Man/vzctl.8

NAME

vzctl − perform various operations on an OpenVZ container

SYNOPSIS

	vzctl		[flags] create CTID --parameter value [...]
	vzctl		[flags] start CTID [--wait] [--force] [--skip-fsck] [--skip-remount]
	vzctl		[flags] stop CTID [--fast] [--skip-umount]
	vzctl		[flags] restart CTID [--wait] [--force] [--fast] [--skip-fsck] [--skip-remount]
	vzctl		[flags] suspend | resume CTID [--dumpfile name]
	vzctl		[flags] snapshot CTID [--id uuid] [--name name] [--description desc] [--skip-suspend] [--skip-config]
	vzctl		[flags] snapshot-switch CTID [--skip-resume | --must-resume] [--skip-config] --id uuid
	vzctl		[flags] snapshot-delete CTID --id uuid
	vzctl		[flags] snapshot-mount CTID --id uuid --target dir
	vzctl		[flags] snapshot-umount CTID --id uuid
	vzctl		[flags] snapshot-list CTID [-H] [-o field[,field...] [--id uuid]
	vzctl		[flags] set CTID --parameter value [...] [--save] [--force] [--setmode restart|ignore]
	vzctl		[flags] set CTID --reset_ub
	vzctl		[flags] destroy | delete | mount | umount | status | quotaon | quotaoff | quotainit CTID
	vzctl		[flags] console CTID [ttynum]
	vzctl		[flags] convert CTID [--layout ploop[:{expanded|plain|raw}]]
	vzctl		[flags] compact CTID
	vzctl		[flags] exec | exec2 CTID command [arg ...]
	vzctl		[flags] enter CTID [--exec command [arg ...]]
	vzctl		[flags] runscript CTID script
	vzctl		--help | --version

DESCRIPTION

Utility vzctl runs on the host system (otherwise known as Hardware Node, or HN) and performs direct manipulations with containers (CTs).

Containers can be referred to by either numeric CTID or by name (see --name option). Note that CT ID <= 100 are reserved for OpenVZ internal purposes. A numeric ID should not be more than 2147483644.

OPTIONS

Flags

These flags come before a command, and can be used with any command. They affect logging to console (terminal) only, and do not affect logging to a log file.

--quiet

Disables output. Note that scripts run by vzctl are still able to produce some output.

--verbose

Increments logging level up from the default. Can be used multiple times. Default value is set to the value of VERBOSE parameter in the global configuration file vz.conf(5), or to 0 if not set by VERBOSE parameter.

Setting container parameters

	set		CTID [--onboot yes|no] [--bootorder number] [--root path] [--private path] [--mount_opts options] [--userpasswd user:pass] [--disabled yes|no] [--name name] [--description string] [--ostemplate string] [--stop-timeout seconds] [--ipadd addr] [--ipdel addr|all] [--hostname name] [--nameserver addr] [--searchdomain name] [--netif_add dev[,params...]] [--netif_del dev|all] [--ifname dev [--mac hwaddr] [--host_ifname dev] [--host_mac hwaddr] [--bridge name] [--mac_filter on|off]] [--numproc items] [--numtcpsock items] [--numothersock items] [--vmguarpages pages] [--kmemsize bytes] [--tcpsndbuf bytes] [--tcprcvbuf bytes] [--othersockbuf bytes] [--dgramrcvbuf bytes] [--oomguarpages pages] [--lockedpages pages] [--privvmpages pages] [--shmpages pages] [--numfile items] [--numflock items] [--numpty items] [--numsiginfo items] [--dcachesize bytes] [--numiptent num] [--physpages pages] [--swappages pages] [--ram bytes] [--swap bytes] [--vm_overcommit float] [--cpuunits num] [--cpulimit num] [--cpus num] [--cpumask cpus|auto|all] [--nodemask nodes|all] [--meminfo none|mode:value] [--iptables name[,...]] [--netfilter disabled|stateless|stateful|full] [--netdev_add ifname] [--netdev_del ifname] [--diskquota yes|no] [--diskspace num] [--diskinodes num] [--quotatime seconds] [--quotaugidlimit num] [--capability capname:on|off[,...]] [--devnodes param] [--devices param] [--pci_add dev] [--pci_del dev] [--features name:on|off[,...]] [--applyconfig name] [--applyconfig_map group] [--ioprio num] [--iolimit mbps] [--iopslimit iops] [--save] [--force] [--reset_ub] [--setmode restart|ignore]
			This command sets various container parameters. If the container is currently running, vzctl applies these parameters to the container. The following options can be used with set command.

Flags

--save

If this flag is given, parameters are saved in container configuration file ctid.conf(5).

--force

If this flag is given together with --save, parameters are saved even if the current kernel doesn’t support OpenVZ. Note this flag does not make sense without --save, so --save is required.

--reset_ub

If this flag is given, vzctl applies all User Beancounter parameters from the configuration file to a running container. This is helpful in case configuration file is modified manually. Please note this flag is exclusive, i.e. it can not be combined with any other options or flags.

--setmode restart | ignore

A few parameters can only be applied by restarting the container. By default, vzctl prints a warning if such parameters are supplied and a container is running. Use --setmode restart together with --save flag to restart a container in such a case, or --setmode ignore to suppress the warning.

Miscellaneous

--onboot yes | no

Sets whether the container will be started during system boot. The container will be started on boot by vz initscript if either this parameter is set to yes, or the container was running just before last reboot, and this parameter is not set to no. Default value is unset, meaning the container will be started if it was running before the last reboot.

