Re: [BackupPC-users] How to delete backups

[backuppc]

Holger Parplies wrote at about 01:46:03 +0100 on Thursday, December 11, 2014:
 > Hi,
 > 
 > Timothy J Massey wrote on 2014-12-10 11:53:38 -0500 [Re: [BackupPC-users] 
 > How to delete backups]:
 > > Holger Parplies  wrote on 12/10/2014 10:59:17 AM:
 > > > [...]
 > > > ***Never*** run BackupPC_nightly from the command line. ***Never*** 
 > > > advise
 > > > other to do so.
 > > > Really quite simple.
 > > 
 > > Why not, exactly?  I do it all the time.  I'm not saying you're wrong:  I 
 > > just want to know where the harm might be.  But you state the "never do 
 > > that" in such strong terms, I'm wondering where the disconnect it.
 > 
 > BackupPC_link and BackupPC_nightly shouldn't run concurrently because of
 > race conditions in the code. As far as I remember, BackupPC_nightly might
 > remove (or chain-renumber) a file BackupPC_link is about to create a link
 > to, which would result in the file missing from the backup or containing
 > incorrect data. The odds of this happening might not be high, but why take
 > the risk? There might be further problems I am unaware of. 

I believe you nailed it.

BackupPC is constructed so that only BackupPC_nightly and
BackupPC_link change pool entries by adding/deleting/renumbering chain
entries. Hence, the scheduler only needs to make sure that
BackupPC_nightly and BackupPC_link don't runs simultaneously... though
of course as you pointed out the risk on any given run is rather
small...

Note the second rsync run may change the content of an existing pool
entry by adding the rsync checksums but that doesn't create a conflict
since the name and actual uncompressed content of the pool entry
doesn't change.


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Re: [BackupPC-users] How to delete backups

[Holger Parplies]

Hi,

Timothy J Massey wrote on 2014-12-10 11:53:38 -0500 [Re: [BackupPC-users] How 
to delete backups]:
> Holger Parplies  wrote on 12/10/2014 10:59:17 AM:
> > [...]
> > ***Never*** run BackupPC_nightly from the command line. ***Never*** advise
> > other to do so.
> > Really quite simple.
> 
> Why not, exactly?  I do it all the time.  I'm not saying you're wrong:  I 
> just want to know where the harm might be.  But you state the "never do 
> that" in such strong terms, I'm wondering where the disconnect it.

BackupPC_link and BackupPC_nightly shouldn't run concurrently because of
race conditions in the code. As far as I remember, BackupPC_nightly might
remove (or chain-renumber) a file BackupPC_link is about to create a link
to, which would result in the file missing from the backup or containing
incorrect data. The odds of this happening might not be high, but why take
the risk? There might be further problems I am unaware of. If you let the
scheduler run BackupPC_nightly, it will take care not to run BackupPC_link
concurrently, so possible problems will be avoided. It will also receive
the statistical output from BackupPC_nightly, which, I believe, it won't
if you run BackupPC_nightly from the command line.

> [...]
> By the way, that's probably the best way to handle this problem.  Set the 
> FullKeepCnt and IncKeepCnt to 1, do a full backup and let BackupPC manage 
> deleting everything for you!  :)

I agree with that (except that it's "IncrKeepCnt" ;-) in that it is the
easiest and least error-prone way. This will leave you with one backup though,
so it's mostly equivalent to the "delete entire host" case (you have the
choice of running a backup after deleting the host depending on what you want)
except for backup numbering (deleting the host will restart at 0). If you want
to keep the last 10 backups, for instance, you would need to count your fulls
and incrementals and adjust the KeepCnts to match.

Regards,
Holger

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Re: [BackupPC-users] How to delete backups

[Holger Parplies]

Hi,

Colin Shorts wrote on 2014-12-10 16:30:40 + [Re: [BackupPC-users] How to 
delete backups]:
> On 10/12/14 15:59, Holger Parplies wrote:
> > Colin Shorts wrote on 2014-12-10 11:45:41 +0000 [Re: [BackupPC-users] How 
> > to delete backups]:
> >> You might want to press  before typing
> >> `/usr/share/BackupPC/bin/BackupPC_nightly 0 255', otherwise it will get
> >> deleted too.
> > right, press  *before* the command, *not after*. ***Never*** run
> > BackupPC_nightly from the command line. ***Never*** advise other to do so.
> > Really quite simple.
> >
> I was just trying to point out that the commands provided would have 
> deleted BackupPC_nightly ;)

yes, and I agree with you there. I strongly disagree with the previous
poster's intended advice, though.

> On 10/12/14 11:41, Stephen Mew wrote:
> ~snip~
>  > rm -fR  /usr/share/BackupPC/bin/BackupPC_nightly 0 255
> ~snip~
> 
> That wouldn't be good, would it?

I'm tempted to say that it would be better than running the command, but the
comparison is really pointless. Of two things you should simply refrain from
doing, who cares which one would be more harmful?

