Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Hello, and you can enable verification of udev rule processing with lvm.conf option: verify_udev_operations = 1 after setting this, I got the following message from lvremove: Node /dev/mapper/vg-lv15-real was not removed by udev. Falling back to direct node removal. Regards Christoph ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Hello, So are you actually trying to access not a 'normal' LV - but an LV under snapshot ? No, /dev/vg/lv20 is a normal logical volume. But /dev/vg/lv15 has been under snapshot before. Now, I created a snapshot manually (before. it was created by an automatic backup mechanism) and saw what happened: 1. I created the snapshot with 'lvcreate -s -L 2G /dev/vg/lv15' 2. Afterwards, a symbolic link /dev/vg/lvol0 existed and pointed to /dev/dm-21. Additionally, a link /dev/mapper/vg-lv15-real existed, pointing to /dev/dm-19 3. I deleted the snapshot with lvremove 4. Afterwards, /dev/vg/lvol0 had disappeared. /dev/mapper/vg-lv15-real was still present, and it did not point to /dev/dm-19 any more, but to /dev/dm-18, the same as /dev/vg/lv20 Regards Christoph ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Dne 13. 08. 19 v 23:25 Bernd Eckenfels napsal(a): Hello, I did not know dmsetup works with lvm file names, did you try to run `dmsetup ls` to see the known devices and the dm compatible name? Hi Of course it has to work. lvm2 names are just symlinks to /dev/dm-XXX real device nodes. If symlinks are missing - something is broken in the setting configuration... Regards Zdenek ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Dne 14. 08. 19 v 9:22 Christoph Pleger napsal(a): Hello, I have a volume group with 20 logical volumes. Only the last one of these volumes has a strange problem with dmsetup, shown by these commands and output on the command line: root@host:/home/linux# /sbin/dmsetup info -c -o name --noheadings /dev/vg/lv20 Device does not exist. Command failed root@host:/home/linux# lvdisplay -c /dev/vg/lv20 /dev/vg/lv20:vg:3:1:-1:0:4194304:512:-1:0:-1:253:19 root@host:/home/linux# mount /dev/vg/lv20 /mnt root@host:/home/linux# ls /mnt lost+found data1 data2 That is, dmsetup says "Device does not exist" about a logical volume, though the volume exists and is operating normally. What is the possible problem here? Have you tried strace ? I attached the relevant lines of the strace output. I am really wondering what is happening there: 1. A stat() on /dev/mapper/lv20 is performed, though I requested /dev/mapper/vg-lv20 2. A stat() on/dev/mapper/vg-lv15-real is performed. What does this have to do with lv20 (after I wrote what is at number 3, I know) 3. I do not even know where /dev/mapper/vg-lv15-real is coming from. I created a logical volume named lv15, but none named lv15-real. And really, 'ls -l /dev/vg/' does not list lv15-real, but 'ls -l /dev/mapper' lists vg-lv15-real and shows that is has the same link target /dev/dm-18 as lv20. 4. Though stat() found /dev/mapper/vg-lv15-real, ioctl() says that this device does not exist. Kernel version, lvm version, distribution... ? Kernel Debian amd64 4.9.168-1+deb9u2, LVM version 2.03.02(2), Debian 9 (stretch) Hi So are you actually trying to access not a 'normal' LV - but an LV under snapshot ? Debian is using it's own modified udev-rules - so I can't really tell without exactly looking what sort of rules are running there. You can try to provide 'lvchange -ay' debug trace when you activate such LV and you can enable verification of udev rule processing with lvm.conf option: verify_udev_operations = 1 That should 'create' missing links if they were not created by udev. NOTE: this is a cruel hack - nothing I'd advice to use normally - since udev rules should handle this case normally - but it can give us some hints, where the issue could be buried-in. So try above steps and check if the LV links are in /dev/vgname dir. Regards Zdenek ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Hello, I did not know dmsetup works with lvm file names, did you try to run `dmsetup ls` to see the known devices and the dm compatible name? Gruss Bernd -- http://bernd.eckenfels.net Von: linux-lvm-boun...