snapshot feature is not available

Medvenda

Member
Oct 5, 2016
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Hello,
When i access to lxc container i find that the "take snapshot" button is disabled . Acroos Proxmox API i find the task error :

()


Task viewer: CT 111 - Snapshot

OutputStatus

Stop
TASK ERROR: snapshot feature is not available

proxmox-ve: 4.4-78 (running kernel: 4.4.35-2-pve)
pve-manager: 4.4-5 (running version: 4.4-5/c43015a5)
pve-kernel-4.2.6-1-pve: 4.2.6-36
pve-kernel-4.4.35-2-pve: 4.4.35-78
pve-kernel-4.4.21-1-pve: 4.4.21-71
lvm2: 2.02.116-pve3
corosync-pve: 2.4.0-1
libqb0: 1.0-1
pve-cluster: 4.0-48
qemu-server: 4.0-102
pve-firmware: 1.1-10
libpve-common-perl: 4.0-85
libpve-access-control: 4.0-19
libpve-storage-perl: 4.0-71
pve-libspice-server1: 0.12.8-1
vncterm: 1.2-1
pve-docs: 4.4-1
pve-qemu-kvm: 2.7.1-1
pve-container: 1.0-90
pve-firewall: 2.0-33
pve-ha-manager: 1.0-38
ksm-control-daemon: 1.2-1
glusterfs-client: 3.5.2-2+deb8u2
lxc-pve: 2.0.6-5
lxcfs: 2.0.5-pve2
criu: 1.6.0-1
novnc-pve: 0.5-8
smartmontools: 6.5+svn4324-1~pve80
zfsutils: 0.6.5.8-pve13~bpo80


Any suggestion to solve this problem ?
 
I think this is because you have no Tin pool on your LVM.

see
https://pve.proxmox.com/wiki/Logical_Volume_Manager_(LVM)
i have this informations

root@pve:~# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
data pve -wi-ao---- 425.88g
root pve -wi-ao---- 96.00g
swap pve -wi-ao---- 62.00g
root@pve:~# vgs
VG #PV #LV #SN Attr VSize VFree
pve 1 3 0 wz--n- 599.87g 16.00g
root@pve:~# pvs
PV VG Fmt Attr PSize PFree
/dev/sda3 pve lvm2 a-- 599.87g 16.00g
what's the problem ?
PS: i have a local storage (directory) with path "/var/lib/vz" contains raw machines
 
Last edited:
I understand that not all disk formats support snapshot, I'm sure qcow2 does if it does but I think raw does not.
I hope it is useful, regards
 
I understand that not all disk formats support snapshot, I'm sure qcow2 does if it does but I think raw does not.
I hope it is useful, regards
I think not i have another proxmox server with raw format of lxc in lvm-thin storage and snapshot feature is available. This is not the problem. I dont understand why data is displayed with "lvs" command and on the wizard of add new lvm storage i can't find it
 
As I thought you have no Thin-pool.
You have to create a thin-pool on your LV.

There are 1000 of HowTo in the net, how to build a thinpool on top of a LV.
 
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I believe it make sense to bump this topic once more.
I've noticed that there is an inconsistency in treatment of LXC snapshots and backups. Proxmox "unfairly" discriminates against the containers which have bind mounts, doesn't allow snapshots for these VMs ("snapshot feature is not available" "ERROR: pct snapshot..."). Yet at the same time it is OK to backup these machines. Why?
 
A potential solution is to use
lxc.mount.entry=/path/in/host/mount_point mount_point_in_container none bind 0 0 (for details see
https://wiki.debian.org/LXC#External_mounts_inside_the_container).
The CT operates fine, yet the snapshot feature gets back to work!
The only drawback so far is that lxc.mount.entris are not visible in the GUI. I hope Proxmox team will consider addin it eventually. This would be a usable workaround.
 
Hi Roman Shein,

A snapshot is at PVE a guest state at the snapshot time.
So all images must be consistent at this snapshot.
A bind-mount has no snapshot functionality.
It is a design decision that it is this way.
The LXC parameter is used anyway for bind mounts but you bypass this logic.
And a workaround will not show in the GUI.
 
Hi Roman Shein,

A snapshot is at PVE a guest state at the snapshot time.
So all images must be consistent at this snapshot.
A bind-mount has no snapshot functionality.
It is a design decision that it is this way.
The LXC parameter is used anyway for bind mounts but you bypass this logic.
And a workaround will not show in the GUI.

1) Conceptually the virtualization is about broadening the choice, increasing the freedom, not narrowing it down.
2) There is a valid business case to justify the "inconsistency". The appliance snapshots are very handy for recovering from an update gone wrong. The partial (appliance only) snapshot will allow for very granular (because of low storage requirements), near instant roll back to a good configuration. Yet in this situation you would want to rollback the appliance only, not the user data!
 

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