> But as you say, there is no real reason to run the command as cron 
> should take care of it soon enough -

Actually, it's not cron, it's the BackupPC daemon, and this is the whole
point: the daemon needs to have control over when the command is run(ning).

> unless you were deleting a backup to gain disk space urgently ;)

Exactly, and this did not seem to be the case here. And again: even in this
case, you don't run the command manually, you let the daemon run it. It will
do so right away if it is safe, so there's no penalty. If it is *not* safe,
you don't want to override the safeguard.

Regards,
Holger

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Re: [BackupPC-users] How to delete backups

[Timothy J Massey]

Holger Parplies  wrote on 12/10/2014 10:59:17 AM:

> Colin Shorts wrote on 2014-12-10 11:45:41 +0000 [Re: [BackupPC-
> users] How to delete backups]:
> > You might want to press  before typing 
> > `/usr/share/BackupPC/bin/BackupPC_nightly 0 255', otherwise it will 
get 
> > deleted too.
> 
> right, press  *before* the command, *not after*. ***Never*** run
> BackupPC_nightly from the command line. ***Never*** advise other to do 
so.
> Really quite simple.

Why not, exactly?  I do it all the time.  I'm not saying you're wrong:  I 
just want to know where the harm might be.  But you state the "never do 
that" in such strong terms, I'm wondering where the disconnect it.

For the original poster:  The only time I need to manually delete a backup 
is when I need the space, and I need it *right* *now*.  Otherwise I would 
simply change the FullKeepCnt and IncKeepCnt variables and let BPC clean 
it up for me.  (Or where I do a backup at the wrong time and it catches a 
large amount of unimportant temporary files *and* I really need the space 
and I don't want to lose my history, but that's a very, very specific case 
that doesn't happen enough to make this a general practice.)

By the way, that's probably the best way to handle this problem.  Set the 
FullKeepCnt and IncKeepCnt to 1, do a full backup and let BackupPC manage 
deleting everything for you!  :)

(Also, for completeness, if you delete a single backup, you better know 
what you're doing, particularly which backups depend on the backup you're 
deleting.  Or, if you have filled-in backups (like I do), why deleting 
that full doesn't actually free up any space, even *after* running 
nightly...  And don't forget to modify the backups file to match the 
destruction you are doing...  If all of that sounds like too much, simply 
use the FullKeepCnt and IncKeepCnt and let BPC do the cleanup.)

Tim Massey
 
Out of the Box Solutions, Inc. 
Creative IT Solutions Made Simple!
http://www.OutOfTheBoxSolutions.com
tmas...@obscorp.com 
 
22108 Harper Ave.
St. Clair Shores, MI 48080
Office: (800)750-4OBS (4627)
Cell: (586)945-8796 
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Re: [BackupPC-users] How to delete backups

[Colin Shorts]

On 10/12/14 15:59, Holger Parplies wrote:
> Hi,
>
> Colin Shorts wrote on 2014-12-10 11:45:41 +0000 [Re: [BackupPC-users] How to 
> delete backups]:
>> You might want to press  before typing
>> `/usr/share/BackupPC/bin/BackupPC_nightly 0 255', otherwise it will get
>> deleted too.
> right, press  *before* the command, *not after*. ***Never*** run
> BackupPC_nightly from the command line. ***Never*** advise other to do so.
> Really quite simple.
>
I was just trying to point out that the commands provided would have 
deleted BackupPC_nightly ;)

On 10/12/14 11:41, Stephen Mew wrote:
~snip~
 > rm -fR  /usr/share/BackupPC/bin/BackupPC_nightly 0 255
~snip~

That wouldn't be good, would it?

But as you say, there is no real reason to run the command as cron 
should take care of it soon enough - unless you were deleting a backup 
to gain disk space urgently ;)

Cheers,
Colin

-- 
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c.sho...@intrallect.com
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137A George Street, Edinburgh, EH2 4JY, Scotland
Intrallect is part of the Leading Software Group


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Re: [BackupPC-users] How to delete backups

[Holger Parplies]

Hi,

Colin Shorts wrote on 2014-12-10 11:45:41 + [Re: [BackupPC-users] How to 
delete backups]:
> You might want to press  before typing 
> `/usr/share/BackupPC/bin/BackupPC_nightly 0 255', otherwise it will get 
> deleted too.

right, press  *before* the command, *not after*. ***Never*** run
BackupPC_nightly from the command line. ***Never*** advise other to do so.
Really quite simple.


Before that, on 10/12/14 11:41, Stephen Mew had written:
> >Solution
> >
> >
> >cd /var/lib/BackupPC/pc//
> >ls
> >rm -fR  [...]

Yes, it's a solution. The question remains, for what problem. If you know
*exactly* what you're doing, you can try that. Chances are, if you're asking
here how to delete backups, you *don't* know *exactly* what you're doing. If
you're recommending this, you probably also don't *exactly* know what you're
doing, otherwise you wouldn't recommend it. Removing one backup directory will
usually work quite well, if and only if no backups depend on it. Nothing will
prevent you from removing data still needed by other backups with 'rm'. Don't
expect BackupPC to handle the resultant pc directory gracefully.