--bootorder number

Sets the boot order priority for this CT. The higher the number is, the earlier in the boot process this container starts. By default this parameter is unset, which is considered to be the lowest priority, so containers with unset bootorder will start last.

--root path

Sets the path to root directory (VE_ROOT) for this container. This is essentially a mount point for container’s root directory. Argument can contain literal string $VEID, which will be substituted with the numeric CT ID.

--private path

Sets the path to private directory (VE_PRIVATE) for this container. This is a directory in which all the container’s files are stored. Argument can contain literal string $VEID, which will be substituted with the numeric CT ID.

--mount_opts option[,option...]

Sets additional mount options for container file system. Only applicable for ploop layout, ignored otherwise.

--userpasswd user:password

Sets password for the given user in a container, creating the user if it does not exists. Note that this option is not saved in configuration file at all (so --save flag is useless), it is applied directly to the container, by running distribution-specific programs inside the container. It is not recommended to combine this option with any other options.

In case container was not running, it is automatically started then all the appropriate changes are applied, then it is stopped.

Note that container should be created before using this option.

--disabled yes | no

Disable container start. To force the start of a disabled container, use vzctl start --force.

--name name

Add a name for a container. The name can later be used in subsequent calls to vzctl in place of CTID. Note this option can not be used without --save.

--description string

Add a textual description for a container.

--ostemplate string

Sets a new value of OSTEMPLATE parameter in container configuration file ctid.conf(5). Requires --save flag. Useful after a change/upgrade of a distribution running inside container, as vzctl uses the value of OSTEMPLATE to run distribution-specific scripts.

--stop-timeout seconds

Sets a time to wait for container to stop on vzctl stop before forcibly killing it, in seconds. Note this option can not be used without --save flag.

Special value of 0 means to use compiled-in default.

Networking

--ipadd addr

Adds an IP address addr to a given container. Address can optionally have a netmask specified in the CIDR notation (e.g. 10.1.2.3/25). Note that this option is incremental, so addr are added to already existing ones.

--ipdel addr | all

Removes IP address addr from a container. If you want to remove all the addresses, use --ipdel all.

--hostname name

Sets container hostname. vzctl writes it to the appropriate file inside a container (distribution-dependent).

--nameserver addr

Sets DNS server IP address for a container. If you want to set several nameservers, you should do it at once, so use --nameserver option multiple times in one call to vzctl, as all the name server values set in previous calls to vzctl are overwritten.

A special value of inherit can be used to auto-propagate nameserver value(s) from the host system’s /etc/resolv.conf file.

--searchdomain name

Sets DNS search domains for a container. If you want to set several search domains, you should do it at once, so use --searchdomain option multiple times in one call to vzctl, as all the search domain values set in previous calls to vzctl are overwritten.

A special value of inherit can be used to auto-propagate search domain value(s) from the host system’s /etc/resolv.conf file.

--netif_add ifname[,mac,host_ifname,host_mac,bridge]

Adds a virtual Ethernet device (veth) to a given container. Here ifname is the Ethernet device name in the container, mac is its MAC address, host_ifname is the Ethernet device name on the host, and host_mac is its MAC address. MAC addresses should be in the format like XX:XX:XX:XX:XX:XX. bridge is an optional parameter which can be used in custom network start scripts to automatically add the interface to a bridge. All parameters except ifname are optional and are automatically generated if not specified.

--netif_del dev_name | all

Removes virtual Ethernet device from a container. If you want to remove all devices, use all.

veth interface configuration

The following options can be used to reconfigure the already-created virtual Ethernet interface. To select the interface to configure, use --ifname name option.
--mac XX:XX:XX:XX:XX:XX

MAC address of interface inside a container.

--host_ifname name

interface name for virtual interface in the host system.

--host_mac XX:XX:XX:XX:XX:XX

MAC address of interface in the host system.

If you want an independent communication with the Container through the bridge, you should specify a multicast MAC address here (FE:FF:FF:FF:FF:FF).

--bridge name

Bridge name. Custom network start scripts can use this value to automatically add the interface to a bridge.

--mac_filter on | off

Enables/disables MAC address filtering for the Container veth device and the possibility of configuring the MAC address of this device from inside the Container. If the filtering is turned on:
• the veth device accepts only those packets that have a MAC address in their headers corresponding to that of this device (excluding all broadcast and multicast packets);
• it is impossible to modify the veth MAC address from inside the Container.

By default, this functionality is enabled for all veth devices existing inside the Container.

VSwap limits

The following options sets memory and swap limits for VSwap-enabled kernels (kernel version 042stab042 or greater).

Argument is in bytes, unless otherwise specified by an optional suffix. Available suffixes are:

• T, t - terabytes;
• G, g - gigabytes;
• M, m - megabytes;
• K, k - kilobytes;
• P, p - memory pages (arch-specific, usually 4KB);
• B, b - bytes (this is the default).
--ram bytes

Sets physical memory (RAM) available to a container. Actually, the option is a shortcut for setting --physpages limit (the barrier is set to 0).

--swap bytes

Set swap space available to a container. Actually, the option is a shortcut for setting --swappages limit (the barrier is set to 0).

--vm_overcommit float

Set VM overcommitment value to float. If set, it is used to calculate privmmpages parameter in case it is not set explicitly (see below). Default value is 0, meaning unlimited privvmpages.

vzctl checks if running kernel is VSwap capable, and refuses to use these parameters otherwise. This behavior can be overriden by using --force flag before parameters.

