My linux (ubuntu) VM sometime get OS disk corrupt, remount to read-only and have to run fsck to check the disk. Sometimes fsck work, but sometimes, when it tried to fix the disk, it deleted the file which can be system file or database file.
This happen for the VM disk on NFS.
Thanks for all your troubles
Host OS: Ubuntu 18.04
Software: Opennebula 5.6 with KVM
Other: FreeNas 11.1