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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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 Posted: Fri Jan 15, 2021 11:57 am Post subject: [SOLVED] gentoo with root partition on LVM |
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Hi,
I followed the Gentoo LVM Wiki, but I guess I've missed something because I can't mount the root partition when booting.
Some partitions are in MDADM RAID1 and the ROOT partition is in LVM mirror RAID1.
These are some of my relevant steps from livecd:
| Code: | | genkernel --install --mdadm --mdadm-config=/etc/mdadm.conf --lvm initramfs |
I install grub with a line like this one:
| Code: | | linux /${K} root=/dev/ram0 init=/linuxrc ramdisk=8192 rootfstype=ext4 vga=0 domdadm dolvm real_root=/dev/vgroot/root |
The installed system boots, but it fails to find /dev/vgroot/root, so I enter the busybox shell.
I see a message that says that I can copy /run/..something to a USB pendrive, but oddly enough I can't seem to mount the device.
Both lsusb and dmesg show that the device is in /dev/sdc1, but mount/dev/sdc1 /mnt/pendrive says "no such file or directory". Both exist so I don't know what's up.
Anyway, the following commands show what I'm expecting:
| Code: | lvm lvdisplay
lvm pvs |
Specifically, I see /dev/vgroot/root, two mirrored volumes, etc., except for one suspicious line:
| Code: | | LV Status Not available |
In fact, if I reboot in the livecd again, I can see that the status is "available":
| Code: | # lvdisplay
WARNING: Failed to connect to lvmetad. Falling back to device scanning.
--- Logical volume ---
LV Path /dev/vgroot/root
LV Name root
VG Name vgroot
LV UUID qgWICf-J4s1-LozA-RnUL-pMBy-iumd-B1daVw
LV Write Access read/write
LV Creation host, time livecd, 2021-01-08 14:20:45 +0000
LV Status available
# open 0
LV Size 187.12 GiB
Current LE 47904
Mirrored volumes 2
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:4 |
So it seems that I've done something wrong in the initramdisk, right?
What can I try?
Last edited by Vieri on Thu Jan 21, 2021 1:48 pm; edited 1 time in total |
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alamahant
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Joined: 23 Mar 2019
Posts: 3879
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| Posted: Fri Jan 15, 2021 12:13 pm Post subject: |
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Hi
Did you install lvm in the chroot?
The live cd has it installed
but maybe its missing in the chroot.
Also you have to enable lvm@boot and lvmetad@default.
Also I much prefer dracut to genkernel.
Its easier for beginners.
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Fri Jan 15, 2021 12:27 pm Post subject: |
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Hi,
Yes, I emerged lvm2 in the jailed root environment. I also added LVM to the boot runlevel. I did not add lvmetad.
However, the problem is occurring in the initramfs, and the LVM volume information seems to be there.
It's just that the "status" is "unavailable". It may be simply because the initramdisk (genkernel) does not "activate" something at boot time.
Never tried dracut.
I guess I'll have to try.
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54300
Location: 56N 3W
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| Posted: Fri Jan 15, 2021 12:28 pm Post subject: |
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Vieri,
A few things.
There are two ways to do root in a LV on top of raid.
The one I use is to donate the block devices to an mdadm raid set, then donate the raid set to a PV.
This way the underlying raid is not visible to LVM.
The other way in to have LVM do it all. You appear to be doing that as you get
| Code: | # lvdisplay
...
Mirrored volumes 2
... |
The kernel parameters | Code: | | root=/dev/ram0 init=/linuxrc ramdisk=8192 |
have been obsolete for a long time.
The initramfs is no longer a ramdrive and the default init= just works.
When you poke about in the initrd shell, you say everything you expect to see is there.
Can you mount /dev/vgroot/root by hand ?
If not, what is the error?
Is there anything in dmesg?
Busybox does not have less. Use as a pager.
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NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Fri Jan 15, 2021 1:32 pm Post subject: |
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No, /dev/vgroot/root is nowhere to be seen.