In VSwap mode, all beancounters other than RAM and swap become optional. Note though that if some optional beancounters are not set, they are calculated and set by vzctl implicitly, using the following formulae:

• lockedpages.barrier = oomguarpages.barrier = ram

• lockedpages.limit = oomguarpages.limit = unlimited

• vmguarpages.barrier = vmguarpages.limit = ram + swap

• privvmpages.barrier = privvmpages.limit = (ram + swap) * vm_overcommit

(if vm_overcommit is 0 or not set, privvmpages is set to "unlimited")

Here is an example of setting container 777 to have 512 megabytes of RAM and 1 gigabyte of swap:

   vzctl set 777 --ram 512M --swap 1G --save

User Beancounter limits

The following options sets barrier and limit for various user beancounters.

Note that for VSwap-enabled kernels (version 042stab042 or greater) these limits are optional, you must only set --ram and --swap (see above). For older kernels, these limits are obligatory.

Each option requires one or two arguments. In case of one argument, vzctl sets barrier and limit to the same value. In case of two colon-separated arguments, the first is a barrier, and the second is a limit. Each argument is either a number, a number with a suffix, or a special value unlimited.

Arguments are in items, pages or bytes. Note that page size is architecture-specific, it is 4096 bytes on x86 and x86_64 platforms.

You can also specify different suffixes for User Beancounter parameters (except for those which names start with num). For example, vzctl set CTID --privvmpages 5M:6M should set privvmpages’ barrier to 5 megabytes and its limit to 6 megabytes.

Available suffixes are:

• T, t - terabytes;
• G, g - gigabytes;
• M, m - megabytes;
• K, k - kilobytes;
• P, p - memory pages (arch-specific, usually 4KB);
• B, b - bytes.

You can also specify the literal word unlimited in place of a number. In that case the corresponding value will be set to LONG_MAX, i. e. the maximum possible value.
--numproc items[:items]

Maximum number of processes and kernel-level threads. Setting the barrier and the limit to different values does not make practical sense.

--numtcpsock items[:items]

Maximum number of TCP sockets. This parameter limits the number of TCP connections and, thus, the number of clients the server application can handle in parallel. Setting the barrier and the limit to different values does not make practical sense.

--numothersock items[:items]

Maximum number of non-TCP sockets (local sockets, UDP and other types of sockets). Setting the barrier and the limit to different values does not make practical sense.

--vmguarpages pages[:pages]

Memory allocation guarantee. This parameter controls how much memory is available to a container. The barrier is the amount of memory that container’s applications are guaranteed to be able to allocate. The meaning of the limit is currently unspecified; it should be set to unlimited.

--kmemsize bytes[:bytes]

Maximum amount of kernel memory used. This parameter is related to --numproc. Each process consumes certain amount of kernel memory - 16 KB at least, 30-50 KB typically. Very large processes may consume a bit more. It is important to have a certain safety gap between the barrier and the limit of this parameter: equal barrier and limit may lead to the situation where the kernel will need to kill container’s applications to keep the kmemsize usage under the limit.

--tcpsndbuf bytes[:bytes]

Maximum size of TCP send buffers. Barrier should be not less than 64 KB, and difference between barrier and limit should be equal to or more than value of numtcpsock multiplied by 2.5 KB.

--tcprcvbuf bytes[:bytes]

Maximum size of TCP receive buffers. Barrier should be not less than 64 KB, and difference between barrier and limit should be equal to or more than value of numtcpsock multiplied by 2.5 KB.

--othersockbuf bytes[:bytes]

Maximum size of other (non-TCP) socket send buffers. If container’s processes needs to send very large datagrams, the barrier should be set accordingly. Increased limit is necessary for high performance of communications through local (UNIX-domain) sockets.

--dgramrcvbuf bytes[:bytes]

Maximum size of other (non-TCP) socket receive buffers. If container’s processes needs to receive very large datagrams, the barrier should be set accordingly. The difference between the barrier and the limit is not needed.

--oomguarpages pages[:pages]

Guarantees against OOM kill. Under this beancounter the kernel accounts the total amount of memory and swap space used by the container’s processes. The barrier of this parameter is the out-of-memory guarantee. If the oomguarpages usage is below the barrier, processes of this container are guaranteed not to be killed in out-of-memory situations. The meaning of limit is currently unspecified; it should be set to unlimited.

--lockedpages pages[:pages]

Maximum number of pages acquired by mlock(2).

--privvmpages pages[:pages]

Allows controlling the amount of memory allocated by the applications. For shared (mapped as MAP_SHARED) pages, each container really using a memory page is charged for the fraction of the page (depending on the number of others using it). For "potentially private" pages (mapped as MAP_PRIVATE), container is charged either for a fraction of the size or for the full size if the allocated address space. In the latter case, the physical pages associated with the allocated address space may be in memory, in swap or not physically allocated yet.

The barrier and the limit of this parameter control the upper boundary of the total size of allocated memory. Note that this upper boundary does not guarantee that container will be able to allocate that much memory. The primary mechanism to control memory allocation is the --vmguarpages guarantee.

--shmpages pages[:pages]

Maximum IPC SHM segment size. Setting the barrier and the limit to different values does not make practical sense.

--numfile items[:items]

Maximum number of open files. In most cases the barrier and the limit should be set to the same value. Setting the barrier to 0 effectively disables pre-charging optimization for this beancounter in the kernel, which leads to the held value being precise but could slightly degrade file open performance.

