http://man.dragonflybsd.org/?command=HAMMER&section=5

HAMMER2 is I assume the same – look at the design document around line 129:

https://gitweb.dragonflybsd.org/dragonfly.git/blob/57614c517203403e7fe4a34c370c7151ba52c539:/sys/vfs/hammer2/DESIGN

I recall Matt was testing HAMMER when first designing it by loading up a machine with a very heavy disk load, then yanking the power cable out of the back. And then repeating it, over and over. So yeah, designed to handle power loss as well as possible.

How does hammer and/or hammer2 on single HDD behave at power outages (in an workstation scenario)? Linux with EXT4 or XFS have no problems.

Recently, I used FreeBSD 12 stable with ZFS (again, on a single HDD) as my main graphical workstation, happy with the performance, but after a series of power outages (frequently in my zone), some errors showed up at boot time and, even if the system was still working, my confidence disappeared. I am back on Linux Fedora + XFS now, but I always looked at DragonFlyBSD as more than a file server.

Thank you!