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Date:      Mon, 03 Jul 2006 16:46:39 +0100
From:      Alex Zbyslaw <xfb52@dial.pipex.com>
To:        backyard1454-bsd@yahoo.com
Cc:        freebsd-questions@freebsd.org
Subject:   Re: problems with Nice and Dump in FreeBSD 6.1-Current (Stable-#5)
Message-ID:  <44A93BDF.4050601@dial.pipex.com>
In-Reply-To: <20060630191357.43491.qmail@web81615.mail.mud.yahoo.com>
References:  <20060630191357.43491.qmail@web81615.mail.mud.yahoo.com>

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backyard1454-bsd@yahoo.com wrote:

>--- Alex Zbyslaw <xfb52@dial.pipex.com> wrote:
>
>  
>
>>backyard1454-bsd@yahoo.com wrote:
>>
>>    
>>
>>>I forgot about nice being interal to csh, that is
>>>likely to source of my problems...
>>>
>>>I use this for a dump
>>>
>>>dump -0 -C 32 -f - |bzip2 --best | dd
>>>      
>>>
>>of=/foo/bar.dbz2
>>    
>>
>>>and then on a restore
>>>
>>>bzip2 -dc | (cd /foo; restore -r -f -)
>>>
>>>
>>>the error I get is
>>>
>>>expected 234234 got 234237
>>>expected 234235 got 234238
>>>expected 234236 got 234239
>>>... ...
>>>
>>>expected 234250 got 234267
>>>
>>>which fills up the screen with seemingly corruption
>>>errors, then the restore bails with an error asking
>>>      
>>>
>>if
>>    
>>
>>>I wish to continue, if I continue it fails. I will
>>>      
>>>
>>get
>>    
>>
>>>a screen dump of the error when I can dig up the
>>>corrupt dump file, and or make a new one. I believe
>>>the error is something about inodes missing or
>>>      
>>>
>>being
>>    
>>
>>>corrupted.
>>>
>>>this exact command syntax works on everything but
>>>      
>>>
>>my
>>    
>>
>>>usr filesystem.
>>> 
>>>
>>>      
>>>
>>The restore man page does tell you why this happens
>>(I know because I 
>>was just reading it today :-))
>>
>>You are doing this dump on a Live Filesystem.  To do
>>that use the -L 
>>option to dump (FreeBSD 5.X or later) which will
>>snapshot the filesystem 
>>first.  Either that, or do what we had to do for
>>years and drop down to 
>>single-user mode and make sure no processes are
>>running to change the 
>>filesystem.  Dump needs the filesystem to be static.
>>
>>Then when you restore you will get precisely *one*
>>similar "error" (at 
>>least on 5.4), which I can't explain but can say
>>*does not matter*.  I 
>>have restored several such dumps and compared them
>>to the original 
>>filesystem and they are fine.  You should do that
>>yourself for your own 
>>peace of mind.  (I do similar to you but with gzip
>>and on 5.4).
>>
>>The "error" you'll get should be:
>>
>>     expected next file <inumber>, got <inumber>
>>             A file that was not listed in the
>>directory showed up.  
>>This can
>>             occur when using a dump created on an
>>active file system.
>>
>>and I think it must be some artefact of the
>>snapshot/dump interaction.
>>
>>If you use -L and *still* have trouble then it
>>sounds like a bug.
>>
>>--Alex
>>
>>
>>
>>
>>    
>>
>
>I wasn't aware booting off the cd and running fixit
>made my filesystems become live...
>  
>
It shouldn't, but why are you doing that?  Run dump with -L while your 
laptop is up and running FreeBSD.

But while you are in your fixit CD or single-user you could try fscking 
the filesystems just in case.  The output you showed certainly looks 
like files disappeared between the "dumping directories" and "dumping 
files" pass.  I think that a corrupted filesystem could show that 
behaviour.  Whereas the "error" I consistently get looks like an extra 
file somehow *appeared* between the passes.

>dump -0 -C 32 -f - |bzip2 --best | dd of=/foo/bar.dbz2
>  
>
won't "bzip2 --best > /foo/bar.dbz2" do?  Why dd?  You might also want 
-a in the dump command so that there are no "tape size" calculations (or 
maybe that's the default in 6.X, you'd have to check the man page).

Btw, restore also has a -N option which does the restore without 
actually writing any data.  God for seeing if a restore would work but 
quicker and doesn't require any disk space :-)

--Alex





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