[stefanha]

This benchmark is bogus because the iozone -I flag is missing. -I uses O_DIRECT to avoid the page cache.

Due to page cache usage it's hard to say what this benchmark is comparing. The I/O pattern seen by the actual disk, shared folder, or NFS may be different between benchmark runs. It all depends on amount of RAM available, state of cache, readahead, write-behind, etc.

Please rerun the benchmark with -I to get an apples-to-apples comparison.

[kika]

It will avoid page cache in the VM, but will not avoid cache on the host, right?

[vl]

Depends on configuration, but most setups propagate O_DIRECT all the way through - otherwise it would be impossible to run many apps, such as DBs in VM.