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
Christoph
ioctl(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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