On Wed, Jul 08, 2020 at 09:01:14PM -0700, Ian Zimmerman wrote:
> On 2020-07-07 12:20, Steve Litt wrote:
>
> > You need certain executables, pre-mount, before a separate /usr can be
> > mounted. These went in /sbin, which is on the root and always
> > available. If you could mount the root partition, you could proceed.
> >
> > But now, if you mount /usr somewhere off the root, and simply have
> > /sbin symlink to it, those executables aren't available right away.
> > Imagine if you need the mount executable to mount /usr, but the mount
> > executable *is* on /usr. Buried shovel. The only way around it is to
> > do the mounts in initramfs.
>
> Of course I know all of this. And I guess strictly speaking it *is* an
> answer to my question: if you had this setup and suddenly, without
> notice, you got switched to a "merged" world, you'd be hosed until you
> built an initramfs.
>
> But that is not how in fact it happens: you have plenty of notice, and
> plenty of time to change to a scheme with /usr within the root
> filesystem. And then you don't need an initramfs again, at least not for
> the above reason.
>
> So maybe the real question is, in the merged world, do you have a reason
> to insist on /usr being a mount point, other than tradition? I know that
> people used to do rescue tasks via a single-user boot with only the
> rootfs mounted, but for a long time now it is far easier to do such
> things by booting into some kind of "live" system on a USB stick. One
> can make the live system minimal if so inclined, and in fact the minimal
> Devuan live system is just about perfect for this purpose.

I had to demerge my /usr partition when the contents of my root
partition became too large for space available on its partition and
neighbouring partitions made it difficult to enlarge it.

I expect other admins have other reasons.

-- hendrik

>
> --
> Ian
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