However lvm lvdisplay DOES show the "right info" about /dev/vgroot/root except that the LV status is "not available".
I will try to run vgscan and vgchange -a y within that SHELL.
Regarding the grub line, I understand that this would be enough?
| Code: | | linux /${K} root=/dev/ram0 rootfstype=ext4 vga=0 domdadm dolvm real_root=/dev/vgroot/root |
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NeddySeagoon
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Joined: 05 Jul 2003
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Location: 56N 3W
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| Posted: Fri Jan 15, 2021 1:57 pm Post subject: |
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Vieri,
should be enough.
In my install, /dev/vg/ are all symlinks. You need something to create symlinks.
What does tell and/or | Code: | | ls -l /dev/mapper/* |
You are looking for real block device files.
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NeddySeagoon
Computer users fall into two groups:-
those that do backups
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Fri Jan 15, 2021 2:14 pm Post subject: |
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If I enter the SHELL when the boot process complains that the root LVM partition is not there, I can run these commands:
| Code: | lvm vgscan
lvm vgchange -a y |
and that does it. The root partition /dev/vgroot/root is there as well as all the /dev/mapper/* devices.
If I "exit" the SHELL the boot process resumes perfectly, and I can log into my system.
So there's obviously something wrong with the way I created my initramdisk with genkernel. |
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Fri Jan 15, 2021 2:19 pm Post subject: |
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| NeddySeagoon wrote: |
What does tell
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Does not exist.
| NeddySeagoon wrote: |
and/or | Code: | | ls -l /dev/mapper/* |
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Just /dev/mapper/control.
As reported in my previous comment, I solve the issue by running vgchange -ay.
However, now I need to understand why genkernel did not generate a "proper" initramdisk. |
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NeddySeagoon
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Location: 56N 3W
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| Posted: Fri Jan 15, 2021 3:06 pm Post subject: |
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Vieri,
I've not used genkernel, so I can't help further.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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alamahant
Advocate
Joined: 23 Mar 2019
Posts: 3879
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| Posted: Fri Jan 15, 2021 3:46 pm Post subject: |
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In the beginning genkernel used to wrork for me for booting root on lvm.
At some point it stopped.
Then I switched to dracut.
And have never looked back since.
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gentoo_ram
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Joined: 25 Oct 2007
Posts: 475
Location: San Diego, California USA
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| Posted: Sun Jan 17, 2021 1:00 am Post subject: |
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I'm using root on LVM with an initramfs created by genkernel.
Make sure you have LVM="yes" in your /etc/genkernel.conf
I also have these set: E2FSPROGS, BUSYBOX, LUKS, MDADM, DISKLABEL
For my boot string I have:
linux /vmlinuz-5.10.2-gentoo root=/dev/mapper/vg0-root ro rootfstype=ext4 dolvm
echo 'Loading initial ramdisk ...'
initrd /intel-uc.img /initramfs-5.10.2-gentoo.img
The intel-uc.img is for Intel firmware updates. You may or may not need those.
Then 'genkernel initramfs' and 'grub-mkconfig -o /boot/grub/grub.cfg'. |
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skellr
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Joined: 18 Jun 2005
Posts: 976
Location: The Village, Portmeirion
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| Posted: Sun Jan 17, 2021 4:13 pm Post subject: |
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| Yeah, Genkernel initramfs is _deceptively_ easy to use. You don't need to add extra kernel parameters related to the initrd llike real_root=, root=/dev/ram0, or init= as it will break things. just a simple ( root=/dev/vgroot/root dolvm ) should work. |
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Mon Jan 18, 2021 2:01 pm Post subject: |
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OK, thanks, everyone.
I do believe however that there seems to be a bug in the way the init script generated by genkernel actually initializes the volume groups, or maybe it's a kernel "thing". I don't know, but here's what I've observed.
