CentOS - Jul 2018 - Issues booting centos7 [dracut is failing to enable centos/root, centos/swap LVs]

> Yannis Milios wrote:
>>> But, what happens if you let the kernel post install scripts do the
>>> work or setting up the initrd things?
>>
>> Initially, I just rebooted from LiveCD and left Grub,kernel and dracut
>> do
>>  their job with the defaults, but unfortunately, boot process stops at
>> initrd (dracut) stage with the following error:
>>
>> [  197.768159] localhost.localdomain dracut-initqueue[252]: Warning:
>> Could
>>
>>> not boot. [  197.821409] localhost.localdomain systemd[1]: Received
>>> SIGRTMIN+20 from
>>> PID 254 (plymouthd).
>>> [  197.822328] localhost.localdomain dracut-initqueue[252]:
Warning:
>>> /dev/centos/root does not exist
>>> [  197.823044] localhost.localdomain dracut-initqueue[252]:
Warning:
>>> /dev/centos/swap does not exist
>>> [  197.846807] localhost.localdomain systemd[1]: Starting Dracut
>>> Emergency
>>> Shell...
>>> [  197.870983] localhost.localdomain systemd[1]: Received
SIGRTMIN+21
>>> from PID 254 (plymouthd).
>>>
>>
>>
>> Then, I'm dropped to dracut shell, where I boot the system by using
the
>> lvm commands as described to my first post. Once in O/S, I re-create
>> initrd
>> by using 'dracut -f -v -a lvm' command and reboot again the
system. But
>> still I get the same error during boot ...
>>
>> If you reinstall the latest kernel, does
>>
>>> it change anything?
>>>
>>
>> This is actually the latest kernel (3.10.0-862.9.1.el7.x86_64) but I
>> tried to boot with the second (older) kernel
>> (vmlinuz-3.10.0-327.36.3.el7.x86_64), where I got exactly the same
error
>> during boot.
>>
>> Clearly, this is not a kernel issue, perhaps not even a dracut (initrd)
>> issue, since everything was working fine, before resizing the PV/LV. I
>> suspect that something went wrong during that step, but what? As I can
>> successfully boot the system manually via dracut, normally everything
>> should be ok? no?
>>
>> What can prevent dracut from activating the 2 LVs (centos/root and
>> centos/swap) during initial boot phase ?
>>
> Suggestion: once it's up, rebuild the initramfs.
And when you did so, did you remove the "rd.shell" from
GRUB_CMDLINE_LINUX
before?

Regards,
Simon

And when you did so, did you remove the "rd.shell" from
GRUB_CMDLINE_LINUX
> before?
>
>
Yes, basically that option was not there by default, I added it during the
troubleshootig steps. Normally, rd.lvm.lv=centos/root and rd.lvm.lv=centos/swap
are the kernel parameters which are parsed to dracut for enablig the two
LVs, but somehow dracut does not.

I've copied the log from dracut in here, can this be helpful to locate the
problem?

https://privatebin.net/?fdc4052c0c402884#gdB/QYR3IeR55SxUbjfrkZPQfJ7jMxiUxq5DWhTVbWc



-- 
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Finally, I was able to find a solution for this. I'm posting the result
here, just in case that it's useful for someone else in the future ...

The problem was not in initramfs (dracut), but on the fact that /dev/sda2
partition(PV),  after I resized it, somehow got 2  partition table
signatures.

One was set as a "dos" partition with an offset "0x1fe" and
second set as
"LVM_member" with an offset "0x8e".

This confused blkid in initramfs, during the initial boot stage, thinking
that /dev/sda2 is *not* an LVM_member but rather a simple "dos"
partition,
hence refused to activate centos/root and centos/swap LVs which were
required to boot the machine to the O/S.

What's interesting is that neither fdisk or parted were showing this second
signature, however there was a trace of it in the dracut report file
(/run/initramfs/rdsosreport.txt), specifically the one below..


+ blkid
/dev/sr0: UUID="2016-10-28-12-18-36-00" LABEL="CentOS 7
x86_64"
TYPE="iso9660" PTTYPE="dos"
/dev/sda1: UUID="a620a180-3a8c-4b5f-ad30-804f131a7261"
TYPE="xfs"
/dev/sda2: PTTYPE="dos"
+ blkid -o udev
ID_FS_UUID=2016-10-28-12-18-36-00
ID_FS_UUID_ENC=2016-10-28-12-18-36-00
ID_FS_LABEL=CentOS_7_x86_64
ID_FS_LABEL_ENC=CentOS\x207\x20x86_64
ID_FS_TYPE=iso9660
ID_PART_TABLE_TYPE=dos

To fix the problem, I booted the system from a livecd and used
"wipefs"
utility to erase the problematic signature "dos" and leave only the
correct
one "LVM_member".

The exact command was: 'wipefs -o 0x1fe -ff /dev/sda2'

[root at localhost ~]# blkid
/dev/sr0: UUID="2016-10-28-12-18-36-00" LABEL="CentOS 7
x86_64"
TYPE="iso9660" PTTYPE="dos"
/dev/sda1: UUID="a620a180-3a8c-4b5f-ad30-804f131a7261"
TYPE="xfs"
/dev/sda2: UUID="qBSpoz-i0Zq-AwlP-kviR-leui-L9NA-pcjAg1"
TYPE="LVM2_member"
/dev/mapper/centos-root: UUID="a48af6f8-13d0-4c5d-a772-463b0da63bb1"
TYPE="xfs"
/dev/mapper/centos-swap: UUID="7f1d19db-1719-4fe8-a816-0a038a70ecde"
TYPE="swap"