Before all, make sure enabled ssh and shell on esxi host already.
1. Download rsync for esxi binary file from:
https://damiendebin.net/blog/2013/12/06/esxi-5-dot-1-and-rsync/
2. ssh to esxi host and upload(use sftp) rsync-static.
3. Enable ssh port on esxi host firewall
Login vsphere client->Configuration->Security Profile->Properies->Secure Shell->ssh client, and check it on
4. Use rsync-static transfer vmdk files.
./rsync-static --partial --progress --rsh=ssh -r 'root@x.x.x.x:/vmfs/volumes/datastore1/' .
Reference link:
https://www.digitalocean.com/community/tutorials/how-to-use-rsync-to-sync-local-and-remote-directories-on-a-vps