Containers are a lightweight alternative to fully virtualized machines (VMs). They use the kernel of the host system that they run on, instead of emulating a full operating system (OS). This means that containers can access resources on the host system directly.
The runtime costs for containers is low, usually negligible. However, there are some drawbacks that need be considered:
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Only Linux distributions can be run in Proxmox Containers. It is not possible to run other operating systems like, for example, FreeBSD or Microsoft Windows inside a container.
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For security reasons, access to host resources needs to be restricted. Therefore, containers run in their own separate namespaces. Additionally some syscalls (user space requests to the Linux kernel) are not allowed within containers.
{pve} uses Linux Containers (LXC) as its underlying
container technology. The “Proxmox Container Toolkit” (pct) simplifies the
usage and management of LXC, by providing an interface that abstracts
complex tasks.
Containers are tightly integrated with {pve}. This means that they are aware of the cluster setup, and they can use the same network and storage resources as virtual machines. You can also use the {pve} firewall, or manage containers using the HA framework.
Our primary goal is to offer an environment that provides the benefits of using a VM, but without the additional overhead. This means that Proxmox Containers can be categorized as “System Containers”, rather than “Application Containers”.
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Note
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If you want to run application containers, for example, Docker images, it is recommended that you run them inside a Proxmox QEMU VM. This will give you all the advantages of application containerization, while also providing the benefits that VMs offer, such as strong isolation from the host and the ability to live-migrate, which otherwise isn’t possible with containers. |
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Integrated into {pve} graphical web user interface (GUI)
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Easy to use command-line tool
pct -
Access via {pve} REST API
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lxcfs to provide containerized /proc file system
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Control groups (cgroups) for resource isolation and limitation
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AppArmor and seccomp to improve security
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Modern Linux kernels
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Image based deployment (templates)
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Uses {pve} storage library
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Container setup from host (network, DNS, storage, etc.)
List of officially supported distributions can be found below.
Templates for the following distributions are available through our repositories. You can use pveam tool or the Graphical User Interface to download them.
Alpine Linux is a security-oriented, lightweight Linux distribution based on musl libc and busybox.
For currently supported releases see:
Arch Linux, a lightweight and flexible Linux® distribution that tries to Keep It Simple.
Arch Linux is using a rolling-release model, see its wiki for more details:
The CentOS Linux distribution is a stable, predictable, manageable and reproducible platform derived from the sources of Red Hat Enterprise Linux (RHEL)
For currently supported releases see:
An Open Source, community owned and governed, forever-free enterprise Linux distribution, focused on long-term stability, providing a robust production-grade platform. AlmaLinux OS is 1:1 binary compatible with RHEL® and pre-Stream CentOS.
For currently supported releases see:
Rocky Linux is a community enterprise operating system designed to be 100% bug-for-bug compatible with America’s top enterprise Linux distribution now that its downstream partner has shifted direction.
For currently supported releases see:
Debian is a free operating system, developed and maintained by the Debian project. A free Linux distribution with thousands of applications to meet our users' needs.
For currently supported releases see:
Devuan GNU+Linux is a fork of Debian without systemd that allows users to reclaim control over their system by avoiding unnecessary entanglements and ensuring Init Freedom.
For currently supported releases see:
Fedora creates an innovative, free, and open source platform for hardware, clouds, and containers that enables software developers and community members to build tailored solutions for their users.
For currently supported releases see:
a highly flexible, source-based Linux distribution.
Gentoo is using a rolling-release model.
The makers' choice for sysadmins, developers and desktop users.
For currently supported releases see:
Ubuntu is the modern, open source operating system on Linux for the enterprise server, desktop, cloud, and IoT.
For currently supported releases see:
Container images, sometimes also referred to as “templates” or
“appliances”, are tar archives which contain everything to run a container.
{pve} itself provides a variety of basic templates for the
most common Linux distributions. They can be
downloaded using the GUI or the pveam (short for {pve} Appliance Manager)
command-line utility. Additionally, TurnKey
Linux container templates are also available to download.
