--- In firebird-support@yahoogroups.com, Anderson Farias wrote:

>
> Hi,
>
> I did a level 0 (full) backup of a 8GB with nbackup. It created a 8Gb file and took about 8 minutes. Good!
>
> Right after that, for testing porpouses, I did a level 1 backup on the same database, an nbackup created a 100 Kb file and took about 5 minutes!!
>
> My question is:
>
> 1) why the level 1 backup takes so much time (almost as much as level 0)? (I thought it was meant to work very fast)

Because nbackup of any level should read whole database to find pages changed since last backup.
It is improved in FB3.

> 2) why does level 1 creates this 100 Kb backup file if nothing has changed in the database between level 0 and level 1 backup?

Header page was changed, probably there was more changes you doesn't know of (background garbage collection, for example)

Regards,
Vlad