[lbackup-discussion] Time point backup schema?

[henri]

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


>> If you were to successfully run a backup each day and you have
>> specified 365 rotations (numRotations=365) in the configuration file,
>> then after 365 executions you will be able to restore the entire
>> backup directory or any sub directories or files from the backup for
>> any from any of the  356 snapshots in your backup. When LBackup is  
>> run
>> for the 356th time with this configuration, the oldest snapshot will
>> be removed, provided the backup 365th backup completes successfully.
>
> Yeah, I think this is reasonable. Cause each file have a life cycle.  
> If
> we set "numRotations=?" properly.
>>


>> 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.


> 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.

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/

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.

Again if you have any further questions please let me know.

Kind regards
Henri