On Tue, Feb 28, 2017, at 02:08 PM, Josh England wrote: > It has always been an > annoyance to have to find the little bits and pieces in the OS (think > of a full RHEL/CentOS distro) that require the ability to write > somewhere As part of driving the [OSTree](https://ostree.readthedocs.io/en/latest/) model into Fedora/CentOS (well really rpm-ostree, which is part of Atomic Host), we have a read-only bind mount over /usr, and the only two writable directories are /etc and /var. In a diskless mode, then you could have /usr as a read-only NFS/cachefiles mount, and use tmpfs for /etc and /var. Ideally /etc can be read-only too during operation but that is definitely one where we hit things like LVM userspace writing there in the background: https://bugzilla.redhat.com/show_bug.cgi?id=1366584 But if something required writing to /usr at runtime in Fedora/CentOS that should be considered a bug.