--numflock items[:items]

Maximum number of file locks. Safety gap should be between barrier and limit.

--numpty items[:items]

Number of pseudo-terminals (PTY). Note that in OpenVZ each container can have not more than 255 PTYs. Setting the barrier and the limit to different values does not make practical sense.

--numsiginfo items[:items]

Number of siginfo structures. Setting the barrier and the limit to different values does not make practical sense.

--dcachesize bytes[:bytes]

Maximum size of filesystem-related caches, such as directory entry and inode caches. Exists as a separate parameter to impose a limit causing file operations to sense memory shortage and return an errno to applications, protecting from memory shortages during critical operations that should not fail. Safety gap should be between barrier and limit.

--numiptent num[:num]

Number of iptables (netfilter) entries. Setting the barrier and the limit to different values does not make practical sense.

--physpages pages[:pages]

On VSwap-enabled kernels, this limits the amount of physical memory (RAM) available to a container. The barrier should be set to 0, and the limit to a total size of RAM that can be used used by a container.

For older kernels, this is an accounting-only parameter, showing the usage of RAM by this container. Barrier should be set to 0, and limit should be set to unlimited.

--swappages pages[:pages]

For VSwap-enabled kernels (042stab042 or greater), this parameter limits the amount of swap space available to a container. The barrier should be set to 0, and the limit to a total size of swap that can be used by a container.

For older (pre-VSwap) kernels, the limit is used to show a total amount of swap space available inside the container. The barrier of this parameter is ignored. The default value is unlimited, meaning total swap will be reported as 0.

CPU fair scheduler parameters

These parameters control CPU usage by container.
--cpuunits num

CPU weight for a container. Argument is positive non-zero number, passed to and used in the kernel fair scheduler. The larger the number is, the more CPU time this container gets. Maximum value is 500000, minimal is 8. Number is relative to weights of all the other running containers. If cpuunits are not specified, default value of 1000 is used.

You can set CPU weight for CT0 (host system itself) as well (use vzctl set 0 --cpuunits num). Usually, OpenVZ initscript (/etc/init.d/vz) takes care of setting this.

--cpulimit num[%]

Limit of CPU usage for the container, in per cent. Note if the computer has 2 CPUs, it has total of 200% CPU time. Default CPU limit is 0 (no CPU limit).

--cpus num

sets number of CPUs available in the container.

--cpumask cpus | auto | all

Sets list of allowed CPUs for the container. Input format is a comma-separated list of decimal numbers and/or ranges. Consecutively set bits are shown as two hyphen-separated decimal numbers, the smallest and largest bit numbers set in the range. For example, if you want the container to execute on CPUs 0, 1, 2, 7, you should pass 0-2,7. Default value is all (the container can execute on any CPU). If used with the --nodemask option, value of auto assigns all CPUs from the specified NUMA node to a container.

--nodemask nodes | all

Sets list of allowed NUMA nodes for the container. Input format is the same as for --cpumask. Note that --nodemask must be used with the --cpumask option.

Memory output parameters

For VSwap-enabled kernels (042stab042 or greater), this parameter is ignored. For older kernels, it controls the output of /proc/meminfo inside a container.
--meminfo none

No /proc/meminfo virtualization (the same as on host system).

--meminfo mode:value

Configure total memory output in a container. Reported free memory is evaluated accordingly to the mode being set. Reported swap is evaluated according to the settings of --swappages parameter.

You can use the following modes for mode:
• pages:value - sets total memory in pages;
• privvmpages:value - sets total memory as privvmpages * value.

Default is privvmpages:1.

Netfilter (iptables) control parameters

--netfilter disabled|stateless|stateful|full

Restrict access to netfilter/iptables modules for a container. This option replaces obsoleted --iptables.

Note that changing this parameter requires container restart, so consider using --setmode option.

The following arguments can be used:
• disabled

no modules are allowed

• stateless

all modules except NAT and conntracks are allowed (i.e. filter and mangle); this is the default

• stateful

all modules except NAT are allowed

• full

all modules are allowed

--iptables name[,...]

Note this option is obsoleted, --netfilter should be used instead.

Allow to use the functionality of name iptables module inside the container. Multiple comma-separated names can be specified.

The default list of enabled iptables modules is defined by the IPTABLES variable in vz.conf(5).

You can use the following values for name: iptable_filter, iptable_mangle, ipt_limit, ipt_multiport, ipt_tos, ipt_TOS, ipt_REJECT, ipt_TCPMSS, ipt_tcpmss, ipt_ttl, ipt_LOG, ipt_length, ip_conntrack, ip_conntrack_ftp, ip_conntrack_irc, ipt_conntrack, ipt_state, ipt_helper, iptable_nat, ip_nat_ftp, ip_nat_irc, ipt_REDIRECT, xt_mac, ipt_recent, ipt_owner.

Network devices control parameters

--netdev_add name

move network device from the host system to a specified container

--netdev_del name

delete network device from a specified container

Disk quota parameters

--diskquota yes | no

allows to enable or disable disk quota for a container. By default, a global value (DISK_QUOTA) from vz.conf(5) is used.

Note that this parameter is ignored for ploop layout.

--diskspace num[:num]

For simfs layout, sets soft and hard disk quota limits. First parameter is soft limit, second is hard limit.

For ploop layout, initiates the procedure of resizing the ploop image file to the new size. Since there is no soft/hard limit concept in ploop, second num, if specified, is ignored.