If you want to remove *all* backups of one client (the original question
suggests this might be the case),

rm -rf /var/lib/BackupPC/pc/

will work (supposing /var/lib/BackupPC is your TopDir ... mine is different).
No dependency problems, no summary files to patch. For removing single backups,
get Jeffrey's script.

> >nano /var/lib/BackupPC/pc//backups

nano? The only thing you need to know about nano is Ctrl-x. Tip for Debian
users:

update-alternative --set editor /usr/bin/nvi
update-alternative --set view /usr/bin/nview

But that's kind of off-topic (and a matter of opinion - I'm sure there are
other vi clones that are rather acceptable ;-).

Yet earlier still, on 10 December 2014 at 11:04, 
lanceh1412-busin...@yahoo.co.uk <mailto:lanceh1412-busin...@yahoo.co.uk> had 
written:
> >How do you delete backups? I've been messing around with lots of
> >different hosts trying to work out how to use the software and I
> >want to get rid of all the unwanted backups.

If you want to get rid of all backups of one or more hosts, delete the host
directories (or move them to $TopDir/trash and BackupPC will do it for you).

> >[...]
> >There is no BackupPC_delete whch I have seen mentioned in the
> >archive.

That's correct. It's not part of the official BackupPC software, it's a user
contribution by Jeffrey J. Kosowsky. I don't have a recent copy, but I'm sure
Jeffrey does ;-).


Let me state this clearly:

After deleting backups, there is no *need* to initiate a BackupPC_nightly run.
BackupPC will automatically do that at some configured point within the next
24 hours. Only if you absolutely want to see the space freed as soon as
possible do you need to politely ask BackupPC to run the command as soon as it
is safe to do so:

# su backuppc -c "/usr/share/backuppc/bin/BackupPC_serverMesg 
BackupPC_nightly run"


Hope that helps.

Regards,
Holger

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Re: [BackupPC-users] How to delete backups

[Colin Shorts]

You might want to press  before typing 
`/usr/share/BackupPC/bin/BackupPC_nightly 0 255', otherwise it will get 
deleted too.


-C

On 10/12/14 11:41, Stephen Mew wrote:


BackupPC does not as far as I know have scripts or commands yet to 
actually remove backup from the pool.


To remove bckups you need to get into the script.


Solution


cd /var/lib/BackupPC/pc//
ls
rm -fR  /usr/share/BackupPC/bin/BackupPC_nightly 0 255


Check space reclaimed with df.

You still need to remove a statistic line, otherwise you will see it 
in your web interface. To do that:



nano /var/lib/BackupPC/pc//backups
With ctrl+k you can remove the line with 


done..



On 10 December 2014 at 11:04, lanceh1412-busin...@yahoo.co.uk 
 
> wrote:


Hi,

How do you delete backups? I've been messing around with lots of
different hosts trying to work out how to use the software and I
want to get rid of all the unwanted backups.

My bin has the following scripts

BackupPC   BackupPC_fixupBackupSummary  BackupPC_tarCreate
BackupPC_archive   BackupPC_link  BackupPC_tarExtract
BackupPC_archiveHost   BackupPC_nightly BackupPC_tarPCCopy
BackupPC_archiveStart  BackupPC_restore
BackupPC_trashClean

BackupPC_attribPrint   BackupPC_sendEmail   BackupPC_zcat
BackupPC_dump  BackupPC_serverMesg  BackupPC_zipCreate

There is no BackupPC_delete whch I have seen mentioned in the
archive. I'm using version 3.2.1 on Ubuntu 14.04


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Re: [BackupPC-users] How to delete backups

[Stephen Mew]

BackupPC does not as far as I know have scripts or commands yet to actually
remove backup from the pool.

To remove bckups you need to get into the script.


Solution

cd /var/lib/BackupPC/pc//
ls
rm -fR  /usr/share/BackupPC/bin/BackupPC_nightly 0 255

Check space reclaimed with df.

You still need to remove a statistic line, otherwise you will see it in
your web interface. To do that:

nano /var/lib/BackupPC/pc//backups
With ctrl+k you can remove the line with 


done..


On 10 December 2014 at 11:04, lanceh1412-busin...@yahoo.co.uk <
lanceh1412-busin...@yahoo.co.uk> wrote:

> Hi,
>
> How do you delete backups? I've been messing around with lots of different
> hosts trying to work out how to use the software and I want to get rid of
> all the unwanted backups.
>
> My bin has the following scripts
>
> BackupPC   BackupPC_fixupBackupSummary  BackupPC_tarCreate
> BackupPC_archive   BackupPC_linkBackupPC_tarExtract
> BackupPC_archiveHost   BackupPC_nightly BackupPC_tarPCCopy
> BackupPC_archiveStart  BackupPC_restore BackupPC_trashClean
> BackupPC_attribPrint   BackupPC_sendEmail   BackupPC_zcat
> BackupPC_dump  BackupPC_serverMesg  BackupPC_zipCreate
>
> There is no BackupPC_delete whch I have seen mentioned in the archive. I'm
> using version 3.2.1 on Ubuntu 14.04
>
>
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>
>


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Re: [BackupPC-users] How to delete backups

[Ibon Castilla]

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1

Hi there,

Please, fix my words if I'm wrong :)

On version 3 I think there is no binary to achieve what you want. I
have founded this link with a simple procedure to do it manually:
http://blackbird.si/deleting-backup-from-backuppc-manually/

Hope this helps you :)

Abrazo, Ibon.

