My Mac locked up! While this may not be surprising, it’s worth noting as my Mac virtually never hangs. Had the look and feel of a filesystem hang. The userinterface updated nicely, all network ports accepted connections, but the windowsmanager wouldn’t respond to any clicks, just moving the mouse and the ports never presented anything much, and it all happened upon multiple known writes. Anyways, only lost data is a save of a mail that had been sent before the hang.