By default, ploop resize is done online, i.e. on a mounted ploop. This is a preferred way of doing resize. Although, in a rare case a container was using lots of disk space and should now be resized to a much smaller size, an offline resize might be more appropriate. In this case, make sure the container is stopped and unmounted and use additional --offline-resize option

Note that ploop resize is NOT performed on container start, so for consistency --diskspace must be used together with --save flag.

Suffixes G, M, K can also be specified (see Resource limits section for more info on suffixes). If suffix is not specified, value is in kilobytes.

--diskinodes num[:num]

sets soft and hard disk quota limits, in i-nodes. First parameter is soft limit, second is hard limit.

Note that this parameter is ignored for ploop layout.

--quotatime seconds

sets quota grace period. Container is permitted to exceed its soft limits for the grace period, but once it has expired, the soft limit is enforced as a hard limit.

Note that this parameter is ignored for ploop layout.

--quotaugidlimit num

Enables or disables in-container per-user and per-group disk quotas. If the value is set to 0 or not set, disk quotas inside the container is disabled and not accounted.

For simfs layout containers, non-zero value sets maximum number of user/group IDs for which disk quota is accounted.

For ploop layout containers, any non-zero value enables disk quota inside the container; the number of user/group IDs used by disk quota is not limited by OpenVZ.

Note that enabling or disabling in-container disk quotas requires container restart, so consider using --setmode option.

Capability option

--capability capname:on|off[,...]

Sets a capability for a container. Multiple comma-separated capabilities can be specified.

Note that setting a capability when the container is running does not take immediate effect; restart the container in order for the changes to take effect (consider using --setmode option).

A container has the default set of capabilities, thus any operation on capabilities is "logical AND" with the default capability mask.

You can use the following values for capname: chown, dac_override, dac_read_search, fowner, fsetid, kill, setgid, setuid, setpcap, linux_immutable, net_bind_service, net_broadcast, net_admin, net_raw, ipc_lock, ipc_owner, sys_module, sys_rawio, sys_chroot, sys_ptrace, sys_pacct, sys_admin, sys_boot, sys_nice, sys_resource, sys_time, sys_tty_config, mknod, lease, setveid, ve_admin. For detailed description, see capabilities(7).

WARNING: setting some of those capabilities may have far reaching security implications, so do not do it unless you know what you are doing. Also note that setting setpcap:on for a container will most probably lead to inability to start it.

Device access management

--devnodes device:[r][w][q]|none

Give the container an access (r - read, w - write, q - disk quota management, none - no access) to a device designated by the special file /dev/device. Device file is created in a container by vzctl. Example:

   vzctl set 777 --devnodes sdb:rwq

--devices b|c:major:minor|all:[r][w][q]|none

Give the container an access to a block or character device designated by its major and minor numbers. Device file have to be created manually.

PCI device management

--pci_add [domain:]bus:slot.func

Give the container an access to a specified PCI device. All numbers are hexadecimal (as printed by lspci(8) in the first column).

--pci_del [domain:]bus:slot.func

Delete a PCI device from the container.

Note that vps-pci configuration script is executed by vzctl then configuring PCI devices. The script is usually located at /usr/libexec/vzctl/scripts/.

Features management

--features name:on|off[,...]

Enable or disable a specific container feature. Known features are: sysfs, nfs, sit, ipip, ppp, ipgre, bridge, nfsd. A few features can be specified at once, comma-separated.

Apply config

--applyconfig name

Read container parameters from the container sample configuration file /etc/vz/conf/ve-name.conf-sample, and apply them, if --save option specified save to the container config file. The following parameters are not changed: HOSTNAME, IP_ADDRESS, OSTEMPLATE, VE_ROOT, and VE_PRIVATE.

--applyconfig_map group

Apply container config parameters selected by group. Now the only possible value for group is name: to restore container name based on NAME variable in container configuration file.

I/O scheduling

--ioprio priority

Assigns disk I/O priority to container. Priority range is 0-7. The greater priority is, the more time for I/O activity container has. By default each container has priority of 4.

--iolimit limit[B|K|M|G]

Assigns disk I/O bandwidth limit for a container. Value is either a number with an optional suffix, or a literal string unlimited. Value of 0 means "unlimited". By default a container has no I/O limit. Maximum allowed limit is 2 gigabytes per second; values exceeding the limit are truncated.

If no suffix is provided, the limit is assumed to be in megabytes per second. Available suffixes are:
• b, B -- bytes per second;
• k, K -- kilobytes per second;
• m, M -- megabytes per second (default);
• g, G -- gigabytes per second;

--iopslimit iops

Assigns IOPS limit for a container, in number of input/output operations per second. Value is a number or a literal string unlimited. Value of 0 means "unlimited". By default a container has no IOPS limit.

Suspending and resuming

Checkpointing is a feature of OpenVZ kernel which allows to save a complete in-kernel state of a running container, and to restore it later.

suspend|chkpnt CTID [--dumpfile name]

This command suspends a container to a dump file If an option --dumpfile is not set, default dump file name /vz/dump/Dump.CTID is used.

resume|restore CTID [--dumpfile name]

This command restores a container from the dump file created by the suspend command.

Snapshotting

Snapshotting is a feature based on checkpointing and ploop shapshots. It allows to save a complete state of container file system. Plus, if the container is running, it’s in-memory state (as in checkpointing). Note that snapshot functionality is only working for containers on ploop device.

snapshot CTID [--id uuid] [--name name] [--description desc]
[--skip-suspend] [--skip-config]

Creates a container snapshot, i.e. saves the current container state, including its file system state, running processes state, and configuration file.