Usa Software Libre, tus úlceras te lo agradecerán
Realizado con Software Libre.
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Finderprint: 1761 59B9 6DE6 0402 31B9 1872 178F A6FD 75F9 EB29

El 10/12/14 a las 12:04, lanceh1412-busin...@yahoo.co.uk escribió:
> Hi,
> 
> How do you delete backups? I've been messing around with lots of 
> different hosts trying to work out how to use the software and I
> want to get rid of all the unwanted backups.
> 
> My bin has the following scripts
> 
> BackupPC   BackupPC_fixupBackupSummary
> BackupPC_tarCreate BackupPC_archive   BackupPC_link
> BackupPC_tarExtract BackupPC_archiveHost   BackupPC_nightly
> BackupPC_tarPCCopy BackupPC_archiveStart  BackupPC_restore
> BackupPC_trashClean BackupPC_attribPrint   BackupPC_sendEmail
> BackupPC_zcat BackupPC_dump  BackupPC_serverMesg
> BackupPC_zipCreate
> 
> There is no BackupPC_delete whch I have seen mentioned in the
> archive. I'm using version 3.2.1 on Ubuntu 14.04
> 
> 
> --
>
> 
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
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>
> 
> 
> 
> ___ BackupPC-users
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Version: GnuPG v1.4.11 (GNU/Linux)

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2MUAoLjD7dXEVoUW1+qWWZf/LO8q6CnU
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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Jeffrey J. Kosowsky]

Thomas Birnthaler wrote at about 11:29:27 +0100 on Friday, January 9, 2009:
 > A lot of thank to everybody which answered my questions
 > which have been asked a lot of times, sorry :-(.
 > 
 > I've learned from your answers that my model of BackupPC storage of full and 
 > incremental backups was too weak and that it's too dangerous to delete 
 > backups by hand. So we won't do that.
 > 
 > The script http://backuppc.wiki.sourceforge.net/How+to+delete+backups for 
 > deleting you mentioned I already found. But it deleted full + all dependant 
 > incremental backups which wasn't what we wanted.
 > 
 > Some wanted to know, what were the reasons for my question. So here we are:
 > 
 > 1. Problem: Accidential backup of huge files and directories (e.g. 
 > DVD-Images, 
 > backups done by a second tool we haven't been told) because some users do 
 > things they shouldn't do. These fill up the BackupPC backup-Space and it 
 > doesn't make any sense to keep them. In one case we reached the limit of 95% 
 > and BackupPC didn't do any backups then (which is a good behaviour!).
 > 
 > True, this is a configuration problem! But if you detect it after the backup 
 > happened, how do you free the space then? My solution was to set the file 
 > size to zero by hand, but keep all the hardlinks. This is manageable for 
 > some 
 > files, but not very easy for 100 or more.
 > 
I have written a program that allows you to delete individual files
from 1 or more incremental or full backups -- it properly takes care
of all the inheritance from level n to level n+1 etc. incremental
backups. This should allow you to transparently delete just the
offending files or directories/

The program has been posted to the mailing list -- it's called
BackupPC_deleteFiles.pl

It was written for exactly the scenario you envisioned -- mistaken
backups of large files -- and it allows you to delete those without
eliminating the entire backup (which would seem to me to be foolishly
throwing out the baby with the bathwater).

 > 2. Problem: Incremental backups take much longer time than full backups 
 > (weekly full and daily incremental) on two of the networks we manage.
 > 
 > Some answered that this should not happen. But some answered that this could 
 > happen depending on machine, memory, network and so on. So no real answer to 
 > that, we have to investigate it further. If we find a reason for that 
 > problem, I will post it.
 > 
I didn't see anyone confirming that the multi-X slowdown for
incrementals vs. fulls is possible. At most, I saw someone saying that
in certain circumstances an incremental could take as long as a
full. (I'm just summarizing what I believe I saw in the thread unless
you have had personal communications otherwise).

 > Again, answers from all of you were very helpful!
 > 
 > Thomas Birnthaler
 > -- 
 > OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
 > tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
 > Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
 > Thomas Birnthaler / +49 171-3047465 / t...@ostc.de / pgp 0xFEE7EB4C
 > Hermann Gottschalk / +49 173-3600680 / h...@ostc.de / pgp 0x0B2D8EEA
 > 
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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Thomas Birnthaler]

A lot of thank to everybody which answered my questions
which have been asked a lot of times, sorry :-(.

