OpenNebula

Here's the patch :

Edit src/vmm/LibVirtDriverKVM.cc, add around line 56

string  cache                = "";
string  default_driver_cache = "";

Edit src/vmm/LibVirtDriverKVM.cc, add around line 274

get_default("DISK","CACHE",default_driver_cache);

if (default_driver_cache.empty())
{
   default_driver_cache = "default";
}

Edit src/vmm/LibVirtDriverKVM.cc, add around line 295

cache = disk->vector_value("CACHE");

Edit the same file, starting from line 372 (considering the new line added above). The file should look like

        // ---- Image Format using qemu driver ----

        file << "\t\t\t<driver name='qemu' type='";

        if ( !driver.empty() )
        {
            file << driver << "'";
        }
        else
        {
            file << default_driver << "'";
        }

        file << " cache='";
        if ( !cache.empty() )
        {
            file << cache << "'/>" << endl;
        }
        else
        {
            file << default_driver_cache << "'/>" << endl;
        }

        file << "\t\t</disk>" << endl;

Finaly edit one/etc/vmm_ssh/vmm_ssh_kvm.conf and add something like :

DISK     = [ driver = "raw", cache = "writeback" ]