[CentOS] Any alternative to Single User Mode

jd1008 jd1008 at gmail.com
Mon Jun 15 15:43:57 UTC 2015 


On 06/14/2015 10:48 PM, Animesh Pandey wrote:
> On Mon, Jun 15, 2015 at 12:33 AM, jd1008 <jd1008 at gmail.com> wrote:
>
>>
>> On 06/14/2015 10:27 PM, Animesh Pandey wrote:
>>
>>> On Sun, Jun 14, 2015 at 10:51 PM, jd1008 <jd1008 at gmail.com> wrote:
>>>
>>>
>>>> On 06/14/2015 08:02 PM, Animesh Pandey wrote:
>>>>
>>>>   On Sun, Jun 14, 2015 at 9:47 PM, jd1008 <jd1008 at gmail.com> wrote:
>>>>>
>>>>>   On 06/14/2015 07:36 PM, Animesh Pandey wrote:
>>>>>>    On Sun, Jun 14, 2015 at 9:06 PM, jd1008 <jd1008 at gmail.com> wrote:
>>>>>>
>>>>>>>    On 06/14/2015 06:47 PM, Animesh Pandey wrote:
>>>>>>>
>>>>>>>>     I actually opened the Virtual Disk Image (.vdi) on
>>>>>>>>
>>>>>>>>   http://www.vmxray.com/
>>>>>>>>> .
>>>>>>>>> I could see that despite my disk being of 100GB only ~65GB was being
>>>>>>>>> shown.
>>>>>>>>> All the stuff related ot the local user was not visible at all.
>>>>>>>>> After I restarted my VM, the OS gets stuck here (
>>>>>>>>> http://i.stack.imgur.com/KVYxV.png). Even after trying the single
>>>>>>>>> user
>>>>>>>>> login it was stuck there. But the emergency mode worked alright.
>>>>>>>>>
>>>>>>>>> On Sun, Jun 14, 2015 at 8:37 PM, jd1008 <jd1008 at gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>     On 06/14/2015 06:28 PM, Animesh Pandey wrote:
>>>>>>>>>
>>>>>>>>>       Hi,
>>>>>>>>>>    I am working on Centos6.6 on a VirtualBox on Windows Host. Today
>>>>>>>>>> I
>>>>>>>>>>
>>>>>>>>>>> started
>>>>>>>>>>> to have booting issues in the OS. It won't get past the loading
>>>>>>>>>>> screen.
>>>>>>>>>>> I
>>>>>>>>>>> checked and found that the files related to the user "cloudera" on
>>>>>>>>>>> the
>>>>>>>>>>> system were not accessible. Only the files related to root were
>>>>>>>>>>> accessible.
>>>>>>>>>>> This is why I was am not able to do a single user login but an
>>>>>>>>>>> emergency
>>>>>>>>>>> login was possible. This is just a guess.
>>>>>>>>>>> This all happened due to some update in the Virtual Machine that I
>>>>>>>>>>> use
>>>>>>>>>>> to
>>>>>>>>>>> run CentOS.
>>>>>>>>>>>
>>>>>>>>>>> Is there any workaround for this issue?
>>>>>>>>>>>
>>>>>>>>>>> Thanks and regards,
>>>>>>>>>>> Animesh Pandey
>>>>>>>>>>>
>>>>>>>>>>>      I wish you could provide more info.
>>>>>>>>>>>
>>>>>>>>>>>    How can you determine that inaccessibility to a user's
>>>>>>>>>>>
>>>>>>>>>> files will prevent centos from taking you all the way to
>>>>>>>>>> the login (or welcome) screen?
>>>>>>>>>>
>>>>>>>>>> I think something else is going on and my guess is that
>>>>>>>>>> the centos files themselves have been corruped.
>>>>>>>>>> Can you re-install centos ?
>>>>>>>>>>
>>>>>>>>>>     Please do not top-post.
>>>>>>>>>>
>>>>>>>>>>   I am having trouble following your terminology.
>>>>>>>> Emergency model?
>>>>>>>> On my centos installation, there is no "Emergency ...."
>>>>>>>> to select from the list of kernels to boot.
>>>>>>>>
>>>>>>>> Also, when you say "worked alright" do you
>>>>>>>> mean that you were able to access what you thought
>>>>>>>> was missing?
>>>>>>>> Can you go to full multiuser?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>     Sorry for top posting.
>>>>>>>>
>>>>>>>>   Let me give you a clearer idea.
>>>>>>> 1. My regular boot freezes after loading is completed.
>>>>>>> 2. I read on the internet that sometimes due to an update in
>>>>>>> VirtualBox,
>>>>>>> this error might occur. To rectify it, I must re-install VirtualBox's
>>>>>>> Guest
>>>>>>> Additions. For this, I require booting in a Single User Mode.
>>>>>>> 3. For that, I followed the correct steps as given here (
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> https://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-rescuemode-booting-single.html
