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Number   :  3696
Date     :  2003-02-12
Author   :  Jonathan B.
Subject  :  Re: "True" Incremental Backups
Size(KB) :  1


>The biggest flaw with this, conceptually, is that if you decide to
>revert to a point (say) 10 days after your first ("full") backup, and
>you do so by copying the contents of your full backup back, followed
>by your day-1 incremental, your day-2 incremental, etc -- you will
>end up with every file that you ever had at end-of-day. That is,
>none of the file deletions that you had done would be in effect...

Your point is well taken. If we were to continue this conversation with 
regard to XXCOPY, then a solution would be to maintain some sort of metadata 
in the destination folder that was a sort of XXCOPY differential report. 
This metadata file might contain the list of deleted files (and optionally 
changed or added files). For example, the file contents might look like 
this:

--[XXCOPY.metadata]--------------
-c:\sourcePath\deletedFile1.dat
+c:\sourcePath\newFile1.dat
~c:\sourcePath\changedFile1.dat
---------------------------------

If we limited the metadata to simply deletions (in the default case), then 
this file would generally be VERY small, if present at all. Of course if 
this file already existed in the source, it would have to be renamed in the 
output (such as XXCOPY.metadata.bak) or simply replaced as a reserved XXCOPY 
filename.

In the case of a restore, one would successively restore first from the full 
and then from the incremental backups, one at a time. After each restore 
operation, either XXCOPY or a script could process this metadata file and 
remove the files that are listed as having been deleted at that point in 
time.

Anyone else have a comment or opinion on this?

-Jonathan

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