Re: [gentoo-user] Gentoo LVM Newbie Question

[Boyd Stephen Smith Jr.]

On Monday 27 February 2006 23:01, Zac Slade <krakrjak@××××××××××.net> wrote 
about 'Re: [gentoo-user] Gentoo LVM Newbie Question':
> On Monday 27 February 2006 00:48, Dirk Heinrichs wrote:
> > Wrong. Switch to runlevel 1 (using "telinit 1"), which is for
> > maintenance. In RL 1, no user processes are running and you can umount
> > everything except /.

Also, some maintenance tasks can be run when a filesystem is mounted 
read-only that can't be run when a filesystem is mounted read-write.  So, 
you may be able to do some tasks without disturbing the system as much as 
a init 1 will do.

> Partially right.  Gentoo has several gotchas in runlevel 1.  If /usr is
> a seperate filesystem you have to be careful.

Also, I've had init scripts leave things open in both /usr and /var, but 
these stragglers can be killed simply:
fuser -mv <mount_point> # to list
fuser -mk <mount_point> # to kill

In my experience the processes killed will be either recreated when the 
service is restarted, or were not actually required for any service.

> Bash by default is not
> statically linked and requires readline (which is installed in
> /usr/lib).

Used to be a problem, isn't anymore.  My bash is no longer linked to 
readline at all, and readline has been moved to /lib:

# ls -l /lib/*readline*
lrwxrwxrwx 1 root root     16 Feb 24 09:11 /lib/libreadline.so -> 
libreadline.so.5
lrwxrwxrwx 1 root root     18 Feb 24 09:11 /lib/libreadline.so.5 -> 
libreadline.so.5.1
-rwxr-xr-x 1 root root 246528 Feb 24 09:11 /lib/libreadline.so.5.1

> ls will require libgpm which is also in /usr/lib.

This was a bug at one time, but IIRC, has been fixed.  My ls no longer 
links to gpm at all, and gpm has been moved to /lib:

# ls -l /lib/*gpm*
lrwxrwxrwx 1 root root    11 Feb 24 08:01 /lib/libgpm.so -> libgpm.so.1
lrwxrwxrwx 1 root root    16 Feb 24 08:01 /lib/libgpm.so.1 -> 
libgpm.so.1.19.0
-rwxr-xr-x 1 root root 24160 Feb 24 08:01 /lib/libgpm.so.1.19.0

IMO, finding a binary in /bin or /sbin that links to a library in /usr 
(including /usr/local etc.) is probably grounds for a bug report, even if 
it's not currently causing any problems.

> So you
> have to be careful. One of the best things you can do for yourself is
> install an all in one shell for maintenece like busybox or nash.

This is a good idea, even if none of your particular examples are 
problematic.  The crux of your argument is valid: some very useful 
programs reside in /usr or use libraries in /usr so when trying to umount 
it you must be prepared to do without those programs.

> lvm is not statically linked and can require libraries out of /usr/lib
> also.

lvm2 is static by default, but I have enabled the "nolvmstatic" USE flag. 
This is in contrast to /other/ programs, like mdadm, which are just as 
important but only statically linked is the "static" USE flag is on.

Why the developers decided this crazy behavior is acceptable is a mystery 
to me.  IMO, lvm2 should just be using the static use flag like all the 
other packages.

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh
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