Bill Bogstad wrote:
Recent? versions of VirtualBox have an option to control "host io caching". Their documentation states that VirtualBox uses its own "small cache" to buffer writes even if you turn off "host io caching". No idea what that means.
"Host I/O caching" is the host's I/O cache. On Unix it's the kernel I/O buffers used for async mounts. On Windows it's the write policies for disk devices.
VirtualBox can't actually turn off a host's I/O cache. All it can do is issue fsync or FlushFileBuffers calls against VM container files upon request from guests. There is still some host-level cache involved between when the guest finishes writing and issues the flush call and when the host can act upon VirtualBox's flush call.
VirtualBox may have its own supplemental write cache that cannot be disabled. I don't know for sure and I don't really care. I finally gave up on VirtualBox a couple of years ago after a Linux guest crashed the hypervisor which in turn crashed the Linux host.
-- Rich P. _______________________________________________ Discuss mailing list [email protected] http://lists.blu.org/mailman/listinfo/discuss
