gnt-node.rst 17.5 KB
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gnt-node(8) Ganeti | Version @GANETI_VERSION@
=============================================

Name
----

gnt-node - Node administration

Synopsis
--------

**gnt-node** {command} [arguments...]

DESCRIPTION
-----------

The **gnt-node** is used for managing the (physical) nodes in the
Ganeti system.

COMMANDS
--------

ADD
~~~

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| **add** [--readd] [-s *secondary\_ip*] [-g *nodegroup*]
| [--master-capable=``yes|no``] [--vm-capable=``yes|no``]
| [--node-parameters *ndparams*]
| {*nodename*}
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Adds the given node to the cluster.

This command is used to join a new node to the cluster. You will
have to provide the password for root of the node to be able to add
the node in the cluster. The command needs to be run on the Ganeti
master.

Note that the command is potentially destructive, as it will
forcibly join the specified host the cluster, not paying attention
to its current status (it could be already in a cluster, etc.)

The ``-s`` is used in dual-home clusters and specifies the new node's
IP in the secondary network. See the discussion in **gnt-cluster**(8)
for more information.

In case you're readding a node after hardware failure, you can use
the ``--readd`` parameter. In this case, you don't need to pass the
secondary IP again, it will reused from the cluster. Also, the
drained and offline flags of the node will be cleared before
re-adding it.

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The ``--force-join`` option is to proceed with adding a node even if it already
appears to belong to another cluster. This is used during cluster merging, for
example.

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The ``-g`` is used to add the new node into a specific node group,
specified by UUID or name. If only one node group exists you can
skip this option, otherwise it's mandatory.

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The ``vm_capable``, ``master_capable`` and ``ndparams`` options are
described in **ganeti**(7), and are used to set the properties of the
new node.
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Example::

    # gnt-node add node5.example.com
    # gnt-node add -s 192.0.2.5 node5.example.com
    # gnt-node add -g group2 -s 192.0.2.9 node9.group2.example.com


ADD-TAGS
~~~~~~~~

**add-tags** [--from *file*] {*nodename*} {*tag*...}

Add tags to the given node. If any of the tags contains invalid
characters, the entire operation will abort.

If the ``--from`` option is given, the list of tags will be
extended with the contents of that file (each line becomes a tag).
In this case, there is not need to pass tags on the command line
(if you do, both sources will be used). A file name of - will be
interpreted as stdin.

EVACUATE
~~~~~~~~

**evacuate** [-f] [--early-release] [--iallocator *NAME* \|
--new-secondary *destination\_node*] {*node*...}

This command will move all secondary instances away from the given
node(s). It works only for instances having a drbd disk template.

The new location for the instances can be specified in two ways:

- as a single node for all instances, via the ``--new-secondary``
  option

- or via the ``--iallocator`` option, giving a script name as
  parameter, so each instance will be in turn placed on the (per the
  script) optimal node


The ``--early-release`` changes the code so that the old storage on
node being evacuated is removed early (before the resync is
completed) and the internal Ganeti locks are also released for both
the current secondary and the new secondary, thus allowing more
parallelism in the cluster operation. This should be used only when
recovering from a disk failure on the current secondary (thus the
old storage is already broken) or when the storage on the primary
node is known to be fine (thus we won't need the old storage for
potential recovery).

Example::

    # gnt-node evacuate -I dumb node3.example.com


FAILOVER
~~~~~~~~

**failover** [-f] [--ignore-consistency] {*node*}

This command will fail over all instances having the given node as
primary to their secondary nodes. This works only for instances having
a drbd disk template.

Normally the failover will check the consistency of the disks before
failing over the instance. If you are trying to migrate instances off
a dead node, this will fail. Use the ``--ignore-consistency`` option
for this purpose.

Example::

    # gnt-node failover node1.example.com


INFO
~~~~

**info** [*node*...]

Show detailed information about the nodes in the cluster. If you
don't give any arguments, all nodes will be shows, otherwise the
output will be restricted to the given names.

LIST
~~~~

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| **list**
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| [--no-headers] [--separator=*SEPARATOR*]
| [--units=*UNITS*] [-o *[+]FIELD,...*]
| [node...]