The list of available templates is updated daily through the pve-daily-update timer. You can also trigger an update manually by executing:
# pveam update
To view the list of available images run:
# pveam available
You can restrict this large list by specifying the section you are
interested in, for example basic system images:
# pveam available --section system system alpine-3.12-default_20200823_amd64.tar.xz system alpine-3.13-default_20210419_amd64.tar.xz system alpine-3.14-default_20210623_amd64.tar.xz system archlinux-base_20210420-1_amd64.tar.gz system centos-7-default_20190926_amd64.tar.xz system centos-8-default_20201210_amd64.tar.xz system debian-9.0-standard_9.7-1_amd64.tar.gz system debian-10-standard_10.7-1_amd64.tar.gz system devuan-3.0-standard_3.0_amd64.tar.gz system fedora-33-default_20201115_amd64.tar.xz system fedora-34-default_20210427_amd64.tar.xz system gentoo-current-default_20200310_amd64.tar.xz system opensuse-15.2-default_20200824_amd64.tar.xz system ubuntu-16.04-standard_16.04.5-1_amd64.tar.gz system ubuntu-18.04-standard_18.04.1-1_amd64.tar.gz system ubuntu-20.04-standard_20.04-1_amd64.tar.gz system ubuntu-20.10-standard_20.10-1_amd64.tar.gz system ubuntu-21.04-standard_21.04-1_amd64.tar.gz
Before you can use such a template, you need to download them into one of your
storages. If you’re unsure to which one, you can simply use the local named
storage for that purpose. For clustered installations, it is preferred to use a
shared storage so that all nodes can access those images.
# pveam download local debian-10.0-standard_10.0-1_amd64.tar.gz
You are now ready to create containers using that image, and you can list all
downloaded images on storage local with:
# pveam list local local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz 219.95MB
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Tip
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You can also use the {pve} web interface GUI to download, list and delete container templates. |
pct uses them to create a new container, for example:
# pct create 999 local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
The above command shows you the full {pve} volume identifiers. They include the storage name, and most other {pve} commands can use them. For example you can delete that image later with:
# pveam remove local:vztmpl/debian-10.0-standard_10.0-1_amd64.tar.gz
General settings of a container include
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the Node : the physical server on which the container will run
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the CT ID: a unique number in this {pve} installation used to identify your container
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Hostname: the hostname of the container
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Resource Pool: a logical group of containers and VMs
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Password: the root password of the container
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SSH Public Key: a public key for connecting to the root account over SSH
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Unprivileged container: this option allows to choose at creation time if you want to create a privileged or unprivileged container.
Unprivileged containers use a new kernel feature called user namespaces. The root UID 0 inside the container is mapped to an unprivileged user outside the container. This means that most security issues (container escape, resource abuse, etc.) in these containers will affect a random unprivileged user, and would be a generic kernel security bug rather than an LXC issue. The LXC team thinks unprivileged containers are safe by design.
This is the default option when creating a new container.
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Note
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If the container uses systemd as an init system, please be aware the systemd version running inside the container should be equal to or greater than 220. |
Security in containers is achieved by using mandatory access control AppArmor restrictions, seccomp filters and Linux kernel namespaces. The LXC team considers this kind of container as unsafe, and they will not consider new container escape exploits to be security issues worthy of a CVE and quick fix. That’s why privileged containers should only be used in trusted environments.
You can restrict the number of visible CPUs inside the container using the
cores option. This is implemented using the Linux cpuset cgroup
(control group).
A special task inside pvestatd tries to distribute running containers among
available CPUs periodically.
To view the assigned CPUs run the following command:
# pct cpusets --------------------- 102: 6 7 105: 2 3 4 5 108: 0 1 ---------------------
Containers use the host kernel directly. All tasks inside a container are handled by the host CPU scheduler. {pve} uses the Linux CFS (Completely Fair Scheduler) scheduler by default, which has additional bandwidth control options.
cpulimit:
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You can use this option to further limit assigned CPU time. Please note that this is a floating point number, so it is perfectly valid to assign two cores to a container, but restrict overall CPU consumption to half a core. cores: 2 cpulimit: 0.5 |
cpuunits:
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This is a relative weight passed to the kernel scheduler. The
larger the number is, the more CPU time this container gets. Number is relative
to the weights of all the other running containers. The default is |
Container memory is controlled using the cgroup memory controller.
memory:
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Limit overall memory usage. This corresponds to the
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swap:
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Allows the container to use additional swap memory from the host
swap space. This corresponds to the |
The root mount point is configured with the rootfs property. You can
configure up to 256 additional mount points. The corresponding options are
called mp0 to mp255. They can contain the following settings:
Currently there are three types of mount points: storage backed mount points, bind mounts, and device mounts.
rootfs configurationrootfs: thin1:base-100-disk-1,size=8G
Storage backed mount points are managed by the {pve} storage subsystem and come in three different flavors:
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Image based: these are raw images containing a single ext4 formatted file system.
