[arch-general] Partition mounting in systemd [WAS: Lennart Poettering on udev-systemd]

[C Anthony Risinger]

On Wed, Aug 15, 2012 at 12:19 PM, Baho Utot <baho-utot at columbus.rr.com> wrote:
> On 08/15/2012 11:01 AM, C Anthony Risinger wrote:
>>
>> On Wed, Aug 15, 2012 at 6:38 AM, Baho Utot <baho-utot at columbus.rr.com>
>> wrote:
>>>
>>> On 08/14/2012 08:53 PM, Oon-Ee Ng wrote:
>>>>
>>>> On Wed, Aug 15, 2012 at 8:13 AM, Tom Gundersen <teg at jklm.no> wrote:
>>>>>
>>>>> On Wed, Aug 15, 2012 at 1:55 AM, David Benfell
>>>>> <benfell at parts-unknown.org> wrote:
>>>>>>
>>>>>> Does systemd not use the standard
>>>>>> mount program and follow /etc/fstab?
>>>>>
>>>>> It does. Though it does not use "mount -a", but rather mounts each fs
>>>>> separately.
>>>>
>>>>
>>> [putolin]
>>>
>>> I came across another anomaly on my systemd boxes that I would like
>>> someone
>>> to verify if they could.  Please do this on a backup system.
>>>
>>> I was changing some lvm partitions about that were mounted in /etc/fstab,
>>> actually I removed them and created two new lvm partitions with different
>>> names, but failed to update the fstab. Upon rebooting the systems failed
>>> to
>>> boot and where stuck at trying to mount the non existing lvm partitions.
>>> I
>>> could not fix the systems as I could not get a "recovery" bash prompt.  I
>>> had to use a boot live CD to edit the fstab and then all was well. On all
>>> my
>>> sysvinit systems a bad mount point would just give me an error and
>>> continue
>>> booting.
>>>
>>> Could some brave enterprising soul confirm this?
>>>
>>> This created the following question: Can systemd boot a system without a
>>> fstab?
>>
>> you would have to provide the mountpoints -- depending on what you
>> were mounting i'm quite sure initscripts would fail (/usr? /var? what
>> was changed??), though they may very well just keep chugging on,
>> pretending all is well.
>>
>> root mount depends on nothing more than what's listed on the kernel
>> cmdline in grub.cfg or equivalent.  you could have also added
>> `break=y` (legacy form, i forget the new syntax) to open a shell in
>> the initramfs and correct from there.
>>
>> AFAIK systemd doesn't NEED an fstab, but you would then need to
>> provide native *.mount files instead ... SOMETHING has to tell it
>> where the mounts go, yes?
>>
>
> I don't know what your pointing out here

i asked you a question -- i don't know what i'd be pointing out either.

> What I had was /dev/lvm/lfs and /dev/lvm/LFS in the fstab.  These where
> mounted into /mnt/lfs and /mnt/lfs/LFS

/dev/lvm/? (/dev/mapper/?)

> I removed those from lvm and created /dev/lvm/wip and /dev/lvm/WIP and I did
> not remove the /dev/lvm/lfs and /dev/lvm/LFS from the fstab file, then
> rebooted.
>
> As far as I could tell systemd rolled over because it could not mount the
> lfs and LFS lvm partitions, because they where not there.
> It just hung waiting for mount points that just wasn't going to showup no
> matter what.  I could not get a "maintenence prompt" it was just stuck at
> trying to mount the non-existent lvm partitions.

i said it would time out.

i'm not 100% sure why that is considered a system critical mount, but
there is nothing special about your experience, at the very least it's
just  Plain Old Bug, if at all, and providing there are not other
details you've not realized and/or disclosed.

just report/investigate man, and things get better for everyone.

> My sysvinit systems simply spit out an error "can mount what ever blah blah
> blah" and continued to boot. Of course those points were not mounted by the
> system did boot fully.

ok?  my guess is systemd would timeout and move on as well.

> As for booting without an fstab I do that alot on my custom "rescue" usb
> thumb drives as they do not have a fstab file at all.
> I use not *.mount files at all and the system works just fine....the kernel
> knows where its root file system is.
> Try removing/moving the fstab from a test system.  It will boot and run
> fine, of course you will lose swap and any other such things but if you have
> everything on one partition your good.

.... yeah i think i already said something to this effect
(RE:grub.cfg), but `init=/bin/bash` is the painless way to fix in 30
seconds -- if your a badass (which i am, anyway ;-).

-- 

C Anthony