Comment 3 for bug 1733286

From irc manila community meeting 15 February:

<bswartz> This is generic driver specific
<bswartz> I think there are caching/timing issues with how it does snapshots
<bswartz> We just take a cinder snapshot and assume that the right thing happens
<bswartz> If there's unwritten data in the service VM's cache though, it can get missed by the snapshot
<dustins> bswartz: I guess it depends on how driven we are to fix this thing with the Generic driver
<bswartz> The correct behavior would probably be to flush the write caches of the service VM before taking the cinder snasphot