failed with the following error: "Write on "....bak" failed: 27(error not found) BACKUP DATABASE is terminating abnormally
Standard options for me to check would be the following, but this has been done by you or does not match exactly because the backup at least starts:


Disk space sufficient? (If possible do a chkdsk)
Write Access granted to SQL Server? 


Next step would be to check throughput of backup drive because SQL Server backup is sensible in this area, some timers in the background are watching. Backup to a USB-Drive / Stick is usually a very bad idea because of this.

Now for the more exotic stuff:


H:-Drive is NTFS formatted? Otherwise File size >4 GB might be an issue.
As we are dealing with a VM here: Is there some kind of disc overcommitment happening on Hyper-V or SAN level? Just because you see a e.g. 1 TB drive does not guarantee that this is covered by physical disks somewhere.
Any I/O errors in windows system event log? If something really bad is happing on I/O level you can find it there.