If a disk is dying and in read only mode, many applications will fail, such as b2 for backups, because they want to write to /tmp

To just temporarily move /tmp to a RAM File System, you can use the following command

mount -o mode=1777,nosuid,nodev -t tmpfs tmpfs /tmp

¹⁾

This will make all current files in /tmp inaccessible other than open inodes. But for a disaster recovery thats fine