I can't see the default option for Direct I/O in my system. On or Off?  It's an ubuntu 64bit with firebird 2.5.0 classic.

There's a story about it in the nbackup-backups file but I can't clearly figure out and be sure what the default is.

It's no big deal but, 

Maybe it can be written in the help like :   

Use or not direct I/O when scanning database (Default: Off) 

Maybe it can be written on the console as a single line when nbackup is started? 

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

But the db file is 28gb having many connections and it took about 10minutes to complete. And now I'm hasitating to start the -B 1 level nbackup.

Will it suspend every connection?

Will it take long? 

Should I update to 2.5.2 first?

Thank you