Re: Plan: journalling fixes for WAPBL

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Sep 23, 2016 at 01:46:09PM -0400, Thor Lancelot Simon wrote:
> > > This seems like the key thing needed to avoid FUA: to implement fsync() you just wait for notifications of completion to be received, and once you have those for all requests pending when fsync was called, or started as part of the fsync, then you're done.
> > 
> > *if you have the write cache disabled*
> 
> *Running with the write cache enabled is a bad idea*

On ATA devices, you can't permanently disable the write cache. You have
to do it on every power cycles.

Well this really needs to be carefully evaluated. With only 32 tags I'm not
sure you can efficiently use recent devices with the write cache
disabled (most enterprise disks have a 64M cache these days)

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--