I've booted the kernel from the grub entry that grub-install makes out of 10_linux. All boots fine untl the initramdisk tries to mount the root partition (LVM). It complains that /dev/mapper/vgroot-root does not exist.
Now, if I enter the SHELL manually, I can see that /dev/mapper/ is empty (except for "control") and /dev/vgroot is non-existent. I also see from dmesg that before trying to mount /dev/mapper/vgroot-root the boot process actually did try to initialize LVM volume groups. I see the following:
| Code: | Executed: 'lvm vgscan'
Executed: 'udevadm settle --timeout=120' |
and then:
| Code: | Executed: 'lvm vgchange -ay --sysinit'
Executed: 'udevadm settle --timeout=120'
Executed: 'mkdir -p /newroot' |
Finally:
| Code: | [OK] Determining root device (trying /dev/mapper/vgroot-root) ...
[!!] Block device /dev/mapper/vgroot-root is not a valid root device
[!!] Could not find the root block device in /dev/mapper/vgroot-root |
However, within the "rescueshell" I can manually run:
| Code: | # lvm vgchange -ay --sysinit
1 logical volume(s) in volume group 'vgroot' now active |
Now, both /dev/mapper/ and /dev/vgroot/ contain the devices I'm expecting.
Simply exiting the "rescueshell"resumes the boot process, and my root partition mounts fine bringing me to a login prompt.
So, I guess something screws up at boot time. It might be a timeout, the boot process is too fast, I don't know...
If no one has seen this before I guess I'll have to open a bug report.
Thanks |
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skellr
l33t
Joined: 18 Jun 2005
Posts: 976
Location: The Village, Portmeirion
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| Posted: Mon Jan 18, 2021 2:23 pm Post subject: |
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Maybe rootdelay would help with that.
| Code: | rootdelay[=<...>], rootwait[=<...>]
Pauses for up to 3 seconds (or specified number of seconds) while waiting for root
device to appear during initramfs root scanning.
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Good luck. |
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Tue Jan 19, 2021 10:09 am Post subject: |
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Thanks for the suggestion, but I don't think this will make any difference at all (I'll try it as soon as I get the chance though).
The reason I'm saying this is that the init script that Genkernel generates already does a while loop to wait for the root device, and it seems to me that aprox. 3 seconds should be more than enough.
In any case, even if the while loop breaks and I enter the "rescueshell" manually, a whole lot of time has already passed until I manually inspect /dev/mapper and before I run vgchange -ay again... So no matter how big the delay, the root partition will never show up unless vgchange is run again.
So I'm wondering why the first run within Genkernel's init script failed to bring ROOT up.
Unfortunately, I didn't take a peak at /run/initramfs/init.log when I was in the "rescueshell", and I won't be able to do so for the next two days.
Instead, I ran vgchange -ay manually, exited the shell and finished booting the system as expected.
Now, does anyone know if it's possible to access init.log from the booted system, or has the initramdisk been wiped out of memory?
[EDIT] Maybe the init.log can tell me what went wrong when the init script tried to scan and init the volumes. Also, I might try to use the scandelay= kernel line option. |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54300
Location: 56N 3W
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| Posted: Tue Jan 19, 2021 10:30 am Post subject: |
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Vieri,
The initramfs is abandoned when it exits with the pivotroot command.
The may be a kernel command line parameter to keep it.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
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alamahant
Advocate
Joined: 23 Mar 2019
Posts: 3879
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| Posted: Tue Jan 19, 2021 10:36 am Post subject: |
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Is your /boot a separate partition?
If it is on encrypted lvm then you need to add additional parameters to /etc/default/grub
It is not a good idea to have encrypted or lvm /boot
Maybe add
| Code: |
GRUB_ENABLE_CRYPTODISK=y
GRUB_PRELOAD_MODULES="part_msdos part_gpt luks luks2 lvm"
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Is your /dev/vgroot/root encrypted?
Did you use luks1 or luks2?
