1.How to covert parallels vm to virtualbox
On "Terminal", using "cp" to copy .hds file to .hdd example:
sp4wnr0ot$ cp -i ˜/Documents/Parallels/win7.pvm/Windows7-0.hdd.0.{5fbaabe3-6958-40ff-92a7-860e329aab41}.hds ~/vms-converted/win7.hdd
#cp -i Windows\ 10-0.hdd.0.\{5fbaabe3-6958-40ff-92a7-860e329aab41\}.hds /Volumes/My\ Book\ Thunderbolt\ Duo/online_VM_os/win10.hdd
Second and last step:
2.Open VirtualBox, New Virtual Machine and then "Import Disk From an Existing File", Navigate to previous file copied "win7.hdd", that's it.
2.export ovf through virutalbox
3.use ovftool to upload ova files
4.covert ova to ovf for editing ovf file to reslove the virual hardware is not supported issue