If a container is running, and --skip-suspend option is not specified, a container is checkpointed and then restored, and CT memory dump becomes the part of snapshot.

Unless --skip-config option is given, container configuration file is saved to the snapshot.

If uuid is not specified, it is auto-generated. Options --name and --description can be used to specify the snapshot name and description, respectively. Name is displayed by snapshot-list.

snapshot-switch CTID [--skip-resume | --must-resume] [--skip-config]
--id uuid

Switches the container to a snapshot identified by uuid, restoring its file system state, configuration (if available) and its running state (if available).

Note that the current state of a container (including its file system state and its configuration file) is lost!

Option --skip-resume is used to ignore a CT memory dump file in a snapshot, as a result the container will end up being in a stopped state (same as if a snapshot has been taken with --skip-suspend).

If option --must-resume is set, absense of a memory dump is treated as an error, and the inability to restore from the memory dump is treated as an error rather than warning.

Option option --skip-config is used to ignore the CT configuration file in a snapshot, i.e. the current configuration file will be left as is.

snapshot-delete CTID --id uuid

Removes a specified snapshot.

snapshot-mount CTID --id uuid --target directory

Mounts a snapshot specified by uuid to a directory. Note this mount is read-only.

snapshot-umount CTID --id uuid

Unmounts a specified snapshot.

snapshot-list CTID [-H] [-o field[,field...] [--id uuid]

List container’s snapshots.

You can suppress displaying header using -H option.

You can use the -o option to display only the specified field(s). List of available fields can be obtained using -L option.

Performing container actions

create

CTID [--ostemplate name] [--config name] [--layout simfs|ploop[:{expanded|plain|raw}]] [--diskspace kbytes] [--diskinodes num] [--private path] [--root path] [--ipadd addr] [--hostname name] [--name name] [--local_uid uid] [--local_gid gid]

Creates a new container area. This operation should be done once, before the first start of the container.

By default, an OS template denoted by DEF_OSTEMPLATE parameter of vz.conf(5) is used to create a container. This can be overwritten by --ostemplate option.

By default, a new container configuration file is created from a sample configuration denoted by value of CONFIGFILE parameter of vz.conf(5). If the container configuration file already exists, it will not be modified.

The value of CONFIGFILE can be overwritten by using the --config name option. This option can not be used if the container configuration file already exists.

A new container can either be created using simfs filesystem or on a ploop device. The default is set by value of VE_LAYOUT parameter of vz.conf(5) and can be overwritten by --layout option. In case ploop is used, one can additionally specify ploop disk image format after a colon. Possible ploop formats are expanded, plain and raw. Default is expanded. Using value other than expanded is not recommended and is currently not supported.

You can use --diskspace and --diskinodes options to specify container file system size. Note that for ploop layout, you will not be able to change inodes value later.

If DISKSPACE is not specified either in the sample configuration file used for creation or in global configuration file vz.conf(5), --diskspace parameter is required for ploop layout.

Suffixes G, M, K can also be specified (see Resource limits section for more info on suffixes).

You can use --root path option to sets the path to the mount point for the container root directory (default is VE_ROOT specified in vz.conf(5) file). Argument can contain literal string $VEID, which will be substituted with the numeric CT ID.

You can use --private path option to set the path to directory in which all the files and directories specific to this very container are stored (default is VE_PRIVATE specified in vz.conf(5) file). Argument can contain literal string $VEID, which will be substituted with the numeric CT ID.

You can use --ipadd addr option to assign an IP address to a container. Note that this option can be used multiple times.

You can use --hostname name option to set a host name for a container.

When running with an upstream Linux Kernel that supports user namespaces (>= 3.8), the parameters --local_uid and --local_gid can be used to select which uid and gid respectively will be used as a base user in the host system. Note that user namespaces provide a 1:1 mapping between container users and host users. If these options are not specified, the values LOCAL_UID and LOCAL_GID from global configuration file vz.conf(5) are used. An explicit --local_uid value of 0 will disable user namespace support, and run the container as a privileged user. In this case, --local_gid is ignored.

Warning: use --local_uid and --local_gid with care, specially when migrating containers. In all situations, the container’s files in the filesystem needs to be correctly owned by the host-side users.

destroy | delete CTID

Removes a container private area by deleting all files, directories and the configuration file of this container.

start CTID [--wait] [--force] [--skip-fsck] [--skip-remount]

Mounts (if necessary) and starts a container. Unless --wait option is specified, vzctl will return immediately; otherwise an attempt to wait till the default runlevel is reached will be made by vzctl.

Specify --force if you want to start a container which is disabled (see --disabled).

Specify --skip-fsck to skip fsck for ploop-based container filesystem (this option is used by vz initscript).

By default, if a container to be started happens to be already mounted, it is unmounted and mounted again. This behavior can be turned off by using --skip-remount flag.

Note that this command can lead to execution of premount, mount and start action scripts (see ACTION SCRIPTS below).

stop CTID [--fast] [--skip-umount]

Stops a container and unmounts it (unless --skip-umount is given). Normally, halt(8) is executed inside a container; option --fast makes vzctl use reboot(2) syscall instead which is faster but can lead to unclean container shutdown.

Note that vzctl stop is not asyncronous, in other words vzctl waits for container’s init to exit (unless --fast is given), which can take up to a few minutes. Default wait timeout is 120 seconds; it can be changed globally, by setting STOP_TIMEOUT in vz.conf(5), or per container (STOP_TIMEOUT in ctid.conf(5), see --stop-timeout).