Lists the nodes in the cluster.

The ``--no-headers`` option will skip the initial header line. The
``--separator`` option takes an argument which denotes what will be
used between the output fields. Both these options are to help
scripting.

The units used to display the numeric values in the output varies,
depending on the options given. By default, the values will be
formatted in the most appropriate unit. If the ``--separator``
option is given, then the values are shown in mebibytes to allow
parsing by scripts. In both cases, the ``--units`` option can be
used to enforce a given output unit.

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Queries of nodes will be done in parallel with any running jobs. This might
give inconsistent results for the free disk/memory.
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The ``-o`` option takes a comma-separated list of output fields.
The available fields and their meaning are:



name
    the node name

pinst_cnt
    the number of instances having this node as primary

pinst_list
    the list of instances having this node as primary, comma separated

sinst_cnt
    the number of instances having this node as a secondary node

sinst_list
    the list of instances having this node as a secondary node, comma
    separated

pip
    the primary ip of this node (used for cluster communication)

sip
    the secondary ip of this node (used for data replication in dual-ip
    clusters, see gnt-cluster(8)

dtotal
    total disk space in the volume group used for instance disk
    allocations

dfree
    available disk space in the volume group

mtotal
    total memory on the physical node

mnode
    the memory used by the node itself

mfree
    memory available for instance allocations

bootid
    the node bootid value; this is a linux specific feature that
    assigns a new UUID to the node at each boot and can be use to
    detect node reboots (by tracking changes in this value)

tags
    comma-separated list of the node's tags

serial_no
    the so called 'serial number' of the node; this is a numeric field
    that is incremented each time the node is modified, and it can be
    used to detect modifications

ctime
    the creation time of the node; note that this field contains spaces
    and as such it's harder to parse

    if this attribute is not present (e.g. when upgrading from older
    versions), then "N/A" will be shown instead

mtime
    the last modification time of the node; note that this field
    contains spaces and as such it's harder to parse

    if this attribute is not present (e.g. when upgrading from older
    versions), then "N/A" will be shown instead

uuid
    Show the UUID of the node (generated automatically by Ganeti)

ctotal
    the toal number of logical processors

cnodes
    the number of NUMA domains on the node, if the hypervisor can
    export this information

csockets
    the number of physical CPU sockets, if the hypervisor can export
    this information

master_candidate
    whether the node is a master candidate or not

drained
    whether the node is drained or not; the cluster still communicates
    with drained nodes but excludes them from allocation operations

offline
    whether the node is offline or not; if offline, the cluster does
    not communicate with offline nodes; useful for nodes that are not
    reachable in order to avoid delays

role
    A condensed version of the node flags; this field will output a
    one-character field, with the following possible values:

    - *M* for the master node

    - *C* for a master candidate

    - *R* for a regular node

    - *D* for a drained node

    - *O* for an offline node

master_capable
    whether the node can become a master candidate

vm_capable
    whether the node can host instances

group
    the name of the node's group, if known (the query is done without
    locking, so data consistency is not guaranteed)

group.uuid
    the UUID of the node's group


If the value of the option starts with the character ``+``, the new
fields will be added to the default list. This allows to quickly
see the default list plus a few other fields, instead of retyping
the entire list of fields.

Note that some of this fields are known from the configuration of
the cluster (e.g. name, pinst, sinst, pip, sip and thus the master
does not need to contact the node for this data (making the listing
fast if only fields from this set are selected), whereas the other
fields are "live" fields and we need to make a query to the cluster
nodes.

Depending on the virtualization type and implementation details,
the mtotal, mnode and mfree may have slighly varying meanings. For
example, some solutions share the node memory with the pool of
memory used for instances (KVM), whereas others have separate
memory for the node and for the instances (Xen).

If no node names are given, then all nodes are queried. Otherwise,
only the given nodes will be listed.