>>>>>>> ).
>>>>>>> But still the system froze on that same point.
>>>>>>> 4. Then I read about an Emergency mode which is even lower level to
>>>>>>> that
>>>>>>> of
>>>>>>> Single User mode. I was able to log in and see the files that I
>>>>>>> created/modified as root. I could not see any file/folder that related
>>>>>>> the
>>>>>>> local user "cloudera" on which I used to work. This is where I thought
>>>>>>> of
>>>>>>> seeing the contents of the Image using vmxray.com and found that a
>>>>>>> large
>>>>>>> part of the dick is not visible. This part contains that files related
>>>>>>> to
>>>>>>> "cloudera". I felt as if any information related to "cloudera" user
>>>>>>> has
>>>>>>> been lost.
>>>>>>>
>>>>>>> I basically need to access files that I made as "cloudera" on CENTOS
>>>>>>> and
>>>>>>> if
>>>>>>> possible re-install the Guest Additions that ma solve this issue. But
>>>>>>> for
>>>>>>> this I need to be able to boot as a Single User.
>>>>>>>
>>>>>>>    I assume you are using a virtual drive, which is a file on the host
>>>>>>>
>>>>>> machine (You said windows??? ).
>>>>>> If you can somehow use a tool to dump that disk image to
>>>>>> a real hard drive (for example using dd ), and connect
>>>>>> the hard drive a a working linux computer to run fsck on it
>>>>>> to see what it will find.
>>>>>> I assume you have no backup of your drive???
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> CentOS mailing list
>>>>>> CentOS at centos.org
>>>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>>>
>>>>>>    Yes it is windows. By dumping a disk image do you mean a VDI
>>>>>> (VirtualBox
>>>>>>
>>>>> Disk Image). These are files that are used by VirtualBox for booting. I
>>>>> have a copy of that as well. Can Gparted be used for connecting that
>>>>> VDI?
>>>>>
>>>>>    You will more than likely need a conversion tool to convert a vdi
>>>>>
>>>> image to a normal HD image. I do not know of such a tool.
>>>>
>>>> Another possibility is to create another VM, install your linux on it
>>>> with it's own separate disk, but add you bad vdi disk
>>>> as a second drive. Once booted, use linux to fsck the second
>>>> drive.
>>>> Again, be sure you have a copy it before you connect it to this
>>>> new VM.
>>>>
>>>>
>>>> _______________________________________________
>>>> CentOS mailing list
>>>> CentOS at centos.org
>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>
>>>>   I did exactly as you said. I used Gparted to create a secondary drive. I
>>> can do "/dev/" to see the four partitions that my original VM had. How do
>>> I
>>> go about it now?
>>>
>> So, the drive (you want to fix) is visible in the new vm.
>> Good.
>> be sure it is unmounted.
>> As root, run fsck /dev/sd?
>> You supply the value of ?
>> Is it b or c ...?
>>
>> fsck could end up deleting files or even truncating them
>> to shorter lengths if blocks that belong to those
>> files are no longer referenced in the file's inode.
>>
>> Good luck
>>
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>>
> This is how it looks as of now:
> When running "fdisk -l", I get this <http://i.imgur.com/UFp7DOw.png>.
>
> "fsck" results in this <http://i.imgur.com/3TnDMEq.png>
Well, I think you misunderstood what I asked you to try.
/dev/sda should be your VM's 'new' drive you would have created
for the new VM.
And I asked you to attach a copy of the bad drive as a second disk
which Linux would see as /dev/sdbb
In otherwords, you boot from the new drive on which you installed
a fresh installation of Centos.
Once booted, then you fsck the partitions or volumes of /dev/sdb

That will reveal to you what problems you are having with the bad drive
when you fsck those partitions or vol groups.

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