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ZFS subvolumes: these are technically bind mounts, but with managed storage, and thus allow resizing and snapshotting.
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Directories: passing
size=0triggers a special case where instead of a raw image a directory is created.
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Note
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The special option syntax STORAGE_ID:SIZE_IN_GB for storage backed
mount point volumes will automatically allocate a volume of the specified size
on the specified storage. For example, calling
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pct set 100 -mp0 thin1:10,mp=/path/in/container
will allocate a 10GB volume on the storage thin1 and replace the volume ID
place holder 10 with the allocated volume ID, and setup the moutpoint in the
container at /path/in/container
Bind mounts allow you to access arbitrary directories from your Proxmox VE host inside a container. Some potential use cases are:
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Accessing your home directory in the guest
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Accessing an USB device directory in the guest
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Accessing an NFS mount from the host in the guest
Bind mounts are considered to not be managed by the storage subsystem, so you cannot make snapshots or deal with quotas from inside the container. With unprivileged containers you might run into permission problems caused by the user mapping and cannot use ACLs.
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Note
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The contents of bind mount points are not backed up when using vzdump.
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Warning
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For security reasons, bind mounts should only be established using
source directories especially reserved for this purpose, e.g., a directory
hierarchy under /mnt/bindmounts. Never bind mount system directories like
/, /var or /etc into a container - this poses a great security risk.
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Note
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The bind mount source path must not contain any symlinks. |
For example, to make the directory /mnt/bindmounts/shared accessible in the
container with ID 100 under the path /shared, add a configuration line such as:
mp0: /mnt/bindmounts/shared,mp=/shared
into /etc/pve/lxc/100.conf.
Or alternatively use the pct tool:
pct set 100 -mp0 /mnt/bindmounts/shared,mp=/shared
to achieve the same result.
Device mount points allow to mount block devices of the host directly into the
container. Similar to bind mounts, device mounts are not managed by {PVE}'s
storage subsystem, but the quota and acl options will be honored.
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Note
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Device mount points should only be used under special circumstances. In most cases a storage backed mount point offers the same performance and a lot more features. |
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Note
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The contents of device mount points are not backed up when using
vzdump.
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You can configure up to 10 network interfaces for a single container.
The corresponding options are called net0 to net9, and they can contain the
following setting:
To automatically start a container when the host system boots, select the option Start at boot in the Options panel of the container in the web interface or run the following command:
# pct set CTID -onboot 1
If you want to fine tune the boot order of your containers, you can use the following parameters:
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Start/Shutdown order: Defines the start order priority. For example, set it to 1 if you want the CT to be the first to be started. (We use the reverse startup order for shutdown, so a container with a start order of 1 would be the last to be shut down)
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Startup delay: Defines the interval between this container start and subsequent containers starts. For example, set it to 240 if you want to wait 240 seconds before starting other containers.
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Shutdown timeout: Defines the duration in seconds {pve} should wait for the container to be offline after issuing a shutdown command. By default this value is set to 60, which means that {pve} will issue a shutdown request, wait 60s for the machine to be offline, and if after 60s the machine is still online will notify that the shutdown action failed.
Please note that containers without a Start/Shutdown order parameter will always start after those where the parameter is set, and this parameter only makes sense between the machines running locally on a host, and not cluster-wide.
If you require a delay between the host boot and the booting of the first container, see the section on Proxmox VE Node Management.
You can add a hook script to CTs with the config property hookscript.
# pct set 100 -hookscript local:snippets/hookscript.pl
It will be called during various phases of the guests lifetime. For an example
and documentation see the example script under
/usr/share/pve-docs/examples/guest-example-hookscript.pl.
Containers use the kernel of the host system. This exposes an attack surface for malicious users. In general, full virtual machines provide better isolation. This should be considered if containers are provided to unknown or untrusted people.
To reduce the attack surface, LXC uses many security features like AppArmor, CGroups and kernel namespaces.
AppArmor profiles are used to restrict access to possibly dangerous actions.
Some system calls, i.e. mount, are prohibited from execution.
To trace AppArmor activity, use:
# dmesg | grep apparmor
Although it is not recommended, AppArmor can be disabled for a container. This brings security risks with it. Some syscalls can lead to privilege escalation when executed within a container if the system is misconfigured or if a LXC or Linux Kernel vulnerability exists.