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LIST-FIELDS
~~~~~~~~~~~

**list-fields** [field...]

Lists available fields for nodes.


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LIST-TAGS
~~~~~~~~~

**list-tags** {*nodename*}

List the tags of the given node.

MIGRATE
~~~~~~~

**migrate** [-f] [--non-live] [--migration-mode=live\|non-live]
{*node*}

This command will migrate all instances having the given node as
primary to their secondary nodes. This works only for instances
having a drbd disk template.

As for the **gnt-instance migrate** command, the options
``--no-live`` and ``--migration-mode`` can be given to influence
the migration type.

Example::

    # gnt-node migrate node1.example.com


MODIFY
~~~~~~

| **modify** [-f] [--submit]
| [--master-candidate=``yes|no``] [--drained=``yes|no``] [--offline=``yes|no``]
| [--master-capable=``yes|no``] [--vm-capable=``yes|no``] [--auto-promote]
| [-s *secondary_ip*]
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| [--node-parameters *ndparams*]
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| [--node-powered=``yes|no``]
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| {*node*}

This command changes the role of the node. Each options takes
either a literal yes or no, and only one option should be given as
yes. The meaning of the roles and flags are described in the
manpage **ganeti**(7).

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``--node-powered`` can be used to modify state-of-record if it doesn't reflect
the reality anymore.

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In case a node is demoted from the master candidate role, the
operation will be refused unless you pass the ``--auto-promote``
option. This option will cause the operation to lock all cluster nodes
(thus it will not be able to run in parallel with most other jobs),
but it allows automated maintenance of the cluster candidate pool. If
locking all cluster node is too expensive, another option is to
promote manually another node to master candidate before demoting the
current one.

Example (setting a node offline, which will demote it from master
candidate role if is in that role)::

    # gnt-node modify --offline=yes node1.example.com

The ``-s`` can be used to change the node's secondary ip. No drbd
instances can be running on the node, while this operation is
taking place.

Example (setting the node back to online and master candidate)::

    # gnt-node modify --offline=no --master-candidate=yes node1.example.com


REMOVE
~~~~~~

**remove** {*nodename*}

Removes a node from the cluster. Instances must be removed or
migrated to another cluster before.

Example::

    # gnt-node remove node5.example.com


REMOVE-TAGS
~~~~~~~~~~~

**remove-tags** [--from *file*] {*nodename*} {*tag*...}

Remove tags from the given node. If any of the tags are not
existing on the node, the entire operation will abort.

If the ``--from`` option is given, the list of tags to be removed will
be extended with the contents of that file (each line becomes a tag).
In this case, there is not need to pass tags on the command line (if
you do, tags from both sources will be removed). A file name of - will
be interpreted as stdin.

VOLUMES
~~~~~~~

| **volumes** [--no-headers] [--human-readable]
| [--separator=*SEPARATOR*] [--output=*FIELDS*]
| [*node*...]

Lists all logical volumes and their physical disks from the node(s)
provided.

The ``--no-headers`` option will skip the initial header line. The
``--separator`` option takes an argument which denotes what will be
used between the output fields. Both these options are to help
scripting.

The units used to display the numeric values in the output varies,
depending on the options given. By default, the values will be
formatted in the most appropriate unit. If the ``--separator``
option is given, then the values are shown in mebibytes to allow
parsing by scripts. In both cases, the ``--units`` option can be
used to enforce a given output unit.

The ``-o`` option takes a comma-separated list of output fields.
The available fields and their meaning are:

node
    the node name on which the volume exists

phys
    the physical drive (on which the LVM physical volume lives)

vg
    the volume group name

name
    the logical volume name

size
    the logical volume size

instance
    The name of the instance to which this volume belongs, or (in case
    it's an orphan volume) the character "-"


Example::

    # gnt-node volumes node5.example.com
    Node              PhysDev   VG    Name                                 Size Instance
    node1.example.com /dev/hdc1 xenvg instance1.example.com-sda_11000.meta 128  instance1.example.com
    node1.example.com /dev/hdc1 xenvg instance1.example.com-sda_11001.data 256  instance1.example.com


LIST-STORAGE
~~~~~~~~~~~~

| **list-storage** [--no-headers] [--human-readable]
| [--separator=*SEPARATOR*] [--storage-type=*STORAGE\_TYPE*]
| [--output=*FIELDS*]
| [*node*...]

