ZFS IO issues/limitations inside VMs

[guletz]

Is it generally wrong to have all VMs use .raw disk inside a directory on a ZFS pool?

No! As a example I see on a friend of mine some time ago a win install on a almost 1 TB raw file on zfs!

 

[guletz]

If i understood correctly without SLOG im writing double to my SSDmirror, so ~200mb/s should be good?

Not so exact! SLOG is useful only the application need to write in syncron(Direct I/O) mode(tipycal DataBases). Any other app(mostly) except DB use async IO. A clasic file copy like in your test will use async.