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Date:      Sat, 21 Nov 2009 15:33:01 +0100
From:      Bernt Hansson <bernt@bah.homeip.net>
To:        George Davidovich <freebsd@optimis.net>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Dump
Message-ID:  <4B07FA1D.4090302@bah.homeip.net>
In-Reply-To: <20091121095251.GA63630@marvin.optimis.net>
References:  <4B0562A4.5050405@bah.homeip.net>	<4B056636.6050309@infracaninophile.co.uk>	<4B075AAA.80205@bah.homeip.net> <20091121095251.GA63630@marvin.optimis.net>

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George Davidovich said the following on 2009-11-21 10:52:
> On Sat, Nov 21, 2009 at 04:12:42AM +0100, Bernt Hansson wrote:
>> Matthew Seaman skrev:
>>> Bernt Hansson wrote:
>>>> I've been testing backups with dump, works well BUT
>>>> -L does not work. For example
>>>>
>>>> dump -0 -a -u -L -f /mnt/dump.home.full /dev/ad0s2d
>>> I believe that you need to tell dump the mount point of the file
>>> system in order for it to create a snapshot, rather than the device
>>> file for the partition. (ie. snapshotting only makes sense on a
>>> mounted read-write filesystem).
> 
> Actually, the above isn't correct.  A device special is fine.  From the
> dump(8) manpage:
>   
>   The file system to be dumped is specified by the argument filesystem
>   as either its device-special file or its mount point (if that is in a
>   standard entry in /etc/fstab).
> 
> The criteria unique to live dumps is that /dev/ad0s2d must be already
> mounted, and there must be a .snap directory in its root.  You've since
> changed your command, so I won't address what the problem might have
> been.
> 
>>> Also, if you're dumping a snapshotted FS to a local file, then bump
>>> up the cachesize to improve performance a lot.  Add '-C 32' to your
>>> command-line.
>> Ok. I've tested this
>> dump -1 -a -u -L -C 64 -h 0 -f /usr/home/bernt/disk2/dump.backup.home.2 /usr/home
> 
> Was the change from 'dump -0' to 'dump -1' intentional?

Yes.

> Dump levels are
> rarely chosen to be sequential, but a level of 1 or greater is generally
> performed after a level 0 dump.

Yes. I've done a level 0 dump.

>> The error is mksnap_ffs: Cannot create /usr/home/.snap/dump_snapshot:
>> Invalid argument dump: Cannot create /usr/home/.snap/dump_snapshot: No
>> such file or directory

The directory exist.
drwxrwx---   2 root   operator   512 16 Nov 19:19 .snap

> You've now specified what's likely a directory (/usr/home), not a
> device-special or mount point.  Your choices of valid filesystems can be
> determined by running df(1) and examining the first and last columns.
> On a typical install those two columns might be:
> 
>   Filesystem      Mounted on
>   /dev/ad0s1a     /
>   devfs           /dev         # ignore this line
>   /dev/ad0s1e     /tmp
>   /dev/ad0s1f     /usr
>   /dev/ad0s1d     /var
> 
> Pick one.  I prefer device names.

This is from my original post
dump -0 -a -u -L -f /mnt/dump.home.full /dev/ad0s2d
ad0s2d is /usr/home

> FWIW, if you're going to be using dump regularly (i.e. multiple dump
> levels and/or multiple hosts) and dumping to files, I'd suggest a naming
> convention of
> 
>

I am going to use it on a regular basis, at least that is my intention.
If I can get the -L flag to work

> hostname-20090405-usr-0

I see what you mean. But since I already have a script (tar) that takes 
care of that.

> to save you the grief of date fragility, and give you a meaningful
> display in 'ls -l' when restoring.  So, for a level 0 dump on your
> system, your commands might be:
> 
>   dumpdir=/home/bernt/disk2
>   dump -0auL -C 64 -f $dumpdir/hostname-20091121-root-0 -h 0 /
>   dump -0auL -C 64 -f $dumpdir/hostname-20091121-usr-0  -h 0 /usr
>   dump -0auL -C 64 -f $dumpdir/hostname-20091121-var-0  -h 0 /var
> 



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