On Fri, Nov 30, 2007 at 06:44:05PM -0800, fedora wrote:
> 
> >yup. I would say you are a bit confused.
> 
> >The 26th is the last full backup (the 0 in the column after the date), 
> >and the 29th is the most recent incremental based on that full (the 1 in 
> >the column after the date). Anything else is older, out of date, 
> >redundant . . . whatever you want to call it. If you had messed up a 
> >file and then it got backed up, you might want to go to an older one.
> 
> >What, exactly, is it that you are trying to do? And Why?
> 
> Actually I backed up one month (30 tapes). At the end of month tapes will be
> overwritten. So, I want to restore for the whole month before tapes being
> rotated for the new month because I want to make it as a archive for 1 year.
> (let say restore for November before December start). Correct me if I wrong
> for this understandings.

Consider that you may have some logfile, "/a/b/log",  that changes every day.
I.e. it logs new information every day.  For November you now have on tape 30
different copies of /a/b/log.  How can you "restore the whole month" of
/a/b/log, i.e. all 30 different versions, into a single location?

I hope it is obvious that you can't.  But you can say "I want the version
of /a/b/log that existed on November 1".  Or the version that existed on
November 30 or whatever other date you prefer.  Now extend that to all
the files on your system.  You can't restore to one directory tree each
backed up copy of each file.  But again, you can say give me a copy of
each file that existed on November 30.

So to save a "monthly" archive, you must pick a date within the month,
probably the first or last day of the month.  If on that date a level 0
backup was done, that is the only tape you need to restore.  If it was
a level 1 on that date you need the earlier level 0 and the level 1.
For levels 2 and 3 you need to restore 3 and 4 tapes respectively.
But not 30 days worth of tapes.  When you tell amrecover the date you
want, it figures out what tapes you need to use.

Note, an alternative to restoring and doing another backup for
archival purposes is to simply take the appropriate November tapes
and store them.  Then add new tapes to take their place.


-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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