Note that this command can lead to execution of stop, umount and postumount action scripts (see ACTION SCRIPTS below).

restart CTID [--wait] [--force] [--fast] [--skip-fsck]

Restarts a container, i.e. stops it if it is running, and starts again. Accepts all the start and stop options.

Note that this command can lead to execution of some action scripts (see ACTION SCRIPTS below).

status CTID

Shows a container status. This is a line with five or six words, separated by spaces.

First word is literally CTID.

Second word is the numeric CT ID.

Third word is showing whether this container exists or not, it can be either exist or deleted.

Fourth word is showing the status of the container filesystem, it can be either mounted or unmounted.

Fifth word shows if the container is running, it can be either running or down.

Sixth word, if exists, is suspended. It appears if a dump file exists for a stopped container (see suspend).

This command can also be usable from scripts.

mount CTID

Mounts container private area. Note that this command can lead to execution of premount and mount action scripts (see ACTION SCRIPTS below).

umount CTID

Unmounts container private area. Note that this command can lead to execution of umount and postumount action scripts (see ACTION SCRIPTS below).

Note that stop does umount automatically.

convert CTID [--layout ploop[:{expanded|plain|raw}]]

Convert CT private area to reside on a ploop device (available in kernel version 042stab052.8 and greater). Conversion should be performed when a container is stopped, plus disk space quota should be set.

compact CTID

Compact container image. This only makes sense for ploop layout.

quotaon CTID

Turn disk quota on. Not that mount and start does that automatically.

quotaoff CTID

Turn disk quota off. Not that umount and stop does that automatically.

quotainit CTID

Initialize disk quota (i.e. run vzquota init) with the parameters taken from the CT configuration file ctid.conf(5).

exec CTID command

Executes command in a container. Environment variables are not set inside the container. Signal handlers may differ from default settings. If command is -, commands are read from stdin.

exec2 CTID command

The same as exec, but return code is that of command.

runscript CTID script

Run specified shell script in the container. Argument script is a file on the host system which contents is read by vzctl and executed in the context of the container. For a running container, the command jumps into the container and executes the script. For a stopped container, it enters the container, mounts container’s root filesystem, executes the script, and unmounts CT root. In the latter case, the container is not really started, no file systems other than root (such as /proc) are mounted, no startup scripts are executed etc. Thus the environment in which the script is running is far from normal and is only usable for very basic operations.

enter CTID [--exec command [arg ...]]

Enters into a container (giving a container’s root shell). This option is a back-door for host root only. The proper way to have CT root shell is to use ssh(1).

Option --exec is used to run command with arguments after entering into container. This is useful if command to be run requires a terminal (so vzctl exec can not be used) and for some reason you can not use ssh(1).

You need to log out manually from the shell to finish session (even if you specified --exec).

console CTID [ttynum]

Attach to a container console. Optional ttynum argument is tty number (such as 4 for tty4), default is 1 which is used for container’s /dev/console.

Note the consoles are persistent, meaning that:
• it can be attached to even if the container is not running;
• there is no automatic detachment upon the container stop;
• detaching from the console leaves anything running in this console as is.

The following escape sequences are recognized by vzctl console. Note that these sequences are only recognized at the beginning of a line.

• Esc then . to detach from the console.

• Esc then ! to kill anything running on the console (SAK). This is helpful when one expects a login prompt but there isn’t one.

Other options

--help

Prints help message with a brief list of possible options.

--version

Prints vzctl version.

ACTION SCRIPTS

vzctl has an ability to execute user-defined scripts when a specific vzctl command is run for a container. The following vzctl commands can trigger execution of action scripts: start, stop, restart, mount and umount.

Action scripts are located in the /etc/vz/conf/ directory. There are global and per-CT scripts. Global scripts have a literal prefix of vps. and are executed for all containers. Per-CT scripts have a CTID. numeric prefix and are executed for the given container only.

Please note scripts are executed in a host system (CT0) context, with the exception of .start and .stop scripts, which are executed in a container context.

The following action scripts are currently defined:
vps.premount, CTID.premount

Global and per-CT mount scripts which are executed for a container before it is mounted. Scripts are executed in the host system context, while a CT is not yet mounted or running. Global script, if exists, is executed first.

vps.mount, CTID.mount

Global and per-CT mount scripts which are executed for a container right after it is mounted. Otherwise they are the same as .premount scripts.

CTID.start

Right after vzctl has started a container, it executes this script in a container context.

CTID.stop

Right before vzctl has stopped a container, it executes this script in a container context.

vps.umount, CTID.umount

Global and per-CT umount scripts which are executed for a container before it is unmounted. Scripts are executed in the host system context, while a CT is mounted. Global script, if exists, is executed first.

vps.postumount, CTID.postumount

Global and per-CT umount scripts which are executed for a container right after it is unmounted. Otherwise they are the same as .umount scripts.

The environment passed to all the *mount scripts is the standard environment of the parent (i.e. vzctl) with two additional variables: $VEID and $VE_CONFFILE. The first one holds the ID of the container, and the second one holds the full path to the container configuration file. If the script needs to get other CT configuration parameters, such as $VE_ROOT, it needs to get those from global and per-CT configuration files.

Here is an example of a mount script, which makes host system’s /mnt/disk available to container(s). Script name can either be /etc/vz/conf/vps.mount or /etc/vz/conf/CTID.mount.

