Thank you very much, I see manual copy as best option now as using autovmbackup script and some other scripts often fail even with VM powered off.
Backing up 4x 100GB VMs with speed 50-75MB is really test of someones nerves, lol. Used 10GB NICs in VMware and Synology/Qnap as targets before and it was like 300-500 MB/s to old spinning HDDs in RAID5.
I even used Unassigned HDD as a target, used turbo write, shut down parity and cant get more than 75MB/s when backing up VMs from cache SSD in RAID0 to array or unassigned brtfs HDD.
Recalculating parity or precleaning HDDs is 180 MB/s - real/advertised speed of single HDD.
I understand parity thing - just its really slow for my use. Maybe all SSD array /TRIM thing resolved/ could be my solution in the future...
One more idea: use brtfs SSD pool in Unassigned devices as backup target ? but thats insane price ratio wise.