[lbackup-discussion] Time point backup schema?

[Daniel.Li]

Resend.

On Wed, 2009-03-11 at 15:28 +1300, henri wrote: 
> Dear Daniel,
> 
> Some great questions. Thank you.
> 
> >> Each time LBackup runs a snapshot of the backup directory is created.
> >> Once the backup has finished, I would encourage you to check the
> >> backup directory and make sure any important files have been
> >> successfully copied.
> >>
> >> The next time you run LBackup. A new snapshot tree will be created.
> >> Keep in mind that the old backup  snapshots still exist until they  
> >> are
> >> eventually deleted as specified within the configuration file.
> >
> > Humm,, it seems that LBackup will copy folders and set up an image  
> > file
> > (may be zipped) when running a snapshot.
> >
> > So I think it will sacrifice disk space for multiple snapshots, right?
> 
> On a *NIX system (ie Mac OS X) additional disk space will be required  
> for the new or altered files.
> 
> Most unaltered/unmodified files (resource forks and directories may  
> beehive differently) will consume no additional storage space on the  
> backup destination. However, because these files are hard links they  
> will consume inodes on the backup destination filesystem. The way all  
> of this works will eventually come down to the implementation of the  
> 'ln' command your file system and even operating system.
> 
> In essence, LBackup will only require additional storage for new or  
> changed files. Files which have not been modified between snapshots  
> are hard linked (not re-copied) and therefore will not require  
> additional storage. Creating a hard link means that virtually no  
> additional storage on the backup file system will be required.
> 
> The following URL will do a far better job of explaining the finer  
> points related to hard links : http://en.wikipedia.org/wiki/Hard_link
> 
Excellent! :)

So here is another related question about how it works to do the
snapshot to those altered files.

e.g. If I have a single file with the size of 10MB(for backup test
only).
I have slightly change one byte or one bit data at end of the file. How
much disk space will LBackup take for the next snapshot?

As u know, rsync just backup file to latest version, which will consumes
one byte/bit of the diskspace. Of cause, it does NOT have a snapshot
feature.

Now, we just lower the network requirement with rsync, which is ideal
for mirroring. So back to LBackup, how much space will LBackup takes
with the next snapshot, which is a key point to disk management.

.... cut ...... 
> 
> >> I recommend that you have a look at the "Basic Backup Local Machine"
> >> screen-cast for clarification on these points and if you have any
> >> further questions and contact me if you have any further questions.
> >> LBackup screen-casts are available from the following URL : http://lucidsystems.org/tools/lbackup/screencasts
> >
> >
> > I have just browse the source code. There are quite a few scripts,  
> > which
> > might be running under linux,right?
> 
> Yes LBackup is designed to run on *NIX and is supported on *NIX. There  
> is no reason why it would not be able to be ported to work on Windows  
> under cygwin.
> 
> However, at this point in time LBackup is completely untested and  
> unsupported on Windows.
> 
Thanks.

> 
> > I found that there are only Mac OS installer avaliable for users. I
> > checked
> > http://connect.homeunix.com/lbackup/operating_system_specific_builds.
> >
> > Is there any version available for Windows XP?
> 
> At this stage there is no installer for Windows XP. There is only  
> source code (scripts) available. These may work unaltered under Cygwin  
> or modifications may be required. As mentioned, LBackup is untested on  
> Windows systems.
> 
> There are currently no plans to create a Windows XP installer for  
> LBackup.  However, you are welcome to put somthing together if you are  
> able to get LBackup to running on successfully on Windows.
> 
> If you would like to make LBackup work on Windows, I will certainly  
> try to assist you. However, please keep in mind that running LBackup  
> on Windows is currently unsupported and untested and if it becomes to  
> difficult then you will be on your own.
> 
> If you are planning to run LBackup on a *NIX system and then back up a  
> Windows machine via the network then hard-linking should work fine  
> without major alterations to the code. There is a very good chance  
> that such a setup would work with out changes.
> 
Yes, I plan to use Windows XP just as a client :)

> 
> Regardless of whether you are still planning to use LBackup, you  
> should be aware of a project called Cygwin; which will allow you to  
> run rsync (the back-end for LBackup) on Windows. I am unsure of how  
> well rsync runs under Cygwin. At any rate I strongly suggest that you  
> have a look at the Cygwin project home page : http://www.cygwin.com/
> 
I think someone else has done the job ^_^
http://sourceforge.net/project/showfiles.php?group_id=69227&package_id=68081 

> The biggest issue in my mind with getting LBackup to work on windows  
> would be the support for hard links. However, according to Wikipedia  
> hard-linking is supported on Windows. However, I am unsure as to how  
> it is implemented.
> 
> > Hard links are supported by POSIX-compliant systems (such as Linux  
> > and Apple's OS X[1]), as well as Windows 2000 and later Windows NT  
> > operating systems.
> 
> 
> In conclusion my recommendation is that you look at the alternatives  
> to LBackup which are fully supported on Windows. The following URL  
> lists just a couple of options available : http://connect.homeunix.com/lbackup/about#alternatives_to_lbackup
> 
> > If you would like to run RSync on Microsoft Windows, you could  
> > consider installing RSync under Cygwin or you could take a look at  
> > DeltaCopy, nnBackup or NasBackup.
> 
> If you are still determined to get LBackup working on Windows, then I  
> am willing to try to assist you. However, I will re-iterate that  
> running LBackup on Windows is currently unsupported and untested.
> 
It's really very kind of you. Thanks very much for sharing those information.

Well, I think I need to take a look of each software to see which one is easy for us to integrate. :)

> Again if you have any further questions please let me know.
> 
> Kind regards
> Henri
> 
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-- 
Daniel.Li <lida_mail at 163.com>
PALFocus (http://palfocus.oicp.net)