OVM mount point changed to Read only

Dear Fellows,

We are using Oracle VM 3.3.3 and Oracle Linux is installed on that.  While copying 350 GB of database files (nearly 2-5 GB each) the mount point is changing to read only after completing 275 GB of copy. There is still enough space left at the mount point level, initially when the issue had cropped up we have 80 GB free space left. To resolve this we have removed some other dir's and restarted the VM and was working fine. Again when we started copying, the mount point had changed to Read only.

When noticed we found that the OVS repository for the mount point is 100% used but our concern here is how that repository filled when there is still half of the space left on the mount point and the repository is not presented to any other VM's except the guest hosting the VM.