LVM snapshot on Luks encrypted drive?

jm1

New Member
Apr 15, 2012
5
0
1
Hello,

I am trying to make a vzdump on a Luks encrypted drive and I always get the

INFO: mode failure - unable to detect lvm volume group
INFO: trying 'suspend' mode instead

failure message.
I am not 100% sure whether it is actually possible to make a snapshot on an encrypted drive but so far I did not find anything saying that it is impossible.

My configuration looks as following:

vgdisplay:

--- Volume group ---
VG Name pve
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 1
Act PV 1
VG Size 460.15 GiB
PE Size 4.00 MiB
Total PE 117798
Alloc PE / Size 94599 / 369.53 GiB
Free PE / Size 23199 / 90.62 GiB
VG UUID 2uheZe-rjdw-xWMn-ajaB-yaq4-geRl-dv6o2k



lvdisplay:
--- Logical volume ---
LV Name /dev/pve/root
VG Name pve
LV UUID kQKKKW-1HuT-kvJj-AKhD-9oFJ-ZjRW-lZVmBZ
LV Write Access read/write
LV Status available
# open 1
LV Size 9.77 GiB
Current LE 2500
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0

--- Logical volume ---
LV Name /dev/pve/swap
VG Name pve
LV UUID YMx93I-tCR1-1N5A-Bw57-ctbx-Qrib-M2IylQ
LV Write Access read/write
LV Status available
# open 1
LV Size 9.77 GiB
Current LE 2500
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

--- Logical volume ---
LV Name /dev/pve/data
VG Name pve
LV UUID eWc5Ay-RTbq-GS2n-RSau-j1i9-HNGi-mdzVGv
LV Write Access read/write
LV Status available
# open 1
LV Size 150.00 GiB
Current LE 38399
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:3

--- Logical volume ---
LV Name /dev/pve/snap-vm
VG Name pve
LV UUID vl3mTC-cP31-acbp-xR1E-IXjU-EKuW-FSwOGN
LV Write Access read/write
LV Status available
# open 1
LV Size 200.00 GiB
Current LE 51200
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:7



df -h:

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/pve-root 9.7G 2.1G 7.1G 24% /
tmpfs 994M 0 994M 0% /lib/init/rw
udev 984M 248K 984M 1% /dev
tmpfs 994M 19M 975M 2% /dev/shm
/dev/sda1 958M 58M 851M 7% /boot
/dev/fuse 30M 16K 30M 1% /etc/pve
/dev/mapper/pve-data-crypt
148G 7.3G 133G 6% /var/lib/vz
/dev/mapper/pve-snap-crypt
197G 2.3G 185G 2% /snapshot-vm


So you see that I am using dm_crypt "after" the LVM so that /dev/mapper/pve-snap-crypt is my encrypted drive that is used later on.



In the webinterface I have set up a the directory

/snapshot-vm to be called vm-snapshots

and to be a storage for backups only.


INFO: starting new backup job: vzdump 101 --mode snapshot --compress lzo --storage vm-snapshots
INFO: Starting Backup of VM 101 (qemu)
INFO: status = running
INFO: mode failure - unable to detect lvm volume group
INFO: trying 'suspend' mode instead
INFO: backup mode: suspend
INFO: ionice priority: 7
INFO: suspend vm
INFO: creating archive '/snapshot-vm/dump/vzdump-qemu-101-2012_04_15-19_54_35.tar.lzo'
INFO: adding '/snapshot-vm/dump/vzdump-qemu-101-2012_04_15-19_54_35.tmp/qemu-server.conf' to archive ('qemu-server.conf')
INFO: adding '/var/lib/vz/images/101/vm-101-disk-2.raw' to archive ('vm-disk-virtio0.raw')
INFO: Total bytes written: 53687093760 (200.00 MiB/s)
INFO: archive file size: 522MB
INFO: resume vm
INFO: vm is online again after 258 seconds
INFO: Finished Backup of VM 101 (00:04:18)
INFO: Backup job finished successfully
TASK OK




Any more information needed to help me? And any hints that I could try? I already tried the "LC_ALL=C" and I also tried it on my test machine where everything worked out alright (no encryption on my test machine).

Thank you for helping me!

Jörg

PS:

cat /proc/mounts

none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
none /dev devtmpfs rw,relatime,size=1007112k,nr_inodes=251778,mode=755 0 0
none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
/dev/mapper/pve-root / ext3 rw,relatime,errors=remount-ro,barrier=0,data=ordered 0 0
tmpfs /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
/dev/sda1 /boot ext3 rw,relatime,errors=remount-ro,barrier=0,data=ordered 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
/dev/fuse /etc/pve fuse rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other 0 0
beancounter /proc/vz/beancounter cgroup rw,relatime,blkio,name=beancounter 0 0
container /proc/vz/container cgroup rw,relatime,freezer,devices,name=container 0 0
fairsched /proc/vz/fairsched cgroup rw,relatime,cpuacct,cpu,cpuset,name=fairsched 0 0
/dev/mapper/pve-data-crypt /var/lib/vz ext3 rw,relatime,errors=continue,barrier=0,data=ordered 0 0
/dev/mapper/pve-snap-crypt /snapshot-vm ext3 rw,relatime,errors=continue,barrier=0,data=ordered 0 0



pveversion --verbose

pve-manager: 2.0-59 (pve-manager/2.0/18400f07)
running kernel: 2.6.32-11-pve
proxmox-ve-2.6.32: 2.0-66
pve-kernel-2.6.32-11-pve: 2.6.32-66
lvm2: 2.02.88-2pve2
clvm: 2.02.88-2pve2
corosync-pve: 1.4.3-1
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.8-3
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.7-2
pve-cluster: 1.0-26
qemu-server: 2.0-38
pve-firmware: 1.0-15
libpve-common-perl: 1.0-26
libpve-access-control: 1.0-18
libpve-storage-perl: 2.0-17
vncterm: 1.0-2
vzctl: 3.0.30-2pve2
vzprocps: not correctly installed
vzquota: 3.0.12-3
pve-qemu-kvm: 1.0-9
ksm-control-daemon: 1.1-1
 
Last edited:
So I changed my setup the following way and it works perfect!

/dev/sdX1 --> Luks mapper /dev/mapper/encrypted --> /LVM /dev/mapper/pve-data

Therefore the LVM does not know that it is located on an encrypted volume and works exactly the same as with an ordinary hd partition.

Snapshots etc. work just fine and everything is now running for weeks.
 

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