To disable AppArmor for a container, add the following line to the container
configuration file located at /etc/pve/lxc/CTID.conf:
lxc.apparmor.profile = unconfined
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Warning
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Please note that this is not recommended for production use. |
cgroup is a kernel mechanism used to hierarchically organize processes and distribute system resources.
The main resources controlled via cgroups are CPU time, memory and swap limits, and access to device nodes. cgroups are also used to "freeze" a container before taking snapshots.
Since {pve} 7.0, the default is a pure cgroupv2 environment. Previously a "hybrid" setup was used, where resource control was mainly done in cgroupv1 with an additional cgroupv2 controller which could take over some subsystems via the cgroup_no_v1 kernel command-line parameter. (See the kernel parameter documentation for details.)
The main difference between pure cgroupv2 and the old hybrid environments regarding {pve} is that with cgroupv2 memory and swap are now controlled independently. The memory and swap settings for containers can map directly to these values, whereas previously only the memory limit and the limit of the sum of memory and swap could be limited.
Another important difference is that the devices controller is configured in a completely different way. Because of this, file system quotas are currently not supported in a pure cgroupv2 environment.
cgroupv2 support by the container’s OS is needed to run in a pure cgroupv2 environment. Containers running systemd version 231 or newer support cgroupv2 [1], as do containers not using systemd as init system [2].
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Note
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CentOS 7 and Ubuntu 16.10 are two prominent Linux distributions releases, which have a systemd version that is too old to run in a cgroupv2 environment, you can either
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Tip
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If file system quotas are not required and all containers support cgroupv2, it is recommended to stick to the new default. |
To switch back to the previous version the following kernel command-line parameter can be used:
systemd.unified_cgroup_hierarchy=0
See this section on editing the kernel boot command line on where to add the parameter.
{pve} tries to detect the Linux distribution in the container, and modifies some files. Here is a short list of things done at container startup:
- set /etc/hostname
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to set the container name
- modify /etc/hosts
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to allow lookup of the local hostname
- network setup
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pass the complete network setup to the container
- configure DNS
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pass information about DNS servers
- adapt the init system
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for example, fix the number of spawned getty processes
- set the root password
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when creating a new container
- rewrite ssh_host_keys
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so that each container has unique keys
- randomize crontab
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so that cron does not start at the same time on all containers
Changes made by {PVE} are enclosed by comment markers:
# --- BEGIN PVE --- <data> # --- END PVE ---
Those markers will be inserted at a reasonable location in the file. If such a section already exists, it will be updated in place and will not be moved.
Modification of a file can be prevented by adding a .pve-ignore. file for it.
For instance, if the file /etc/.pve-ignore.hosts exists then the /etc/hosts
file will not be touched. This can be a simple empty file created via:
# touch /etc/.pve-ignore.hosts
Most modifications are OS dependent, so they differ between different
distributions and versions. You can completely disable modifications by
manually setting the ostype to unmanaged.
OS type detection is done by testing for certain files inside the
container. {pve} first checks the /etc/os-release file
[3].
If that file is not present, or it does not contain a clearly recognizable
distribution identifier the following distribution specific release files are
checked.
- Ubuntu
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inspect /etc/lsb-release (
DISTRIB_ID=Ubuntu) - Debian
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test /etc/debian_version
- Fedora
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test /etc/fedora-release
- RedHat or CentOS
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test /etc/redhat-release
- ArchLinux
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test /etc/arch-release
- Alpine
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test /etc/alpine-release
- Gentoo
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test /etc/gentoo-release
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Note
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Container start fails if the configured ostype differs from the auto
detected type.
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The {pve} LXC container storage model is more flexible than traditional container storage models. A container can have multiple mount points. This makes it possible to use the best suited storage for each application.
For example the root file system of the container can be on slow and cheap storage while the database can be on fast and distributed storage via a second mount point. See section Mount Points for further details.
Any storage type supported by the {pve} storage library can be used. This means
that containers can be stored on local (for example lvm, zfs or directory),
shared external (like iSCSI, NFS) or even distributed storage systems like
Ceph. Advanced storage features like snapshots or clones can be used if the
underlying storage supports them. The vzdump backup tool can use snapshots to
provide consistent container backups.