I've learned from your answers that my model of BackupPC storage of full and 
incremental backups was too weak and that it's too dangerous to delete 
backups by hand. So we won't do that.

The script http://backuppc.wiki.sourceforge.net/How+to+delete+backups for 
deleting you mentioned I already found. But it deleted full + all dependant 
incremental backups which wasn't what we wanted.

Some wanted to know, what were the reasons for my question. So here we are:

1. Problem: Accidential backup of huge files and directories (e.g. DVD-Images, 
backups done by a second tool we haven't been told) because some users do 
things they shouldn't do. These fill up the BackupPC backup-Space and it 
doesn't make any sense to keep them. In one case we reached the limit of 95% 
and BackupPC didn't do any backups then (which is a good behaviour!).

True, this is a configuration problem! But if you detect it after the backup 
happened, how do you free the space then? My solution was to set the file 
size to zero by hand, but keep all the hardlinks. This is manageable for some 
files, but not very easy for 100 or more.

2. Problem: Incremental backups take much longer time than full backups 
(weekly full and daily incremental) on two of the networks we manage.

Some answered that this should not happen. But some answered that this could 
happen depending on machine, memory, network and so on. So no real answer to 
that, we have to investigate it further. If we find a reason for that 
problem, I will post it.

Again, answers from all of you were very helpful!

Thomas Birnthaler
-- 
OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
Thomas Birnthaler / +49 171-3047465 / t...@ostc.de / pgp 0xFEE7EB4C
Hermann Gottschalk / +49 173-3600680 / h...@ostc.de / pgp 0x0B2D8EEA

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Jeffrey J. Kosowsky]

Thomas Birnthaler wrote at about 00:41:26 +0100 on Friday, January 9, 2009:
 > Wow Tino,
 > 
 > your faster anwering than I'm able to question ;-)
 > 
 > > Your web view would become inconsistent (e.g. deleted files becoming
 > > visible again).
 > Ok, this seems to be a case we forgot ;-(
 > But if this doesn't matter to us, is it then okay to delete any backup?
You also have the problem that you are missing new changes so that you
will have an inconsistent system state.
 > Do the GUI and the creation of new backups work and don't throw errors?
 > 
 > By the way: How are deleted files represented?
They are given a type=10 deleted attribute in the corresponding
directory attrib file.
 > I argue they are just missing in the respective backup hardlink
 tree.
That would be wrong -- you need to explicitly notate that files are
deleted because otherwise the absence of a file is interpreted to mean
that you inherit the file from earlier versions.
 > So if you delete the backup hardlink tree, the "holes" disappear?
Nope -- see above.
 > 
 > > > In both cases only changed/new files use disk space according to the
 > > > hardlink concept of BackupPC.
 > >
 > > Yes. Fulls need some more space because they are completely filled, that
 > > is, all directories contain hardlinks to all the files, whereas
 > > incrementals only contain hardlinks to new and changed files -
 > > filesystem-wise they've got holes which are filled by the CGI.
 > But this is just management space (directories and their dentries) --- which 
 > uses of course some inode and data space. No additional data space and inode 
 > space is needed for the real files in full backups compared to a incremental 
 > backup. Is that correct?
Nope. Zero length files are given their own inodes. Also symbolic links are
represented as files (which are non-zero length). Now this might not
make a measurable difference but it is important to understand
what BackupPC is doing before you generalize or make assumptions.

 > 
 > If this is the case we think about doing full backups all the time.
 > So deletion of backups is ok then too.
 > 
 > > > We have also detected, that in some cases incremental backups need much
 > > > more time than full backups (factor 3-5) This sounds odd to us.
 > >
 > > What transfer method are you using?
 > rsync over GBit networks between Linux machines and also between MacOS 
 > machines. In both cases that effect happens.
 > 
 > Thomas Birnthaler
 > -- 
 > OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
 > tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
 > Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
 > Thomas Birnthaler / +49 171-3047465 / t...@ostc.de / pgp 0xFEE7EB4C
 > Hermann Gottschalk / +49 173-3600680 / h...@ostc.de / pgp 0x0B2D8EEA
 > 
 > --
 > Check out the new SourceForge.net Marketplace.
 > It is the best place to buy or sell services for
 > just about anything Open Source.
 > http://p.sf.net/sfu/Xq1LFB
 > ___
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 > BackupPC-users@lists.sourceforge.net
 > List:https://lists.sourceforge.net/lists/listinfo/backuppc-users
 > Wiki:http://backuppc.wiki.sourceforge.net
 > Project: http://backuppc.sourceforge.net/
 > 

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Jeffrey J. Kosowsky]

Thomas Birnthaler wrote at about 00:00:53 +0100 on Friday, January 9, 2009:
 > Hello,
 > 
 > we are using BackupPC and it works perfect on different places.
 > But we have 2 questions on it:
 > 
 > 1. We wonder why neither the GUI nor the commands offer a possibility to 
 > delete backups (full and incremental). If e.g. the backup partition is 
 > filled 

Someone has written a bash routine called I think
BackupPC_deleteBackup (see:
http://backuppc.wiki.sourceforge.net/How+to+delete+backups) that
allows you to delete individual backups -- either full or incremental
-- along with any dependent higher level incremental backups. It is
necessary to also delete the dependent backups or else they are no
longer accurate as-is (note the program I wrote BackupPC_deleteFiles
goes through a *lot* of painful chains and cases to allow you to
delete individual files from individual backups but it would be very
slow to extend this to an entire backup).

