Re: [gentoo-user] separate / and /usr to require initramfs 2013-11-01

[Gregory Shearman]

In linux.gentoo.user, Tanstaafl wrote:
> On 2013-09-29 4:09 PM, Alan McKinnon <alan.mckinnon@×××××.com> wrote:
>> On 29/09/2013 19:59, Tanstaafl wrote:
>>> I've been told that this shouldn't be a big deal... while I am a
>>> (barely) passable linux sys admin
>>
>> Allow me to forward an opinion. The above is not true, not even close.
>>
>> Don't knock yourself, you don't deserve it :-)
>
> Lol!!! At first I thought you were saying that it wasn't true that
> merging /usr into / shouldn't be a big deal - and I was about to start
> gnashing my teeth (again).
>
> Thanks Alan, your words are very kind... and I'll just leave it at
> that... ;)

I've just changed one of my machines so that /usr is now part of the
root filesystem. Like you, I had a separate /usr filesystem. Unlike you
I've been running an initramfs for many years because:

a) I'm running laptops and like them to have pretty graphical boot
screens and no "ugly writing" appearing during the boot sequence. It's
silly, I know, but it still looks pretty. The initramfs will start up
"bootsplash" 8-)

b) The important reason I need an initramfs is that I have my root
filesystems on LVM partitions (except for my ARM servers). I've never
has a scrap of trouble with the genkernel initramfs builds, despite
myriad updates over the years. I've had minor niggles with display but
nothing critical.

So while I've run an initramfs for many years, now it has had to mount
/usr before the "pivot_root" command. This has led to the problem that
/usr is no longer able to be fscked because it is already mounted, and I
cannot for the life of me, get the genkernel initramfs to fsck the /usr
filesystem before mounting. I've had to manually fsck the /usr
filesystem by running my minimal install CD. There are probably ways to
do this (like fscking /usr on shutdown, which I couldn't get working)
but I'm sick of looking for them. I've bit the bullet and changed things
over. It went without a hitch.

Here's what I did:

I added a new LVM volume group and added a "slash" filesystem (10Gb), a
"usrsrc" filesystem for my kernels (10Gb), a "portage" filesystem (3Gb),
a "distfiles" filesystem (15Gb) and a "packages" filesystem (10Gb).
Because these are on LVM they can be adjusted upwards or downwards
depending on usage. I updated /etc/default/grub so that the new kernel
command line will find my new "slash" LVM volume, and ran the grub2
installer to make the change valid.

I then shut down the machine, booted my minimal install CD, used LVM to
find my filesystems. I then mounted my new "slash" and mounted the new
filesystems.

I also decided to move portage, distfiles and packages to the old /var
partition but to do so I first had to mount them in their old positions
on /usr/portage /usr/portage/distfiles etc... Once done, I mounted the
old "slash" and the old "/usr" (with included distfiles and packages and
portage) then did the "cp -av <old hierarchy> <new hierarchy>". It was
then possible to unmount distfiles, packages and portage and then move
them to /var (mount /var and mkdir /var/portage /var/distfiles and
/var/packages) I altered the new "slash" fstab. I then rebooted without
a hitch. Oh, I also had to update /etc/portage/make.conf and the
"make.profile" symlink to reflect the change.

It seems complicated but every step was logical. Having my root
filesystem on LVM has made the change more complicated than it should
have been, but it still was quite easy to do and downtime was minimal.

I don't feel like I've been "forced" to do anything. I'm grateful for
the Gentoo devs and their hard work over the years. This upstream change
is just a small bump in the long Gentoo road. If I didn't agree with the
change then it would be up to me to find a way to get my system to work
without an initramfs, not the Gentoo Devs... after all, this IS open
source. Be grateful that the Gentoo Devs are still willing to volunteer
their time building this great distribution.

-- 
Regards,
Gregory.