Furthermore, local devices or local directories can be mounted directly using bind mounts. This gives access to local resources inside a container with practically zero overhead. Bind mounts can be used as an easy way to share data between containers.
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Warning
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Because of existing issues in the Linux kernel’s freezer subsystem the usage of FUSE mounts inside a container is strongly advised against, as containers need to be frozen for suspend or snapshot mode backups. |
If FUSE mounts cannot be replaced by other mounting mechanisms or storage technologies, it is possible to establish the FUSE mount on the Proxmox host and use a bind mount point to make it accessible inside the container.
Quotas allow to set limits inside a container for the amount of disk space that each user can use.
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Note
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This currently requires the use of legacy cgroups. |
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Note
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This only works on ext4 image based storage types and currently only works with privileged containers. |
Activating the quota option causes the following mount options to be used for
a mount point:
usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0
This allows quotas to be used like on any other system. You can initialize the
/aquota.user and /aquota.group files by running:
# quotacheck -cmug / # quotaon /
Then edit the quotas using the edquota command. Refer to the documentation of
the distribution running inside the container for details.
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Note
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You need to run the above commands for every mount point by passing the
mount point’s path instead of just /.
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The standard Posix Access Control Lists are also available inside containers. ACLs allow you to set more detailed file ownership than the traditional user/group/others model.
To include a mount point in backups, enable the backup option for it in the
container configuration. For an existing mount point mp0
mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G
add backup=1 to enable it.
mp0: guests:subvol-100-disk-1,mp=/root/files,size=8G,backup=1
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Note
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When creating a new mount point in the GUI, this option is enabled by default. |
To disable backups for a mount point, add backup=0 in the way described
above, or uncheck the Backup checkbox on the GUI.
By default, additional mount points are replicated when the Root Disk is
replicated. If you want the {pve} storage replication mechanism to skip a mount
point, you can set the Skip replication option for that mount point.
As of {pve} 5.0, replication requires a storage of type zfspool. Adding a
mount point to a different type of storage when the container has replication
configured requires to have Skip replication enabled for that mount point.
It is possible to use the vzdump tool for container backup. Please refer to
the vzdump manual page for details.
Restoring container backups made with vzdump is possible using the pct
restore command. By default, pct restore will attempt to restore as much of
the backed up container configuration as possible. It is possible to override
the backed up configuration by manually setting container options on the
command line (see the pct manual page for details).
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Note
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pvesm extractconfig can be used to view the backed up configuration
contained in a vzdump archive.
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There are two basic restore modes, only differing by their handling of mount points:
If neither the rootfs parameter nor any of the optional mpX parameters are
explicitly set, the mount point configuration from the backed up configuration
file is restored using the following steps:
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Extract mount points and their options from backup
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Create volumes for storage backed mount points on the storage provided with the
storageparameter (default:local). -
Extract files from backup archive
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Add bind and device mount points to restored configuration (limited to root user)
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Note
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Since bind and device mount points are never backed up, no files are restored in the last step, but only the configuration options. The assumption is that such mount points are either backed up with another mechanism (e.g., NFS space that is bind mounted into many containers), or not intended to be backed up at all. |
This simple mode is also used by the container restore operations in the web interface.
By setting the rootfs parameter (and optionally, any combination of mpX
parameters), the pct restore command is automatically switched into an
advanced mode. This advanced mode completely ignores the rootfs and mpX
configuration options contained in the backup archive, and instead only uses
the options explicitly provided as parameters.
This mode allows flexible configuration of mount point settings at restore time, for example:
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Set target storages, volume sizes and other options for each mount point individually
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Redistribute backed up files according to new mount point scheme
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Restore to device and/or bind mount points (limited to root user)
The “Proxmox Container Toolkit” (pct) is the command-line tool to manage
{pve} containers. It enables you to create or destroy containers, as well as
control the container execution (start, stop, reboot, migrate, etc.). It can be
used to set parameters in the config file of a container, for example the
network configuration or memory limits.
Create a container based on a Debian template (provided you have already downloaded the template via the web interface)
# pct create 100 /var/lib/vz/template/cache/debian-10.0-standard_10.0-1_amd64.tar.gz
Start container 100
# pct start 100
Start a login session via getty
# pct console 100
Enter the LXC namespace and run a shell as root user
# pct enter 100
Display the configuration
# pct config 100
Add a network interface called eth0, bridged to the host bridge vmbr0, set
the address and gateway, while it’s running
# pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
Reduce the memory of the container to 512MB
# pct set 100 -memory 512
Destroying a container always removes it from Access Control Lists and it always removes the firewall configuration of the container. You have to activate --purge, if you want to additionally remove the container from replication jobs, backup jobs and HA resource configurations.
