On 2021/02/25 13:28, Neal Gompa wrote
I'm not going to rehash all the arguments from the past decade,
The questions asked in 2012 weren't answered then, either. Many of the reasons stemmed from a need and presumption for /initrd, which I would think most would know isn't necessary either. Reasons for UsrMerge included a 33x inflated space needed for /root without it (email continued below this quoted message): -------- Original Message -------- Subject: Why is initrd needed... Date: Thu, 15 Nov 2012 00:17:47 -0800 From: Linda Walsh <suse(at)tlinx.org> To: opensuse-factory@opensuse.org, SuSE Linux <opensuse@opensuse.org> So far no one is able to explain why it is needed other than It's a fad or it's cool.. You have a 20MB RAM disc that you think you have to load and do secret things before you start my OS. I have a 12GB root disk (and RH/Fedora on their "Excuses for UsrMerge page, claims to need 400GB in root?! Talk about a broken model to be following!) Never the less, a 14 GB root with over 50% free.. and What, can't I put on my root hard disk that you have to have initrd? The drivers on my kernel are built-in. You are deliberately making people use a ram disk for no reason. Give me ANY reason. and don't say it's to mount /usr A "toy /usr/ that is not the full /usr partition lives on your ram disk in less than 20MB, I can throw away that much space in a 'dummy /usr' that the real /usr mounts over. It would be preferable to having to read all of it from disk and duplicating it 12 times for the 12 kernels I had in lilo when I last cleaned it out of initrd's that don't get used. Not only are you duplicating the space of all the utils in /usr that you need to put (ONLY because you moved them from /bin.. which if you hadn't done you wouldn't need to to copy them all to /usr). I read the /usrmerge propaganda... They miss a major point: If they want to merge /usr/bin with /bin, why not get rid of /usr/bin? Why not copy all of /usr/bin into /bin? But to boot do you really need 15G of /usr/share? Is /usr/games really required for boot? Do you need the complete linux source to boot in /usr/src? All of these irrelevant directories live in /usr The total of my /usr/bin, lib and lib64 (1.4G, 1.3G 3.2G) can easily live in the 9.7G free of my root. It's the rest of /usr that you are pulling along. If you want /usr/bin/lib/lib64 on root... why not just move them there? I split /usr and root because I don't need 20G of docs or fonts or source on my boot disk. Why would you claim that's the only viable answer you could come up with? Moreover, what is there on initrd that you can't put in root? -------- End Original Message -------- On 2021/02/25 13:28, Neal Gompa wrote:
there is an openSUSE specific advantage: A singular /usr tree can be snapshotted trivially with all OS contents together, which simplifies system rollbacks and synchronization of OS content via Btrfs send/recv.
Except for the actual OS (kernel), and libs in /lib, and /lib64(mostly same as /usr/lib64), and /etc/ and state in /var. As well as things living in /opt (a bind-mount to /home/opt on my system)
With /bin being a symlink to /usr/bin, everything should work the same anyway. It's transparent to scripts. It works this way in Fedora, Ubuntu, macOS, Solaris, and others too.
Symlinks aren't transparent. Mounts (and bind-mounts) are. /usr/bin can be mounted from /bin on boot but not the other way around. You can't cleanly snapshot /usr if it is part of the rootfs. But I've had 3rd party SW Virtual Box refuse to run with a symlink in the path.