 > up, this would be very helpful.
 > 
 > As far as we understood the concept of using hardlinks and different 
 > directories for each backup + a hash pool for each file it seems to be very 
 > easy to delete a backup NN.
 > 
 > Just delete recursively the backup directory NN and the nightly run will 
 > really destroy all orphaned files with a hardlink count of 1.
 > 
You need to also delete the higher level incremental backups or they
will be wrong/meaningless. Also you probably want to adjust the backup
info file -- this is done correctly by the program I reference above.

 > If a full backup is deleted that way, incremental backups depending on it 
 > then 
 > depend on the next earlyer full backup and work as before. Same is true for 
 > incremental backups. So the GUI works as before and the creation of new 
 > backups too.
 > 
 > Is that idea correct?
NOPE - incremental backups by definition are meaningless/invalid if
you delete lower level full or incremental backups on which they depend.
 > 
 > 2. What is real benefit of incremental backups compared to full backups?
Speed of backup.
 > 
 > In both cases only changed/new files use disk space according to the 
 > hardlink 
 > concept of BackupPC.
 > 
 > We have also detected, that in some cases incremental backups need much more 
 > time than full backups (factor 3-5) This sounds odd to us.
Seems odd...
 > 
 > Thanx
 > Thomas Birnthaler
 > -- 
 > OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
 > tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
 > Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
 > Thomas Birnthaler / +49 171-3047465 / t...@ostc.de / pgp 0xFEE7EB4C
 > Hermann Gottschalk / +49 173-3600680 / h...@ostc.de / pgp 0x0B2D8EEA
 > 
 > --
 > Check out the new SourceForge.net Marketplace.
 > It is the best place to buy or sell services for
 > just about anything Open Source.
 > http://p.sf.net/sfu/Xq1LFB
 > ___
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 > List:https://lists.sourceforge.net/lists/listinfo/backuppc-users
 > Wiki:http://backuppc.wiki.sourceforge.net
 > Project: http://backuppc.sourceforge.net/
 > 

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Holger Parplies]

Hi,

Thomas Birnthaler wrote on 2009-01-09 00:00:53 +0100 [[BackupPC-users] How to 
delete backups? + Benefit of incremental backups?]:
> [...]
> 1. We wonder why neither the GUI nor the commands offer a possibility to 
> delete backups (full and incremental). If e.g. the backup partition is filled 
> up, this would be very helpful.

it's usually not necessary (because BackupPC deletes backups when they expire)
or desired (until they expire, they should not be deleted). Furthermore, it's
a "dangerous" operation. I would argue against making that available with one
or two clicks on a web page.

> [...]
> 2. What is real benefit of incremental backups compared to full backups?

They are, in general (and if used correctly) significantly faster. They put
less strain on server and client disks. This has been answered many times.

Tino Schwarze wrote on 2009-01-09 01:17:21 +0100 [Re: [BackupPC-users] How to 
delete backups? + Benefit of incremental backups?]:
> > I argue they are just missing in the respective backup hardlink tree.
> > So if you delete the backup hardlink tree, the "holes" disappear?
> 
> There are a lot more cases to consider. I wouldn't risk getting an
> inconsistend view of the backups... see below.

The most important one, as a simple example:

First full backup contains only file 'a'.
Second full backup contains files 'a' and 'b'.
Incremental after second full contains only file 'c' (meaning the target
directory actually contained files 'a', 'b' and 'c').

Now remove the second full backup. Your incremental will now be interpreted as
containing files 'a' and 'c'. File 'b' has vanished. Note that this is a state
in which your original file system has been *at no point in time*. You not
only lose data, you get an inconsistent state.

Future rsync incrementals *should* fix that (or fail - not sure), because they
would be run against the contents of the reference backup. If BackupPC finds
the first full backup as a reference (again: not sure if that happens), then
all changes would be transferred. My guess is that if that does not happen,
the incremental would be done against an empty tree, thus transferring
*everything* (which is more than a full would do).
tar/smb incrementals are only based on a timestamp. Again, I'm not sure what
would be considered as the reference backup (since the real reference has
disappeared). If, somehow, the *time stamp* of the deleted backup were used,
the problem would *not* be fixed. File 'b' wasn't modified since the time
stamp - no reason to back it up.

In short: don't do it. What is the point of removing comparatively "young"
full backups (that have incrementals depending upon them) anyway? Wouldn't you
remove the *oldest* backups? Or *correctly* use the exponential strategy
BackupPC provides?

