Den 2014-03-16 07:27 skrev hugo.lar...@yahoo.com såhär: > > Hello Paul. > Thanks for your advice. > My strategy was based on "backup data once" approach but this would > produce to many files I now realize. > > But I still want to avoid to backup the entire database (N=0) on > regular basis. > Whats your opinion about this approach? > First backup N=0 > Every day N=1 for a month (replace file each time) > Increment N next month. > > This would produce 12 files every year. >
That wouldn't work. I don't think you understand how Nbackup works. N=0 backs up everything. N=1 backs up every page that's changed since last N=0. N=2 backs up every page that's changed since last N=1. ... N=k backs up every page that's changed since last N=k-1. So, with your suggested scheme, first month would go like this: Day 1: backup entire database (N=0). Day 2: backup pages changed since day 1 (N=1). Day 3: backup pages changed since day 1 (N=1). Will include all pages copied day 2 + additional pages changed since day 2. Day 4: backup pages changed since day 1 (N=1). Will include all pages copied day 3 + additional pages changed since day 3. ... Day 28/30/31: backup pages changed since day 1 (N=1). Will include all pages copied the day before + additional pages changed the last day. If Month 2 you increment N to 2, you will get this: Day 1: backup pages changed since last day of month 1 (N=2). Day 2: backup pages changed since last day of month 1 (N=2). ... Day 28/30/31: backup pages changed since last day of month 1 (N=2). At the end of the year, your actual "final" backup sequence will be: N=0: Initial backup first day of the year. N=1: Last backup of month 1. N=2: Last backup of month 2. ... N=12: Last backup of month 12. It would probably make more sense to do it like this: 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. This way, you will have a daily backup that's complete, consisting of four parts (N=0, 1, 2 and 3). In general, Nbackup should be run with each value of N at a regular interval, with tighter intervals for higher values of N. Incrementing N over time as you suggested is not suitable. Note that Nbackup has no way of detecting any database corruptions, so if that happens it will go completely undetected. Might be a good idea to combine it with some client local gbak or gfix- v or gfix -v -full, as often as is viable. I might also mention the possibility to simply lock the database with Nbackup and copy the database file with rsync. This will probably have similar or better performance over a slow connection. That's what I do for out 200 Gbyte database, although that's on a single server with a backup volume attached via high bandwidth network. :-) Regards, Kjell