Hello, atunccekic!

Friday, December 20, 2013, 12:35:54 PM, you wrote:

adct> It's no big deal but,
adct> Maybe it can be written in the help like :
adct> Use or not direct I/O when scanning database (Default: Off)

I think there is a mistake, because nbackup is a part of Firebird
server, so it can't change Forced Write mode for the database where
clients are working.
So, -d option can be used only for the target file, not "when scanning
database"
But, yes, it is inetersing to know the default of -d option, anyway.

adct> And why am I searching on this.. My system crawled while doing
adct> a -B 0 level nbackup today, which I have never tried before.
adct> Everything was fine when it finished.

you are lucky. nbackup can "lock" if some of fb_inet_server processes
has not finished writing changed pages.
You will see that your delta grows constantly.

adct> But the db file is 28gb having many connections and it took
adct> about 10minutes to complete.

10 minutes for 28gb I think is ok. You have good hardware (disks), and I'm
sure that you made nbackup to another physical disk, or at least to
another logical disk on your RAID 10.

adct> And now I'm hasitating to start the -B 1 level nbackup.
adct> Will it suspend every connection?

no. why?

adct> Will it take long?

In FB 2.x nbackup always scan the whole DB, for any nbackup level.
So, it will take only a bit less time for -b 1, -b 2, etc.
This behavior will be fixed in Firebird 3.0 (only changed pages
will be scanned).

adct> Should I update to 2.5.2 first?

yes, sure, by lot of other reasons. But not all things related to nbackup are fixed.

--
Dmitry Kuzmenko, www.ib-aid.com