Subject: Re: [vserver] Oddity with df
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Tue, 15 May 2012 22:28:20 +0200

On Tue, May 15, 2012 at 08:53:41PM +0100, Phil Daws wrote:
> Well under CentOS6 it looks like /etc/rc.sysinit wipes out
> /etc/mtab and re-populates it with data from /proc/mounts. Any
> thoughts on the best way to handle this so that:

data from /proc/mounts should be fine with a recent kernel

> /dev/hdv1 / ext2 rw 0 0

> would get pulled in ? 

> I have tried creating a guest mtab under
> /etc/vservers/<guest>/apps/init and by adding straight into
> fstab but no joy :(

as you already stated/concluded, util-vserver populates
/etc/mtab correctly, which is then removed by your sysinit
script (which is probably useless anyway). at this point
util-vserver is not involved in the guest startup anymore.
of course, you can start a time delayed script or fix the
rc.sysinit to do the right thing ...

best,
Herbert

> -- 
> Thanks, Phil

> ----- Original Message -----
>> Hmmm, the plot thickens.  Out of curiosity I shut down the guest and
>> removed the init file /etc/vservers/<guest>/apps/init/style which
>> contained the text plain.  Now when I start the guest it complains
>> about upstart issues:

>> initctl: Unable to connect to Upstart: Failed to connect to socket
>> /com/ubuntu/upstart: Connection refused
>> initctl: Unable to connect to Upstart: Failed to connect to socket
>> /com/ubuntu/upstart: Connection refused

>> but when I check /etc/mtab the hdv is indeed there.  When you specify
>> plain in the style file how does that alter the boot process as it
>> appears to be wiping out what is in /etc/mtab ?
>> --
>> Thanks, Phil

>> ----- Original Message -----
>>> Hi Herbert,

>>> Agreed. I shutdown the guest and then ran a simple script which cat
>>> /vservers/guest/etc/mtab into another file. I then started the
>>> guest
>>> and checked the log file for hdv1 and saw:

>>> /dev/hdv1 / ufs defaults 0 0
>>> none /proc proc defaults 0 0
>>> none /tmp tmpfs size=128m,mode=1777,nosuid,nodev,noexec 0 0
>>> none /dev/pts devpts gid=5,mode=620 0 0

>>> then I bit further down it changed too:

>>> none / none rw 0 0

>>> Oh this is going to be a real pain to track down as I do not see
>>> anything in /etc/init.d or the upstart configuration files :(
>>> --
>>> Thanks, Phil

>>> ----- Original Message -----
>>>> On Tue, May 15, 2012 at 07:37:34PM +0100, Phil Daws wrote:
>>>>> Hi Herbert,

>>>>> When you mentioned about the debug option I did look through it
>>>>> and checked that file:

>>>>> [root@testvserver01 ~]# cat /lib/util-vserver/defaults/mtab
>>>>> /dev/hdv1 / ufs defaults 0 0

>>>>> I also checked the other ones in the findObject call and they
>>>>> did not exist. Strange eh ?

>>>> not at all, just means that my original assumption is correct
>>>> and something _inside_ your guest removes the file on startup

>>>> HTH,
>>>> Herbert

>>>>> --
>>>>> Thanks, Phil

>>>>> ----- Original Message -----
>>>>>> On Tue, May 15, 2012 at 06:48:47PM +0100, Phil Daws wrote:
>>>>>>> Hi Herbert,

>>>>>>> Here is the debug file.

>>>>>> so, what does your /lib/util-vserver/defaults/mtab contain?

>>>>>> best,
>>>>>> Herbert

>>>>>>> --
>>>>>>> Thanks, Phil

>>>>>>> ----- Original Message -----
>>>>>>>> On Tue, May 15, 2012 at 06:03:34PM +0100, Phil Daws wrote:
>>>>>>>>> Hi Herbert,

>>>>>>>>> Not that I am aware of. Using the scientific image I built
>>>>>>>>> a
>>>>>>>>> CentOS6 one and changed the repo URLs. That is all which
>>>>>>>>> has
>>>>>>>>> been done.

>>>>>>>> well, the guest's mtab is written by util-vserver, so the
>>>>>>>> version would be interesting, also mtab can be overridden
>>>>>>>> by guest config entries (default and guest specific) which
>>>>>>>> might be the case here as well, finally a --debug guest
>>>>>>>> start might shed some light on this issue ...

>>>>>>>> best,
>>>>>>>> Herbert

>>>>>>>>> --
>>>>>>>>> Thanks, Phil

>>>>>>>>> ----- Original Message -----
>>>>>>>>>> On Tue, May 15, 2012 at 05:51:13PM +0100, Phil Daws wrote:
>>>>>>>>>>> Hmmm, trawling around it would appear I should see
>>>>>>>>>>> something
>>>>>>>>>>> like /dev/hdv1 / ext2 rw 0 0 in /etc/mtab. If I check and
>>>>>>>>>>> older
>>>>>>>>>>> vserver system I do see that but not on the latest
>>>>>>>>>>> release.
>>>>>>>>>>> Has something changed in util-vserver where that does not
>>>>>>>>>>> automatically get added now ?

>>>>>>>>>> IIRC, newer systems switched to /etc/mtab being a link
>>>>>>>>>> to /proc/mounts (which should work fine) so maybe your
>>>>>>>>>> setup removes/clears out /etc/mtab inside the guest?

>>>>>>>>>>> --
>>>>>>>>>>> Thanks, Phil

>>>>>>>>>>> ----- Original Message -----

>>>>>>>>>>>> Hello,

>>>>>>>>>>>> within our test lab I am trying out 3.2.15-vs2.3.2.8 and
>>>>>>>>>>>> a
>>>>>>>>>>>> few CentOS6 clients. Now that the upstart issues have
>>>>>>>>>>>> been
>>>>>>>>>>>> resolved all are looking pretty good. One oddity I have
>>>>>>>>>>>> noticed is that when I perform a 'df' from within a
>>>>>>>>>>>> guest
>>>>>>>>>>>> the
>>>>>>>>>>>> response is:

>>>>>>>>>>>> df: no file systems processed

>>>>>>>>>>>> is there a new capability flag I am missing ?

>>>>>>>>>> not that I know of ...

>>>>>>>>>> best,
>>>>>>>>>> Herbert

>>>>>>>>>>>> --
>>>>>>>>>>>> Thanks, Phil