QEMU DVD-ROM out of storage

[bluuurb]

I'm running an Ubuntu VM with a download client in it. All was well until I got the message from the download client (BiglyBT) that my storage was full. This is odd as all file folders point to an NFS mount on the main array. After looking around I saw that the QEMU DVD-ROM had 0 bytes available, while I remember that this was not the case at first boot.

It could very well be that BiglyBT is the cause of the issue. However, I was wondering if anyone could point me in the right direction. I've tried to increase the RAM and the VDISK size, both had no impact on the QEMU DVD-ROM.  Since the DVD-ROM is full, BiglyBT crashes after a night of running so it is a bit annoying. 

What I tried:

 - Increase VDISK size

 - Increase allocated RAM
 - Reinstall entire VM

The maintainer of BiglyBT just said: "If I was to make a random guess I'd say you were running out of Java VM heap memory and need to increase it." So far I did not find instructions on how to do this.

I know its all a bit vague so if more information is required, I'd be happy to supply it. Any help is welcome. I've attached screens of the storage usage.
 

PS: I'm aware I have a chunk of storage unallocated on the VirtIO disk.