Someone in this thread wrote that BackupPC takes care of deleting dependant
incrementals with the expiring full. That is *not* correct. BackupPC actually
delays deleting the full backup until it is no longer needed, because there
are no dependant backups left. This is the sensible thing to do. Remove the
dependant incrementals rather than the full backup. Following your own
argumentation, removing an incremental will free just as much space as
removing a full would [well, that's not true, but you get the idea].

> > But this is just management space (directories and their dentries) ---
> > which uses of course some inode and data space. No additional data space
> > and inode space is needed for the real files in full backups compared to
> > a incremental backup. Is that correct?
> 
> Yes.

Almost. All *directories* are created for an incremental anyway (not only
directories containing changes). Without the entries for unchanged files, the
directories will be shorter, same number of inodes, though.
If the maximum hard link count is exceeded for a file, you will get a new
copy of it in the pool. While 32000 possible links is *a lot*, you still may
get overflows, and you'll get them sooner with only full backups. Just a
detail.

> What are you trying to achieve, after all? Please tell us about the
> problem you're trying to solve - there might be easier approaches.

This question is *important*. All of the points made here have been made *a
lot* of times. You are trying to do something that doesn't seem to make sense,
but, presumably, the problem you are trying to solve *does* exist. I would
rather help you solve a problem than criticize your questions.

> > > > We have also detected, that in some cases incremental backups need much
> > > > more time than full backups (factor 3-5) This sounds odd to us.
> > >
> > > What transfer method are you using?
> 

Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Tino Schwarze]

Hi Thomas,

> > Your web view would become inconsistent (e.g. deleted files becoming
> > visible again).
> Ok, this seems to be a case we forgot ;-(
> But if this doesn't matter to us, is it then okay to delete any backup?
> Do the GUI and the creation of new backups work and don't throw errors?
> 
> By the way: How are deleted files represented?

They are marked as deleted in the fattrib files.

> I argue they are just missing in the respective backup hardlink tree.
> So if you delete the backup hardlink tree, the "holes" disappear?

There are a lot more cases to consider. I wouldn't risk getting an
inconsistend view of the backups... see below.

> > > In both cases only changed/new files use disk space according to the
> > > hardlink concept of BackupPC.
> >
> > Yes. Fulls need some more space because they are completely filled, that
> > is, all directories contain hardlinks to all the files, whereas
> > incrementals only contain hardlinks to new and changed files -
> > filesystem-wise they've got holes which are filled by the CGI.
> But this is just management space (directories and their dentries) --- which 
> uses of course some inode and data space. No additional data space and inode 
> space is needed for the real files in full backups compared to a incremental 
> backup. Is that correct?

Yes.

> If this is the case we think about doing full backups all the time.
> So deletion of backups is ok then too.

I wouldn't do that. You could use the $Conf{IncrFill} option. Then each
incremental is filled up and does not depend on previous incrementals
(except for doing actual backup).

What are you trying to achieve, after all? Please tell us about the
problem you're trying to solve - there might be easier approaches.
BackupPC automatically deletes too old backups and takes care for
keeping/deleting depending incrementals as long as neccessary.

> > > We have also detected, that in some cases incremental backups need much
> > > more time than full backups (factor 3-5) This sounds odd to us.
> >
> > What transfer method are you using?
>
> rsync over GBit networks between Linux machines and also between MacOS 
> machines. In both cases that effect happens.

That's strange. Please have a look at the server's and client's load
during incremental backup - maybe something is running on either of them
which takes a lot of CPU and/or network and/or memory...

HTH,

Tino.

-- 
"What we nourish flourishes." - "Was wir nähren erblüht."

www.lichtkreis-chemnitz.de
www.craniosacralzentrum.de

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Ryan Manikowski]

http://backuppc.wiki.sourceforge.net/How+to+delete+backups

Ryan Manikowski

System Administrator
2ergo Americas Inc.
 
:703.677.8499:
www.2ergo.com
Arlington, VA

 
This message (including attachments) is confidential and may be legally 
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not disclose, copy or use any part of it.  Please delete all copies immediately 
and notify the sender. 2ergo Americas Inc. was formerly known as Proteus Inc.



Thomas Birnthaler wrote:
> Hello,
>
> we are using BackupPC and it works perfect on different places.
> But we have 2 questions on it:
>
> 1. We wonder why neither the GUI nor the commands offer a possibility to 
> delete backups (full and incremental). If e.g. the backup partition is filled 
> up, this would be very helpful.
>
> As far as we understood the concept of using hardlinks and different 
> directories for each backup + a hash pool for each file it seems to be very 
> easy to delete a backup NN.
>
> Just delete recursively the backup directory NN and the nightly run will 
> really destroy all orphaned files with a hardlink count of 1.
>
> If a full backup is deleted that way, incremental backups depending on it 
> then 
> depend on the next earlyer full backup and work as before. Same is true for 
> incremental backups. So the GUI works as before and the creation of new 
> backups too.
>
> Is that idea correct?
>
> 2. What is real benefit of incremental backups compared to full backups?
>
> In both cases only changed/new files use disk space according to the hardlink 
> concept of BackupPC.
>
> We have also detected, that in some cases incremental backups need much more 
> time than full backups (factor 3-5) This sounds odd to us.
>
> Thanx
> Thomas Birnthaler
>   

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Les Mikesell]

Thomas Birnthaler wrote:
>
> 2. What is real benefit of incremental backups compared to full backups?