   # If one of these files does not exist then something
   # is really broken
   [ -f /etc/vz/vz.conf ] || exit 1
   [ -f $VE_CONFFILE ] || exit 1
   # Source both files. Note the order is important.
   . /etc/vz/vz.conf
   . $VE_CONFFILE
   SRC=/mnt/disk
   DST=/mnt/disk
   mount -n -t simfs $SRC ${VE_ROOT}${DST} -o $SRC

EXIT STATUS

Returns 0 upon success, or an appropriate error code in case of an error:

	1		Failed to set a UBC parameter
	2		Failed to set a fair scheduler parameter
	3		Generic system error
	5		The running kernel is not an OpenVZ kernel (or some OpenVZ modules are not loaded)
	6		Not enough system resources
	7		ENV_CREATE ioctl failed
	8		Command executed by vzctl exec returned non-zero exit code
	9		Container is locked by another vzctl invocation
	10		Global OpenVZ configuration file vz.conf(5) not found
	11		A vzctl helper script file not found
	12		Permission denied
	13		Capability setting failed
	14		Container configuration file ctid.conf(5) not found
	15		Timeout on vzctl exec
	16		Error during vzctl suspend
	17		Error during vzctl resume
	18		Error from setluid() syscall
	20		Invalid command line parameter
	21		Invalid value for command line parameter
	22		Container root directory (VE_ROOT) not set
	23		Container private directory (VE_PRIVATE) not set
	24		Container template directory (TEMPLATE) not set
	28		Not all required UBC parameters are set, unable to start container
	29		OS template is not specified, unable to create container
	31		Container not running
	32		Container already running
	33		Unable to stop container
	34		Unable to add IP address to container
	40		Container not mounted
	41		Container already mounted
	43		Container private area not found
	44		Container private area already exists
	46		Not enough disk space
	47		Bad/broken container (/sbin/init or /bin/sh not found)
	48		Unable to create a new container private area
	49		Unable to create a new container root area
	50		Unable to mount container
	51		Unable to unmount container
	52		Unable to delete a container
	53		Container private area not exist
	60		vzquota on failed
	61		vzquota init failed
	62		vzquota setlimit failed
	63		Parameter DISKSPACE not set
	64		Parameter DISKINODES not set
	65		Error setting in-container disk quotas
	66		vzquota off failed
	67		ugid quota not initialized
	71		Incorrect IP address format
	74		Error changing password
	78		IP address already in use
	79		Container action script returned an error
	82		Config file copying error
	86		Error setting devices (--devices or --devnodes)
	89		IP address not available
	91		OS template not found
	99		Ploop is not supported by either the running kernel or vzctl.
	100		Unable to find container IP address
	104		VE_NETDEV ioctl error
	105		Container start disabled
	106		Unable to set iptables on a running container
	107		Distribution-specific configuration file not found
	109		Unable to apply a config
	129		Unable to set meminfo parameter
	130		Error setting veth interface
	131		Error setting container name
	133		Waiting for container start failed
	139		Error saving container configuration file
	148		Error setting container IO parameters (ioprio)
	150		Ploop image file not found
	151		Error creating ploop image
	152		Error mounting ploop image
	153		Error unmounting ploop image
	154		Error resizing ploop image
	155		Error converting container to ploop layout
	156		Error creating ploop snapshot
	157		Error merging ploop snapshot
	158		Error deleting ploop snapshot
	159		Error switching ploop snapshot
	166		Error compacting ploop image
	167		Error listing ploop snapsots

EXAMPLES

To create and start "basic" container with ID of 1000 using centos-5 OS template and IP address of 192.168.10.200:

   vzctl create 1000 --ostemplate centos-5 --config basic
   vzctl set 1000 --ipadd 192.168.10.200 --save
   vzctl start 1000

To set number of processes barrier/limit to 80/100, and PTY barrier/limit to 16/20 PTYs:

   vzctl set 1000 --numproc 80:100 -t 16:20 --save

To execute command ls -la in this container:

   vzctl exec 1000 /bin/ls -la

To execute command pipe ls -l / | sort in this container:

   vzctl exec 1000 ’ls -l / | sort’

To enter this container and execute command apt-get install vim:

   vzctl enter 1000 --exec apt-get install vim

Note that in the above example you will need to log out from the container’s shell after apt-get finishes.

To enter this container, execute command apt-get install vim and logout after successful installation (or stay inside the container if installation process failed) use &&:

   vzctl enter 1000 --exec "apt-get install vim && logout"

To enter this container, execute command apt-get install vim and logout independently of exit code of installation process use ;:

   vzctl enter 1000 --exec "apt-get install vim ; logout"

Note that you need to quote the command if you use && or ;.

To stop this container:

   vzctl stop 1000

To permanently remove this container:

   vzctl destroy 1000

FILES

/etc/vz/vz.conf
/etc/vz/conf/<i>CTID</i>.conf
/etc/vz/conf/vps.{premount,mount,umount,postumount}
/etc/vz/conf/<i>CTID</i>.{premount,mount,start,stop,umount,postumount}
/proc/vz/veinfo
/proc/vz/vzquota
/proc/user_beancounters
/proc/bc/*
/proc/fairsched

SEE ALSO

vz.conf(5), ctid.conf(5), arpsend(8), vzcalc(8), vzcfgvalidate(8), vzcpucheck(8), vzifup-post(8), vzlist(8), vzmemcheck(8), vzmigrate(8), vzpid(8), vzquota(8), vzsplit(8), vzubc(8), UBC.

LICENSE

Copyright (C) 2000-2013, Parallels, Inc. Licensed under GNU GPL.