[pve-devel] qemu-server: add directsync cache mode

[Dietmar Maurer]

> It's do a fsync on each write to be sure to not loose a single transaction.
> could be usefull for database by exemple, where we don't have to use host
> cache.

So maybe we should add a hint to the GUI that this is extremely slow?

> Also,some older linux (or "old" filesystem, could corrupt with cache="none" or
> cache"writeback", as they dont send flush command.
> 
> 
> some infos:
> http://lists.fedoraproject.org/pipermail/virt/2011-October/002956.html
> 
> 
> >> But why do we want to have a workaround for that?
> I just want to add all cache mode available in qemu. Maybe some users want it .

OK

> If I have time, I think i'll write a wiki article about cache options, as it's not
> simple to understand how they works.

That would be great.

- Dietmar