Lists the available storage units and their details for the given
node(s).

The ``--no-headers`` option will skip the initial header line. The
``--separator`` option takes an argument which denotes what will be
used between the output fields. Both these options are to help
scripting.

The units used to display the numeric values in the output varies,
depending on the options given. By default, the values will be
formatted in the most appropriate unit. If the ``--separator``
option is given, then the values are shown in mebibytes to allow
parsing by scripts. In both cases, the ``--units`` option can be
used to enforce a given output unit.

The ``--storage-type`` option can be used to choose a storage unit
type. Possible choices are lvm-pv, lvm-vg or file.

The ``-o`` option takes a comma-separated list of output fields.
The available fields and their meaning are:

node
    the node name on which the volume exists

type
    the type of the storage unit (currently just what is passed in via
    ``--storage-type``)

name
    the path/identifier of the storage unit

size
    total size of the unit; for the file type see a note below

used
    used space in the unit; for the file type see a note below

free
    available disk space

allocatable
    whether we the unit is available for allocation (only lvm-pv can
    change this setting, the other types always report true)


Note that for the "file" type, the total disk space might not equal
to the sum of used and free, due to the method Ganeti uses to
compute each of them. The total and free values are computed as the
total and free space values for the filesystem to which the
directory belongs, but the used space is computed from the used
space under that directory *only*, which might not be necessarily
the root of the filesystem, and as such there could be files
outside the file storage directory using disk space and causing a
mismatch in the values.

Example::

    node1# gnt-node list-storage node2
    Node  Type   Name        Size Used   Free Allocatable
    node2 lvm-pv /dev/sda7 673.8G 1.5G 672.3G Y
    node2 lvm-pv /dev/sdb1 698.6G   0M 698.6G Y


MODIFY-STORAGE
~~~~~~~~~~~~~~

**modify-storage** [``--allocatable=yes|no``]
{*node*} {*storage-type*} {*volume-name*}

Modifies storage volumes on a node. Only LVM physical volumes can
be modified at the moment. They have a storage type of "lvm-pv".

Example::

    # gnt-node modify-storage --allocatable no node5.example.com lvm-pv /dev/sdb1


REPAIR-STORAGE
~~~~~~~~~~~~~~

**repair-storage** [--ignore-consistency] {*node*} {*storage-type*}
{*volume-name*}

Repairs a storage volume on a node. Only LVM volume groups can be
repaired at this time. They have the storage type "lvm-vg".

On LVM volume groups, **repair-storage** runs "vgreduce
--removemissing".



**Caution:** Running this command can lead to data loss. Use it with
care.

The ``--ignore-consistency`` option will ignore any inconsistent
disks (on the nodes paired with this one). Use of this option is
most likely to lead to data-loss.

Example::

    # gnt-node repair-storage node5.example.com lvm-vg xenvg


POWERCYCLE
~~~~~~~~~~

**powercycle** [``--yes``] [``--force``] {*node*}

This commands (tries to) forcefully reboot a node. It is a command
that can be used if the node environemnt is broken, such that the
admin can no longer login over ssh, but the Ganeti node daemon is
still working.

Note that this command is not guaranteed to work; it depends on the
hypervisor how effective is the reboot attempt. For Linux, this
command require that the kernel option CONFIG\_MAGIC\_SYSRQ is
enabled.

The ``--yes`` option can be used to skip confirmation, while the
``--force`` option is needed if the target node is the master
node.
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POWER
~~~~~

**power** on|off|cycle|status {*node*}

This commands calls out to out-of-band management to change the power
state of given node. With ``status`` you get the power status as reported
by the out-of-band managment script.