# pct destroy 100 --purge
Move a mount point volume to a different storage.
# pct move-volume 100 mp0 other-storage
Reassign a volume to a different CT. This will remove the volume mp0 from
the source CT and attaches it as mp1 to the target CT. In the background
the volume is being renamed so that the name matches the new owner.
# pct move-volume 100 mp0 --target-vmid 200 --target-volume mp1
In case pct start is unable to start a specific container, it might be
helpful to collect debugging output by passing the --debug flag (replace CTID with
the container’s CTID):
# pct start CTID --debug
Alternatively, you can use the following lxc-start command, which will save
the debug log to the file specified by the -o output option:
# lxc-start -n CTID -F -l DEBUG -o /tmp/lxc-CTID.log
This command will attempt to start the container in foreground mode, to stop
the container run pct shutdown CTID or pct stop CTID in a second terminal.
The collected debug log is written to /tmp/lxc-CTID.log.
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Note
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If you have changed the container’s configuration since the last start
attempt with pct start, you need to run pct start at least once to also
update the configuration used by lxc-start.
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If you have a cluster, you can migrate your Containers with
# pct migrate <ctid> <target>
This works as long as your Container is offline. If it has local volumes or mount points defined, the migration will copy the content over the network to the target host if the same storage is defined there.
Running containers cannot live-migrated due to technical limitations. You can do a restart migration, which shuts down, moves and then starts a container again on the target node. As containers are very lightweight, this results normally only in a downtime of some hundreds of milliseconds.
A restart migration can be done through the web interface or by using the
--restart flag with the pct migrate command.
A restart migration will shut down the Container and kill it after the specified timeout (the default is 180 seconds). Then it will migrate the Container like an offline migration and when finished, it starts the Container on the target node.
The /etc/pve/lxc/<CTID>.conf file stores container configuration, where
<CTID> is the numeric ID of the given container. Like all other files stored
inside /etc/pve/, they get automatically replicated to all other cluster
nodes.
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Note
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CTIDs < 100 are reserved for internal purposes, and CTIDs need to be unique cluster wide. |
ostype: debian arch: amd64 hostname: www memory: 512 swap: 512 net0: bridge=vmbr0,hwaddr=66:64:66:64:64:36,ip=dhcp,name=eth0,type=veth rootfs: local:107/vm-107-disk-1.raw,size=7G
The configuration files are simple text files. You can edit them using a normal
text editor, for example, vi or nano.
This is sometimes useful to do small corrections, but keep in mind that you
need to restart the container to apply such changes.
For that reason, it is usually better to use the pct command to generate and
modify those files, or do the whole thing using the GUI.
Our toolkit is smart enough to instantaneously apply most changes to running
containers. This feature is called “hot plug”, and there is no need to restart
the container in that case.
In cases where a change cannot be hot-plugged, it will be registered as a pending change (shown in red color in the GUI). They will only be applied after rebooting the container.
The container configuration file uses a simple colon separated key/value format. Each line has the following format:
# this is a comment OPTION: value
Blank lines in those files are ignored, and lines starting with a # character
are treated as comments and are also ignored.
It is possible to add low-level, LXC style configuration directly, for example:
lxc.init_cmd: /sbin/my_own_init
or
lxc.init_cmd = /sbin/my_own_init
The settings are passed directly to the LXC low-level tools.
When you create a snapshot, pct stores the configuration at snapshot time
into a separate snapshot section within the same configuration file. For
example, after creating a snapshot called “testsnapshot”, your configuration
file will look like this:
memory: 512 swap: 512 parent: testsnaphot ... [testsnaphot] memory: 512 swap: 512 snaptime: 1457170803 ...
There are a few snapshot related properties like parent and snaptime. The
parent property is used to store the parent/child relationship between
snapshots. snaptime is the snapshot creation time stamp (Unix epoch).
Container migrations, snapshots and backups (vzdump) set a lock to prevent
incompatible concurrent actions on the affected container. Sometimes you need
to remove such a lock manually (e.g., after a power failure).
# pct unlock <CTID>
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Caution
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Only do this if you are sure the action which set the lock is no longer running. |