Re: code 11: files changed during backup

Lasse Kliemann wrote:
> * Denis Corbin writes:
>  
> 
>>I agree, this is acceptable that dar appends several copies of a
>>'unclean' files up to the time it can:
>>- either properly save the file (which is no more recorded as 'unclean')
>>- reach the maximum retry count specified by the user.
>>
>>This feature should not be activated by default (a command line option
>>is required for that), file are still marked as 'unclean' but no retry
>>is performed by default.
>>
>>At restoration, unclean files are restored with a warning (for backward
>>compatibility this is better than not restoring them at all).
>>If a file has been saved several times (may the last copy be also an
>>unclean or a clean version of this file) only the last occurence is
>>"visible" and accessible to the user. The other copies (thus except the
>>last one) of a given file (clean or not) are just garbage in the archive.
>>
>>For testing or diffing, only the last copy of an unclean file is
>>considered (the diffing will most probably fail on such unclean files as
>>they were changing at the time of the backup).
>>
>>With theses restrictions, it seems possible to have this feature in dar.
> 
>  
> I agree with all of this.
> 

[...]

>>
>>Of course, it would not be much more complicated to have user definable
>>"and" and "or" operation between different type of criterium, like what
>>is done for EA or file selection. So far here I see several atomic tests:
>>- max number of retry per file
>>- max amount of already wasted bytes by unclean files in the archive
>>- max amount of byte to waste by unclean data for each file
>>
>>Theses could be "ANDed" or "ORed" to make something more complex like:
>>"(retry file at most n times) and ((do not waste more than 20MB for
>>unclean files) or (do not waste more than 500KB per file))"
>>
>>thus an unclean file of 1GB could be tried at most n times if there is
>>not yet more than 20MB of unclean data in the archive so far.
> 
> 
> Would this not mean, it is tried at most once, because after one failure 
> there is already more than 20MB wasted on unclean data? (This would not 
> contradict what you wrote, I just want to make sure I understand correct.)

Well, this was just a example on what could be possible to have with
several conditions ANDed together (this will be user choice to define
which criteria to use and how to build a logical expression with them.

That's true that if an unclean file has a size larger than 20MB we will
get more than 20MB of unclean data even if no retry is done... there is
no way to avoid this. However, if the size is less than 20MB a new retry
can take place.  The definition/name of this threshold (amount of byte
per archive) is probably no the best one, you are right.

> 
> 
>>... While
>>smaller files than 500KB could be tried at least n times even if already
>>more than 20MB of unclean data is present in the archive so far.
> 
> 
> Yes. Having these "AND"-"OR"-Feature would be near to an ultimate solution. I 
> am unsure whether this is really necessary, however. If I were you, it would 
> very much depend on the effort necessary to implement this.

Implementing this logical operator is not that much more complicated
than a set of switch that (three switches so far) which would be much
more restrictive.

> I presume that 
> the simple solution (three upper bounds) will be sufficient most of the time. 
> Maybe others on this list might want to express their views on this.
> 

The problem is that, it would be OK for you, but sooner or later some
will ask for some other  combination  of theses three switches or for
other switches... As the enhancement of an already implemented feature
may become complicated if its design is too restrictive, it is better to
directly go to something that can easily receive new logical operator as
well as new criteria... as much as the cost to implement is not extravagant.

> 
> Regards, Lasse
> 

Regards,
Denis.

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