On Fri, Dec 23, 2022, at 12:56 AM, Demi Marie Obenour wrote:
Why cache mode unsafe? How big a performance win is it?
Huge. In effect fsync is ignored. So if the host dies, write order is not guaranteed and
can toast the guest file system.
The guest dying shouldn't pose a problem because the write order is eventually honored
by the host. There's a variety of complex journal replay behaviors of the various file
systems that'll come into play (no pun intended).
--
Chris Murphy