Subject Re: [firebird-support] Re: nbackup strategy advice
Author Kjell Rilbe
Den 2014-03-16 11:58 skrev Paul Vinkenoog såhär:
> Kjell Rilbe wrote:
> > First day of year: N=0, initial complete backup.
> > First day of each month: N=1, will contain all pages changed since first
> > day of year.
> > First day of each week: N=2, will contain all pages changed since first
> > day of month.
> > Each day: N=3, will contain all pages changed since first day of week.
> >
> > If two such days coincide, you still need to run both "colliding" levels
> > (lower N first, higher N directly afterwards), or the sequence will be
> > broken next day.
> That's not necessary, and the higher level backup will add nothing on
> that moment.
> Suppose you make a level-2 backup every Sunday. Then it makes sense to
> schedule the level-3 backups daily from Mon-Sat.
> If you want to make a point-in-time restore later, it will involve 4 files
> if that point in time is on Mon-Sat, and 3 files if it is on a Sunday.
> (And 2 files if it is the first day of the month.)
> All you have to do is determine the most recent backup before the chosen
> point in time. If that is a level N, you need N+1 files for the restore
> (levels 0-N, each one being the most recent file of that level before
> time 'T').

My idea was to avoid having to keep track of N for last backup. The
script & scheduling would be a bit simpler. And I do realize the N=1
backup right after the N=0 backup will store nothing. It will, however,
make it possible to do the N=2 backup next day and have a complete
N-chain. Skipping the N=1 backup and go right for N=2 won't work. or am
I missing something?