Hi,

Is it possible to clarify what resides behind the concept of levels regarding 
dump(8) ?
For me the level 0 is understood to be a complete dump of all files on at a 
given mount point and all subdirectories. But I can't figure out what upper 
levels are.

Regards

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A level 0 dumps includes all files. A level n dump are all the files
that have changed or were added since the last level n - 1 dump. 

	-Otto

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My dump level 1 dumps all the files again. How to let it dump based on the
lower level ?

I did as follows :
sudo dump -0ua -f /mnt/tera/backup/2010.02.18_www.0 /var/www/htdocs/
sudo dump -0ua -f /mnt/tera/backup/2010.02.18_www.1 /var/www/htdocs/

Regards

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On Thu, Feb 18, 2010 at 11:21 PM, Jean-Francois <jfsimon1981@gmail.com> wrote:


You did two level 0 dumps, so what else you expect ?;)

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Mistyped the mail. I proceed in this way and get two times the same dump. Is
it normal ?
sudo dump -0ua -f /mnt/tera/backup/2010.02.18_www.0 /var/www/htdocs/
sudo dump -1ua -f /mnt/tera/backup/2010.02.18_www.1 /var/www/htdocs/

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Show your dump output. Of both runs.

	-Otto

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Not sure to understand the subtle of the man page explanations regarding the
dump of different nature of mount points.

Just one additional information, the dump of higher levels work when I dump
/var but not /var/htdocs.

$ sudo dump -0ua -f /mnt/tera/backup/2010.02.18_www.0 /var/www/htdocs/
  DUMP: Ignoring u flag for subdir dump
  DUMP: Dumping sub files/directories from /var
  DUMP: Dumping file/directory /var/www/htdocs/
  DUMP: Date of this level 0 dump: Fri Feb 19 21:47:18 2010
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/rwd0g (/var) to /mnt/tera/backup/2010.02.18_www.0
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 188530 tape blocks.
  DUMP: Volume 1 started at: Fri Feb 19 21:47:21 2010
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 196284 tape blocks on 1 volume
  DUMP: Date of this level 0 dump: Fri Feb 19 21:47:18 2010
  DUMP: Volume 1 completed at: Fri Feb 19 21:47:33 2010
  DUMP: Volume 1 took 0:00:12
  DUMP: Volume 1 transfer rate: 16357 KB/s
  DUMP: Date this dump completed:  Fri Feb 19 21:47:33 2010
  DUMP: Average transfer rate: 16357 KB/s
  DUMP: Closing /mnt/tera/backup/2010.02.18_www.0
  DUMP: DUMP IS DONE
$ sudo dump -1ua -f /mnt/tera/backup/2010.02.18_www.1 /var/www/htdocs/
  DUMP: Ignoring u flag for subdir dump
  DUMP: Subdir dump is done at level 0
  DUMP: Dumping sub files/directories from /var
  DUMP: Dumping file/directory /var/www/htdocs/
  DUMP: Date of this level 0 dump: Fri Feb 19 21:47:36 2010
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/rwd0g (/var) to /mnt/tera/backup/2010.02.18_www.1
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 188530 tape blocks.
  DUMP: Volume 1 started at: Fri Feb 19 21:47:39 2010
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 196284 tape blocks on 1 volume
  DUMP: Date of ...
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There you go.

Incremental dumps should be done at the filessytem level. 


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On Fri, Feb 19, 2010 at 12:49 PM, Jean-Francois <jfsimon1981@gmail.com> wrote:

The key is the last sentence of this paragraph from the dump(8) manpage:
     files-to-dump is either a mountpoint of a filesystem or a list of files
     and directories on a single filesystem to be backed up as a subset of the
     filesystem.  In the former case, either the path to a mounted filesystem
     or the device of an unmounted filesystem can be used.  In the latter
     case, certain restrictions are placed on the backup: -u is ignored, the
     only dump level that is supported is -0, and all of the files must reside
     on the same filesystem.

So, if you're not dumping an entire filesystem, then you always get a
full (level 0) dump.

(Why?  At least part of the reason is that if you're not doing the
full filesystem, inode ctime isn't sufficient to determine whether a
file would be new to the dump.)


Philip Guenther

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Is it possible to clarify further this particular para of dump(8), I cant
understand the differences that are explained here between the nature of the
mount points and file systems and the relationship to what is prohibited (L+1
dumps are).

