[pve-devel] Default cache mode for VM hard drives

[Dietmar Maurer]

> You already reported a reproducible test case?
> 
> No, but he didn't want this.
> He said:
> *****************************************************************
> **
> Misbehaving upper layer results in potentially divergent blocks on the DRBD
> peers. Or would result in potentially divergent blocks on a local software RAID 1.
> ...
> Anyways.
> Point being: Either have those upper layers stop modifying buffers
> while they are in-flight (keyword: "stable pages").
> Kernel upgrade within the VMs may do it. Changing something in the
> "virtual IO path configuration" may do it. Or not.
> 
> Or live with the results, which are
> potentially not identical blocks on the DRBD peers.

Sorry, I do not get that. IMHO neither ubuntu, nor KVM is misbehaving (as it works
with all other storage types).