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Re: from / to /usr/: a summary

On Thu, 22 Dec 2011 22:07:21 +1100, Russell Coker <russell@coker.com.au> wrote:
> On Thu, 22 Dec 2011, Goswin von Brederlow <goswin-v-b@web.de> wrote:
> > You only ever NEED stuff from outside LVM if you want to remove the VG
> > the system is on, which makes sense, or if you screwed up. E.g. when you
> > shrink the root LV without having shrunk the filesystem first and need
> > to undo that. At that point it becomes usefull to have access to the lvm
> > backup data, which is kind of hard if it is on lvm. If one has no
> > partition outside of LVM it is a good idea to copy a set of backup
> > metadata to an usb stick, just in case.
> If someone is concerned about possible LVM issues affecting the root 
> filesystem then the easy solution is to just have the root filesystem 
> (including /usr) outside LVM.  The root filesystem isn't one that generally 
> needs to be resized etc and even when /usr is included it's not particularly 
> big by today's standards.
> It seems to me that wanting to have / outside LVM but /usr inside LVM is a 
> fairly obscure corner case.  If we are going to have to hack things to work 
> differently from Fedora (and maybe miss some features along the way) to 
> support such things then I think we shouldn't bother.

I agree, it's an obscure corner case, except for one tiny fact, which is
that it is the way I've been setting servers up for years, which means
that if I want those servers to continue to be as useful as they are now
I'll need to reinstall all of them eventually because of this change.

I was going to say that even my laptop is like that at present, although
I note that in a moment of madness I seem to have let / be put on LVM
for some reason, as you can see:

phil@poker:~$ df -h
Filesystem            Size  Used Avail Use% Mounted on
                      485M  257M  204M  56% /
tmpfs                 1.9G     0  1.9G   0% /lib/init/rw
varrun                1.9G  660K  1.9G   1% /var/run
varlock               1.9G     0  1.9G   0% /var/lock
udev                  1.9G  348K  1.9G   1% /dev
tmpfs                 1.9G     0  1.9G   0% /dev/shm
/dev/sda1             228M   73M  143M  34% /boot
                       34G   32G  277M 100% /home
                      6.9G  6.5G  137M  98% /usr
                      7.7G  6.1G  1.3G  84% /var
                      5.0G  327M  4.4G   7% /srv
                      9.9G  7.9G  1.5G  85% /philmail
                       25G   16G  7.7G  68% /var/www/debian
tmpfs                 2.0G   15M  2.0G   1% /tmp
/dev/ram1              23K   20K  3.0K  87% /home/phil/nobackup/.ram1

Amusingly, I just had to add another 500M to /usr in order to get that
listing to not show 100% for /usr, which I only noticed because I
decided to paste it here, so there you go for the need for resizing /usr
being a rarity :-)

Clearly I don't really care about the laptop, as demonstrated by the
fact that I didn't remember that / was on LVM until I looked, but that's
probably a fair compromise as I'm never going to need to do remote
repairs on it, an I _might_ run out of room on / since I play with new
software there -- on the servers the reverse is the case.

Cheers, Phil.
|)|  Philip Hands [+44 (0)20 8530 9560]    http://www.hands.com/
|-|  HANDS.COM Ltd.                    http://www.uk.debian.org/
|(|  10 Onslow Gardens, South Woodford, London  E18 1NE  ENGLAND

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