Your /boot should ONLY be luks1
Can you please post the output of
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Last edited by alamahant on Tue Jan 19, 2021 10:57 am; edited 1 time in total |
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Tue Jan 19, 2021 10:55 am Post subject: |
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I thought initramfs was gone too. So I guess I'll need to reboot and check init.log to see if I can get something out of it. I will also try to add the scandelay= option, but that will be in a few days.
Meanwhile, the output of blkid (run after running vgchange manually, exiting "rescueshell" and logging in the system) is:
| Code: | # lsblk -fs
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINT
sda2 vfat A483-1682
└─sda
sdb2 vfat A485-1FD7
└─sdb
sdc1 vfat KINGSTON 3C61-F846
└─sdc
md1
├─sda1 linux_raid_member 50191324-5a36-9401-cb20-1669f728008a
│ └─sda
└─sdb1 linux_raid_member 50191324-5a36-9401-cb20-1669f728008a
└─sdb
md3 ext2 e54bbc62-bd17-487a-853a-ed14d0702a71
├─sda3 linux_raid_member a1c952fe-ccf5-ea8d-cb20-1669f728008a
│ └─sda
└─sdb3 linux_raid_member a1c952fe-ccf5-ea8d-cb20-1669f728008a
└─sdb
md4 swap cdb2cd63-f80d-4dc0-b71f-32040e820de2 [SWAP]
├─sda4 linux_raid_member 644f2899-7ab5-22bd-cb20-1669f728008a
│ └─sda
└─sdb4 linux_raid_member 644f2899-7ab5-22bd-cb20-1669f728008a
└─sdb
vgroot-root ext4 f6ad07cc-7a5c-4b62-9783-15f36e9ac00a 158.6G 8% /
├─vgroot-root_rmeta_0
│
│ └─sda5 LVM2_member PySdiK-NJWq-xiDr-vnxV-Eam7-eJ8f-gsGXHn
│ └─sda
├─vgroot-root_rimage_0
│ ext4 f6ad07cc-7a5c-4b62-9783-15f36e9ac00a
│ └─sda5 LVM2_member PySdiK-NJWq-xiDr-vnxV-Eam7-eJ8f-gsGXHn
│ └─sda
├─vgroot-root_rmeta_1
│
│ └─sdb5 LVM2_member xFq6vW-lECT-2VUY-ZqNJ-9tIZ-uC55-dlFbnS
│ └─sdb
└─vgroot-root_rimage_1
ext4 f6ad07cc-7a5c-4b62-9783-15f36e9ac00a
└─sdb5 LVM2_member xFq6vW-lECT-2VUY-ZqNJ-9tIZ-uC55-dlFbnS
└─sdb
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So, yes, /boot is a seperate partition and is in mdadm RAID1.
The ROOT LVM is not encrypted.
No LUKS. |
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alamahant
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Joined: 23 Mar 2019
Posts: 3879
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| Posted: Tue Jan 19, 2021 11:01 am Post subject: |
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Would it be awfully terrible if you created a simple plain no-raid /boot partition and used that instead of the raid one?
Because as I see it you are now struggling with two tricky things instead of one.
/ on raid lvm
and /boot on raid.
Just eliminate the second and see if the first also is rectified.
You will need ofcourse to reinstall and update grub and create a new initramfs.
Maybe you can try entering
| Code: |
GRUB_PRELOAD_MODULES="part_msdos part_gpt mdraid1x lvm"
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in /etc/default/grub
before changing your partitions though....
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Vieri
l33t
Joined: 18 Dec 2005
Posts: 886
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| Posted: Thu Jan 21, 2021 12:46 pm Post subject: |
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The kernel parameter scandelay solved the issue.
If I install grub with the following then all works fine:
| Code: | # grep ^GRUB_CMDLINE_LINUX /etc/default/grub
GRUB_CMDLINE_LINUX="domdadm dolvm scandelay=1" |
Without scandelay=1 (or more) initramfs is unable to start the volume groups. |
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Installing Gentoo
