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'). Cheers, Paul Vinkenoog
