Alert when there is no writable space, but there is read-only free space available

[npelov]

It's possible to forget volumes as read only. I forgot few times a volume as readonly. I had set it readonly in order to fill other volumes which were fragmented (another issue hostd has - fills new space instead of filling freed space from closed contracts). But there can be other reasons that volumes are set as readonly - disaster recovery (raid) etc.
It would be nice to have an alert that says "There is not enough free space on writable volumes".
I can see how that can go wrong - if you set volume as read only to free it without huge IO from coping the data. then you might not want these alerts. So maybe it can be an option in settings:
[ ] alert me if all of my free space is read-only