Thanks.
Regards

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You are doing two level 0 dumps. The seconds invication should use -1ua
Also, note that these dumps are filesystem dumps. A whole filesystem
is dumped this way.


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Are all dump levels packed into the same one file like I seem to understand ?

As far as I am concerned I dump in this way :
dump  -0u -f /mnt/backup/backup /mnt/donnees/
dump  -1u -f /mnt/backup/backup /mnt/donnees/
...

This is correct, is'nt it ?
Regards.

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That's incorrect.

In your first command you do a full backup of /mnt/donnees
and save it to the file /mnt/backup/backup.

With your second command you do an incremental backup which saves
only the changed files between the first backup and now. You save it
on the same file which means that you overwrite/delete the first backup.

If you wanted to restore something you would be able to restore
only the changed files between first and second backup. You need
to have both files (stored separately) to do full -current (tm)
restore of your files.

If you wander why to use different dump levels the answer is for
organizing the backup policy and saving a hell lot of space/tapes
than doing always full backups.

regards,

Giannis

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from dump(8)'s man page:

     -0-9    Dump levels.  A level 0, full backup, guarantees the entire file
             system is copied (but see also the -h option below).  A level
             number above 0, incremental backup, tells dump to copy all files
             new or modified since the last dump of a lower level.  The de-
             fault level is 0.

So a dump of level 0 is a complete dump, a dump of level 1 is a dump of all
files since last dump 0, a dump of level 2 is a dump of all files since last
dump of level 1, and so on

Gilles

-- 
Gilles Chehade
freelance developer/sysadmin/consultant

		   http://www.poolp.org

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Dump levels other than 0 allow you to make partial dumps.

I used to do dump level 0's at the start of the month.

Then from Monday to Thursday I'd to dump 9's.  Each dump
would save things from the previous 9 (or 0 the first time).
Friday's I'd do a level 8.

Thus each M-T I'd save the days work, Friday I'd save the
weeks work.  Then at the start of the next month a level 0
dump would make a copy of everything.

Each dump level going downwards saves all the data from
previous (higher) numbered dumps.

--STeve Andre'

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Just to confirm or unconfuse myself if you're doing dump 9s on Monday to
Thursday aren't you getting everything from the previous days each dump
rather than just the day before?  I thought to get just the files changed on
a particular day you'd have to go:

Mon  - dump 5
Tues  - dump 6
Wed  - dump 7
Thurs - dump 8
Fri     - dump 4

-- 

Dethink to survive - Mclusky

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A dump at level N includes everything modified since the last dump
at N-1 or lower.

Thus, for example, if on Monday we do a level 0 dump of /foo, and then
on Tuesday, we do a level 1 dump of /foo, that second dump will contain
everything that's changed in the last day.

If on Wednesday, we do a level 3 dump of /foo (note that I skipped level
2 on purpose) then we will have everything that changed since Tuesday,
since 3 > 1.

If on Thursday, we NOW do a level 2 dump of /foo, we will have everything
that changed since the level 1 on Tuesday -- two days' worth of changes.

This all works as planned provided you give "u" flag to dump, which
instructs it keep track (in /etc/dumpdates) of which filesystems it
has dumped and when.  Note (a) that filesystems are tracked by device,
so that if you umount /foo and remount it as /bar, the right thing
happens and (b) the timestamp used is the time that the dump BEGINS,
but it is not written into the file until the dump ENDS.  (This is
part of the set of mechanisms which deal with changes that take place
while dump is running.)

Dump's various levels provide a lot of ways to minimize one or more
of (1) dump run time (2) dump output size (3) number of dumps required
to restore a failed filesystem.  For example, if you did level 0 dumps
every day, you would maximize (1) and (2) but minimize (3), since it would
always be 1.  For another example, if you did level 0 dumps on Sunday
and 1-6 Monday-Saturday, then you would cut down (1) and (2) considerably
six days a week, but you might need to restore as many as 7 dumps
which means you've pushed (3) fairly high.  So choosing which scheme
is appropriate for you requires having knowledge of your environment
and answering questions like:

	- how much backup space do you have?
	- do you lose entire disks often?
	- do your users screw up and require restores often?
	- do you have an open or limited backup window?
	- what are you backing up?
	- does the data you're backup up compress ...
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