Re: cache write back & barriers

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Hi,

> > In virt-manager I saw that there's the option for cache writeback for
> > storage devices.
> > I'm wondering: does this also make kvm to ignore write barriers invoked
> > by the virtual machine?
> 
> No, that would be unsafe.  When the guest issues a flush then QEMU will
> ensure that data reaches the disk with -drive cache=writeback.

Aha so the writeback behaves like the consume harddisks with write-cache
on them.
In that case maybe an extra note could be added to the virt-manager
(excellent software by the way!) that if the client vm supports
barriers, that write-back in that case then is safe. Agree?


Folkert van Heusden

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