cost of tdb transactions on ext4 with barriers

[tridge at samba.org]

Hi Ronnie,

 > Do you really need barriers on ext4?

It depends if you want your data to survive a machine crash. 

For my development box, I'm happy to risk losing a small amount of
data on a machine crash. For a production box it's not such a good
thing.

I'm not aware of anything unique in ext4 that allows it to avoid data
corruption on system crash with barriers off. Maybe Rusty knows of
something?

Cheers, Tridge