Normally they are faster and with non-rsync methods transfer much less data.

> In both cases only changed/new files use disk space according to the hardlink 
> concept of BackupPC.

That's after they get to the server.

> We have also detected, that in some cases incremental backups need much more 
> time than full backups (factor 3-5) This sounds odd to us.

This sounds like you are using rsync and doing infrequent fulls. 
Normally rsync incrementals transfer everything that has changed since 
the last full which is the comparison base.  Files added after the full 
are copied over again in every subsequent incremental.  If you have 3.x 
you can change this with $Conf{IncrLevels}.

Hmmm, it still doesn't make sense that a full would be faster than the 
prior incremental, though.  Are you sure you are comparing apples to 
apples on this?  Rsync incrementals should quickly ignore any files 
where the timestamp and size matches the backuppc copy where fulls will 
do the rsync block checksum compare over everything.


-- 
   Les Mikesell
lesmikes...@gmail.com



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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Thomas Birnthaler]

Wow Tino,

your faster anwering than I'm able to question ;-)

> Your web view would become inconsistent (e.g. deleted files becoming
> visible again).
Ok, this seems to be a case we forgot ;-(
But if this doesn't matter to us, is it then okay to delete any backup?
Do the GUI and the creation of new backups work and don't throw errors?

By the way: How are deleted files represented?
I argue they are just missing in the respective backup hardlink tree.
So if you delete the backup hardlink tree, the "holes" disappear?

> > In both cases only changed/new files use disk space according to the
> > hardlink concept of BackupPC.
>
> Yes. Fulls need some more space because they are completely filled, that
> is, all directories contain hardlinks to all the files, whereas
> incrementals only contain hardlinks to new and changed files -
> filesystem-wise they've got holes which are filled by the CGI.
But this is just management space (directories and their dentries) --- which 
uses of course some inode and data space. No additional data space and inode 
space is needed for the real files in full backups compared to a incremental 
backup. Is that correct?

If this is the case we think about doing full backups all the time.
So deletion of backups is ok then too.

> > We have also detected, that in some cases incremental backups need much
> > more time than full backups (factor 3-5) This sounds odd to us.
>
> What transfer method are you using?
rsync over GBit networks between Linux machines and also between MacOS 
machines. In both cases that effect happens.

Thomas Birnthaler
-- 
OSTC Open Source Training and Consulting GmbH / HRB Nuernberg 20032
tel +49 911-3474544 / fax +49 911-1806277 / http://www.ostc.de
Delsenbachweg 32 / D-90425 Nuernberg / Geschaeftsfuehrung:
Thomas Birnthaler / +49 171-3047465 / t...@ostc.de / pgp 0xFEE7EB4C
Hermann Gottschalk / +49 173-3600680 / h...@ostc.de / pgp 0x0B2D8EEA

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Re: [BackupPC-users] How to delete backups? + Benefit of incremental backups?

[Tino Schwarze]

On Fri, Jan 09, 2009 at 12:00:53AM +0100, Thomas Birnthaler wrote:

> we are using BackupPC and it works perfect on different places.
> But we have 2 questions on it:
> 
> 1. We wonder why neither the GUI nor the commands offer a possibility to 
> delete backups (full and incremental). If e.g. the backup partition is filled 
> up, this would be very helpful.
> 
> As far as we understood the concept of using hardlinks and different 
> directories for each backup + a hash pool for each file it seems to be very 
> easy to delete a backup NN.
> 
> Just delete recursively the backup directory NN and the nightly run will 
> really destroy all orphaned files with a hardlink count of 1.
> 
> If a full backup is deleted that way, incremental backups depending on it 
> then 
> depend on the next earlyer full backup and work as before. Same is true for 
> incremental backups. So the GUI works as before and the creation of new 
> backups too.
> 
> Is that idea correct?

Almost. ;-) You should not delete a full backup if there are some
incrementals depending on it. Rule: Only delete a level-n incremental if
there is no level-n+1 incremental (with n=0 for fulls).

Your web view would become inconsistent (e.g. deleted files becoming
visible again).

> In both cases only changed/new files use disk space according to the hardlink 
> concept of BackupPC.
 
Yes. Fulls need some more space because they are completely filled, that
is, all directories contain hardlinks to all the files, whereas
incrementals only contain hardlinks to new and changed files -
filesystem-wise they've got holes which are filled by the CGI.

> We have also detected, that in some cases incremental backups need much more 
> time than full backups (factor 3-5) This sounds odd to us.

What transfer method are you using?

HTH,

Tino.

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