@redhat.com im Auftrag von Zdenek Kabelac Gesendet: Dienstag, August 13, 2019 3:54 PM An: LVM general discussion and development; Christoph Pleger Betreff: Re: [linux-lvm] dmsetup says "Device does not exist", though it exists Dne 13. 08. 19 v 9:11 Christoph Pleger napsal(a): > Hello, > > I have a volume group with 20 logical volumes. Only the last one of these > volumes has a strange problem with dmsetup, shown by these commands and output > on the command line: > > root@host:/home/linux# /sbin/dmsetup info -c -o name --noheadings /dev/vg/lv20 > Device does not exist. > Command failed > > root@host:/home/linux# lvdisplay -c /dev/vg/lv20 > /dev/vg/lv20:vg:3:1:-1:0:4194304:512:-1:0:-1:253:19 > > root@host:/home/linux# mount /dev/vg/lv20 /mnt > root@host:/home/linux# ls /mnt > lost+found data1 data2 > > That is, dmsetup says "Device does not exist" about a logical volume, though > the volume exists and is operating normally. What is the possible problem > here? > Hi Have you tried strace ? Are you using this only in singly machine with properly running udev ? Kernel version, lvm version, distribution... ? Zdenek ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] dmsetup says "Device does not exist", though it exists
Hello,
I have a volume group with 20 logical volumes. Only the last one of
these volumes has a strange problem with dmsetup, shown by these
commands and output on the command line:
root@host:/home/linux# /sbin/dmsetup info -c -o name --noheadings
/dev/vg/lv20
Device does not exist.
Command failed
root@host:/home/linux# lvdisplay -c /dev/vg/lv20
/dev/vg/lv20:vg:3:1:-1:0:4194304:512:-1:0:-1:253:19
root@host:/home/linux# mount /dev/vg/lv20 /mnt
root@host:/home/linux# ls /mnt
lost+found data1 data2
That is, dmsetup says "Device does not exist" about a logical volume,
though the volume exists and is operating normally. What is the
possible problem here?
Have you tried strace ?
I attached the relevant lines of the strace output. I am really
wondering what is happening there:
1. A stat() on /dev/mapper/lv20 is performed, though I requested
/dev/mapper/vg-lv20
2. A stat() on/dev/mapper/vg-lv15-real is performed. What does this have
to do with lv20 (after I wrote what is at number 3, I know)
3. I do not even know where /dev/mapper/vg-lv15-real is coming from. I
created a logical volume named lv15, but none named lv15-real. And
really, 'ls -l /dev/vg/' does not list lv15-real, but 'ls -l
/dev/mapper' lists vg-lv15-real and shows that is has the same link
target /dev/dm-18 as lv20.
4. Though stat() found /dev/mapper/vg-lv15-real, ioctl() says that this
device does not exist.
Kernel version, lvm version, distribution... ?
Kernel Debian amd64 4.9.168-1+deb9u2, LVM version 2.03.02(2), Debian 9
(stretch)
Regards
Christophioctl(3, DM_VERSION, {version=4.0.0, data_size=16384, flags=DM_EXISTS_FLAG} =>
{version=4.35.0, data_size=16384, flags=DM_EXISTS_FLAG}) = 0
stat("/dev/vg/lv20", {st_mode=S_IFBLK|0660, st_rdev=makedev(253, 18), ...}) = 0
stat("/dev/mapper/lv20", 0x7ffd1b0ce0d0) = -1 ENOENT (No such file or directory)
open("/dev/mapper", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 4
fstat(4, {st_mode=S_IFDIR|0755, st_size=460, ...}) = 0
getdents(4, /* 23 entries */, 32768)= 992
stat("/dev/mapper/vg-lv15-real", {st_mode=S_IFBLK|0660, st_rdev=makedev(253,
18), ...}) = 0
close(4)= 0
ioctl(3, DM_DEV_STATUS, {version=4.0.0, data_size=16384, name="vg-lv15-real",
flags=DM_EXISTS_FLAG} => {version=4.35.0, data_size=16384, name="vg-lv15-real",
flags=DM_EXISTS_FLAG}) = -1 ENXIO (No such device or address)
write(2, "Device does not exist.", 22Device does not exist.) = 22
write(2, "\n", 1
) = 1
write(2, "Command failed.", 15Command failed.) = 15
write(2, "\n", 1
) = 1
close(3)= 0
exit_group(1) = ?
+++ exited with 1 +++
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