Re: FreeBSD UFS & fsync

On Mon, Feb 22, 2021 at 10:38 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> Do you have WCE enabled? In that case, modern Linux file systems
> would do a synchronous SYNCHRONIZE CACHE for our WAL fdatasync(), but
> FreeBSD UFS wouldn't as far as I know. It does know how to do that
> (there's a BIO_FLUSH operation, also used by ZFS), but as far as I can
> see UFS uses it just for its own file system meta-data crash safety
> currently (see softdep_synchronize()). (There is also no FUA flag for
> O_[D]SYNC writes, an even more modern invention.)

Apparently no WCE, but I could be looking at the wrong piece:

% sysctl kern.cam.ada | grep write_cache
kern.cam.ada.2.write_cache: -1
kern.cam.ada.1.write_cache: -1
kern.cam.ada.0.write_cache: -1
kern.cam.ada.write_cache: -1

I'm using sata disks, not scsi. Assuming I'm not looking at the wrong
parameter, I wil attach a scsi disk to do the same test and see if
something changes.
Or if you have any other suggestion about what to inspect, please advice.

Thanks,
Luca