 EDT
Article-I.D.: oliveb.4076
Posted: Sat Aug 29 00:00:17 1987
Date-Received: Sun, 30-Aug-87 07:36:52 EDT
References: <8467@brl-adm.ARPA>
Reply-To: jerry@oliveb.UUCP (Jerry F Aguirre)
Organization: Olivetti ATC; Cupertino, Ca
Lines: 33
Keywords: restore dump Unix ctime
Summary: Yes, you will do a level 0 after a restore

In article <8467@brl-adm.ARPA> KFL@AI.AI.MIT.EDU (Keith F. Lynch) writes:
>He has also said that after using doing a restore of a zero level dump,
>it is necessary to immediately do another zero level dump or the file
>system will get hosed again.  Is this really needed?  If so, can it be
>done overnight, to /dev/null?

1/half true.  Under 4.1BSD and before the restor (sic) worked on the raw 
file system.  This meant that the restored files had the same inode
number and ctime.  (The only thing different would be the actual data
block addresses and that is desirable.)

After 4.2BSD, "restore" worked on the mounted file system and did creat,
write, link, etc. calls to put the files on disk.  Because of this the inode numbers would almost certainly be different.  Also, while the
restore could reset the atime and mtime using utimes(2), there is no
system call to reset the ctime.

So, the inodes are different and the ctime is the time of restore.  The
updated ctimes will force the next dump, of whatever level, to dump
every file that was restored.  If you are planning a small level 9 dump
and the entire file system gets dumped this can cause confusion.  The
best way to avoid confusion is to do another level 0 dump.  The only
rush is to do it before, or in place of, the next regular dump of that
file system.

People have suggested playing with the system date or editing dumpdates.
This will not fix anything because the inode numbers have changed.
That is the kind of thing that can cause corrupted files if you have to
do another restore later.

The important thing to remember is that all the files really have been
changed (as far as dump/restore is concerned) and will get dumped.

					Jerry Aguirre