Hello
after a lvm snapshot creation and a reboot are all logical volumes are missing, only swap is present.
lvcreate -L 5000M -s -n centos_h1-root_snap /dev/mapper/centos_h1-root
lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert centos_h1-root_snap centos_h1 swi-a-s--- 4,88g root 0,00 home centos_h1 -wi-ao---- 15,00g root centos_h1 owi-aos--- 20,00g swap centos_h1 -wi-ao---- 7,62g var centos_h1 -wi-ao---- 1000,00g
after reboot no complete start, dracut console is running:
dracut:# ls /dev/centos_h1/ swap
dmsetup info shows swap only, too
I can reproduce this on 2 different Servers and a Virtual Machine have same behavior.
What do i wrong?
Greetings
Axel
sorry: centos7 "fresh" minimal with a actual update
cat proc/cmdline:
BOOT_IMAGE=/vmlinuz-3.10.0-229.20.1.el7.x86_64 root=/dev/mapper/centos_root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=de_DE.UTF-8 systemd.debug
ls /dev/mapper: centos-swap control
Zitat von Gordon Messmer gordon.messmer@gmail.com:
On 12/02/2015 11:09 AM, Axel Glienke wrote:
after a lvm snapshot creation and a reboot are all logical volumes are missing, only swap is present.
What release is that? And what does /proc/cmdline contain when the system boots to the dracut shell? _______________________________________________ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Grüße
Axel
Creating snapshot:
[root@lvmtest ~]# lvcreate -L5G -s -n root_snap /dev/centos/root Reducing COW size 5,00 GiB down to maximum usable size 2,94 GiB. Logical volume "root_snap" created. [root@lvmtest ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos owi-aos--- 2,93g root_snap centos swi-a-s--- 2,94g root 0,00 swap centos -wi-ao---- 1,00g
--- reboot ---
dracut shell (missing /dev/centos/root)
cat proc/cmdline: BOOT_IMAGE=/vmlinuz-3.10.0-229.20.1.el7.x86_64 root=/dev/mapper/centos_root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=de_DE.UTF-8 systemd.debug
ls /dev/mapper: centos-swap control
Grüße
Axel
On Wed, Dec 02, 2015 at 08:53:39PM +0100, Axel Glienke wrote:
Creating snapshot:
[root@lvmtest ~]# lvcreate -L5G -s -n root_snap /dev/centos/root Reducing COW size 5,00 GiB down to maximum usable size 2,94 GiB. Logical volume "root_snap" created. [root@lvmtest ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos owi-aos--- 2,93g root_snap centos swi-a-s--- 2,94g root 0,00 swap centos -wi-ao---- 1,00g
--- reboot ---
dracut shell (missing /dev/centos/root)
cat proc/cmdline: BOOT_IMAGE=/vmlinuz-3.10.0-229.20.1.el7.x86_64 root=/dev/mapper/centos_root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=de_DE.UTF-8 systemd.debug
shouldn't you have a new grub entry with: root=/dev/mapper/root_snap rd.lvm.lv=centos/root_snap
Tru
in journalctl i found: modprobe: FATAL: Module dm-snapshot not found ... Can't process LV root_snap: snapshot target support missing from kernel
Zitat von Tru Huynh tru@centos.org:
On Wed, Dec 02, 2015 at 08:53:39PM +0100, Axel Glienke wrote:
Creating snapshot:
[root@lvmtest ~]# lvcreate -L5G -s -n root_snap /dev/centos/root Reducing COW size 5,00 GiB down to maximum usable size 2,94 GiB. Logical volume "root_snap" created. [root@lvmtest ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos owi-aos--- 2,93g root_snap centos swi-a-s--- 2,94g root 0,00 swap centos -wi-ao---- 1,00g
--- reboot ---
dracut shell (missing /dev/centos/root)
cat proc/cmdline: BOOT_IMAGE=/vmlinuz-3.10.0-229.20.1.el7.x86_64 root=/dev/mapper/centos_root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=de_DE.UTF-8 systemd.debug
shouldn't you have a new grub entry with: root=/dev/mapper/root_snap rd.lvm.lv=centos/root_snap
Tru
-- Tru Huynh http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBEFA581B
Grüße
Axel
Ok, kernel needs the module dm-snapshot for snapshot support, but the modules is storage on a snapshoted-lv ...
you can't make a root_snapshot with centos?
Zitat von Axel Glienke axel@glienke.cc:
in journalctl i found: modprobe: FATAL: Module dm-snapshot not found ... Can't process LV root_snap: snapshot target support missing from kernel
Zitat von Tru Huynh tru@centos.org:
On Wed, Dec 02, 2015 at 08:53:39PM +0100, Axel Glienke wrote:
Creating snapshot:
[root@lvmtest ~]# lvcreate -L5G -s -n root_snap /dev/centos/root Reducing COW size 5,00 GiB down to maximum usable size 2,94 GiB. Logical volume "root_snap" created. [root@lvmtest ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root centos owi-aos--- 2,93g root_snap centos swi-a-s--- 2,94g root 0,00 swap centos -wi-ao---- 1,00g
--- reboot ---
dracut shell (missing /dev/centos/root)
cat proc/cmdline: BOOT_IMAGE=/vmlinuz-3.10.0-229.20.1.el7.x86_64 root=/dev/mapper/centos_root ro rd.lvm.lv=centos/root rd.lvm.lv=centos/swap crashkernel=auto rhgb quiet LANG=de_DE.UTF-8 systemd.debug
shouldn't you have a new grub entry with: root=/dev/mapper/root_snap rd.lvm.lv=centos/root_snap
Tru
-- Tru Huynh http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBEFA581B
Grüße
Axel
CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Grüße
Axel
On 12/02/2015 12:05 PM, Axel Glienke wrote:
in journalctl i found: modprobe: FATAL: Module dm-snapshot not found ... Can't process LV root_snap: snapshot target support missing from kernel
I installed a very simple CentOS 7 system with an LVM root FS. Created a snapshot and rebooted, no problem. Updated dracut, then updated everything else and rebooted, no problem.
