Re: [exim] FreeBSD ffs vs. ufs?

Marcus Barczak <mbarczak@???> wrote:
> [exim] FreeBSD ffs vs. ufs?
> Date: 06-07-17 12:00 am
> From: Marcus Barczak <mbarczak@???>
> To: exim-users@???
>
[...]
> I was wondering if anyone had any positive or negative experience  
> with using ffs+soft updates with exim on a FreeBSD system?  I  
> understand the risk of losing data in the event of a power failure  
> (soft updates not being written to disk immediately).  I'm just  
> wondering if there are any other gotchas that aren't immediately  
> obvious.

There is a gotcha regarding power failure that you may not be aware of.
Softupdates mode is very resistant to corruption due to power failure,
except that some consumer grade hard drives lie and return a status that
says they have written data to the platter when it is still actually in the
drive's on-board cache, so Softupdates thinks the data is safely written
when it is not. With those drives the only way to make them resistant to
power failure is to turn off the on-board write cache entirely, which is
likely to significantly slow down writes. With drives that don't lie (as
far as I know, that includes all server grade drives) there isn't a
problem. More details available in various FreeBSD list archives.

- Bob