I am performing a migration of Windows 10 VM running on HyperV to OpenStack setup with Ussuri(qemu KVM) on Debian 10 nodes. 

I got the Windows VM exported disks as    disk1.VHDX and disk2.avhdx files from my WIndows cloud Vendor.

1. As my understanding  I need to convert these VM disks from HyperV using virt-v2v  tool.  ( Could someone explain what is the relevance of this step and is it mandatory for importing it to  my Ussuri Openstack cloud which uses qemu-kvm hypervisor.

2.  As I've read   I tried to convert this   disk1.VHDX file with the follwoing step

#virt-v2v -i disk disk1.VHDX -o local -os /home/cloud

this step fails with virt-v2v error :

// Files system was mounted read only . even though we sked for it to be mounted read-write. This usually means that file system was not cleanly unmounted. Possible causes include trying to convert a guest which is running. or use Windows hibernation or Fast Restart . 

Original error message touch: open /8imepyi7: Read only file system ...

Can anyone guide what causes this error and Is there a fix or work around available to solve this error in vrit-v2v conversion ?

Thanks in advance

krish