As far as I can tell, dracut normally includes the entire kernel module tree under kernel/drivers/md, which should provide the dm-snapshot module required to complete the boot sequence.
I can't determine what's causing the problem you see, but it doesn't appear to affect a standard installation.
Try:
dracut --force --debug > /var/tmp/dracut.txt 2>&1
Upload /var/tmp/dracut.txt to http://paste.fedoraproject.org/. I'll see if I spot anything useful.
ok, thank you very much Gordon.
but you know what the difference?
if i do 1. centos7 installation 2. yum upgrade 3. lvcreate -s ... 4. reboot
then i got the error.
if i do your way 1. centos7 installtion 2. snapshot & reboot 3. yum upgrade 4. reboot
then the system start.
Zitat von Gordon Messmer gordon.messmer@gmail.com:
On 12/02/2015 12:05 PM, Axel Glienke wrote:
in journalctl i found: modprobe: FATAL: Module dm-snapshot not found ... Can't process LV root_snap: snapshot target support missing from kernel
I installed a very simple CentOS 7 system with an LVM root FS. Created a snapshot and rebooted, no problem. Updated dracut, then updated everything else and rebooted, no problem.
As far as I can tell, dracut normally includes the entire kernel module tree under kernel/drivers/md, which should provide the dm-snapshot module required to complete the boot sequence.
I can't determine what's causing the problem you see, but it doesn't appear to affect a standard installation.
Try:
dracut --force --debug > /var/tmp/dracut.txt 2>&1
Upload /var/tmp/dracut.txt to http://paste.fedoraproject.org/. I'll see if I spot anything useful. _______________________________________________ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Grüße
Axel
On 12/02/2015 02:02 PM, Axel Glienke wrote:
ok, thank you very much Gordon.
but you know what the difference?
if i do
- centos7 installation
- yum upgrade
- lvcreate -s ...
- reboot
then i got the error.
I'll try to recreate the problem on a new VM, but that doesn't make much sense. Including the required module isn't dependent on creating the snapshot as far as I can tell.
If you can get dracut debug output from an affected system, I might be able to help. Without that, I can't think of anything else I can offer you.
dracut --force --debug > /var/tmp/dracut.txt 2>&1
(Upload /var/tmp/dracut.txt to http://paste.fedoraproject.org/)
On 12/02/2015 02:48 PM, Gordon Messmer wrote:
I'll try to recreate the problem on a new VM, but that doesn't make much sense. Including the required module isn't dependent on creating the snapshot as far as I can tell.
Crazy pants.
I can reproduce the problem now. I don't know what the hell is going on, but I'm still looking.
a manually dracut -f --add-drivers "dm-snapshot" solve the problem
Zitat von Gordon Messmer gordon.messmer@gmail.com:
On 12/02/2015 02:48 PM, Gordon Messmer wrote:
I'll try to recreate the problem on a new VM, but that doesn't make much sense. Including the required module isn't dependent on creating the snapshot as far as I can tell.
Crazy pants.
I can reproduce the problem now. I don't know what the hell is going on, but I'm still looking. _______________________________________________ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Grüße
Axel
LVM is terribly flawed and most imprudent piece of any filesystem that you can have for snapshot'ing!
The only snapshot-friendly filesystem or volume manager is ZFS. Whether create a single snapshot or few hundred thousand. It is instant and no data is lost.
On Thu, Dec 3, 2015 at 12:09 AM, Axel Glienke axel@glienke.cc wrote:
Hello
after a lvm snapshot creation and a reboot are all logical volumes are missing, only swap is present.
lvcreate -L 5000M -s -n centos_h1-root_snap /dev/mapper/centos_h1-root lvs LV VG Attr LSize Pool Origin Data%Meta% Move Log Cpy%Sync Convert centos_h1-root_snap centos_h1 swi-a-s--- 4,88g root 0,00 home centos_h1 -wi-ao---- 15,00g root centos_h1 owi-aos--- 20,00g swap centos_h1 -wi-ao---- 7,62g var centos_h1 -wi-ao---- 1000,00g
after reboot no complete start, dracut console is running:dracut:# ls /dev/centos_h1/ swap
dmsetup info shows swap only, tooI can reproduce this on 2 different Servers and a Virtual Machine have same behavior.
What do i wrong?
Greetings
Axel
CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
https://bugzilla.redhat.com/show_bug.cgi?id=1287940
I'm not sure what I saw that made me think the entire drivers/md tree was included. I deleted the first VM that I used to investigate the problem, so I can't look at the shell history to figure that one out. In any case, that's not what dracut does.
I filed a bug suggesting that dm-snapshot should always be included for systems on LVM.
-
Axel Glienke -
Gordon Messmer -
Micky -
Tru Huynh