gnt-node¶
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¶
Adds the given node to the cluster.
This command is used to join a new node to the cluster. You will
have to provide credentials to ssh as root to the node to be added.
Forwarding of an ssh agent (the -A option of ssh) works, if an
appropriate authorized key is set up on the node to be added. If
the other node allows password authentication for root, another
way of providing credentials is to provide the root password once
asked for it. 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 to the cluster, not paying attention to its current status (it could be already in a cluster, etc.)
The -s (--secondary-ip) 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 re-adding 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 be reused from the cluster. Also, the
drained and offline flags of the node will be cleared before
re-adding it. Note that even for re-added nodes, a new SSH key is
generated and distributed and previous Ganeti keys are removed
from the machine.
The -g (--node-group) option 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.
The --no-node-setup option that used to prevent Ganeti from performing
the initial SSH setup on the new node is no longer valid. Instead,
Ganeti considers the modify ssh setup configuration parameter
(which is set using --no-ssh-init during cluster initialization)
to determine whether or not to do the SSH setup on a new node or not.
If this parameter is set to False, Ganeti will not touch the SSH
keys or the authorized_keys file of the node at all. Using this option,
it lies in the administrators responsibility to ensure SSH connectivity
between the hosts by other means.
The vm_capable, master_capable, ndparams, diskstate and
hvstate options are described in ganeti(7), and are used to set
the properties of the new node.
The command performs some operations that change the state of the master
and the new node, like copying certificates and starting the node daemon
on the new node, or updating /etc/hosts on the master node. If the
command fails at a later stage, it doesn’t undo such changes. This
should not be a problem, as a successful run of gnt-node add will
bring everything back in sync.
If the node was previously part of another cluster and still has daemons
running, the node-cleanup tool can be run on the machine to be added
to clean remains of the previous cluster from the node.
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
EVACUATE¶
This command will move instances away from the given node. If
--primary-only is given, only primary instances are evacuated, with
--secondary-only only secondaries. If neither is given, all
instances are evacuated. 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
-n (--new-secondary)option - or via the
-I (--iallocator)option, giving a script name as parameter (or.to use the default allocator), 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).
Note that this command is equivalent to using per-instance commands for each affected instance individually:
--primary-onlyis equivalent to performinggnt-instance migratefor every primary instance running on the node that can be migrated andgnt-instance failoverfor every primary instance that cannot be migrated.--secondary-onlyis equivalent tognt-instance replace-disksin secondary node change mode (--new-secondary) for every DRBD instance that the node is a secondary for.- when neither of the above is done a combination of the two cases is run
Note that the iallocator currently only considers disk information of the default disk template, even if the instance’s disk templates differ from that.
The --ignore-soft-errors option is passed through to the allocator.
See ganeti(7) for a description of --submit and other common
options.
Example:
# gnt-node evacuate -I hail node3.example.com
Note that, due to an issue with the iallocator interface, evacuation of all instances at once is not yet implemented. Full evacuation can currently be achieved by sequentially evacuating primaries and secondaries.
# gnt-node evacuate -p node3.example.com
# gnt-node evacuate -s 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.
Note that failover will stop any running instances on the given node and restart them again on the new primary. See also FAILOVER in gnt-instance(8).
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¶
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.
Queries of nodes will be done in parallel with any running jobs. This might give inconsistent results for the free disk/memory.
The -v option activates verbose mode, which changes the display of
special field states (see ganeti(7)).
The -o (--output) option takes a comma-separated list of output
fields. The available fields and their meaning are:
bootid- Random UUID renewed for each system reboot, can be used for detecting reboots by tracking changes
cnodes- Number of NUMA domains on node (if exported by hypervisor)
cnos- Number of logical processors used by the node OS (dom0 for Xen)
csockets- Number of physical CPU sockets (if exported by hypervisor)
ctime- Creation timestamp
ctotal- Number of logical processors
custom_ndparams- Custom node parameters
dfree- Available storage space in storage unit
disk_state- Disk state
drained- Whether node is drained
dtotal- Total storage space in storage unit used for instance disk allocation
group- Node group
group.uuid- UUID of node group
hv_state- Hypervisor state
master- Whether node is master
master_candidate- Whether node is a master candidate
master_capable- Whether node can become a master candidate
mfree- Memory available for instance allocations
mnode- Amount of memory used by node (dom0 for Xen)
mtime- Modification timestamp
mtotal- Total amount of memory of physical machine
name- Node name
ndp/cpu_speed- The “cpu_speed” node parameter
ndp/exclusive_storage- The “exclusive_storage” node parameter
ndp/oob_program- The “oob_program” node parameter
ndp/ovs- The “ovs” node parameter
ndp/ovs_link- The “ovs_link” node parameter
ndp/ovs_name- The “ovs_name” node parameter
ndp/spindle_count- The “spindle_count” node parameter
ndp/ssh_port- The “ssh_port” node parameter
ndparams- Merged node parameters
offline- Whether node is marked offline
pinst_cnt- Number of instances with this node as primary
pinst_list- List of instances with this node as primary
pip- Primary IP address
powered- Whether node is thought to be powered on
role- Node role; “M” for master, “C” for master candidate, “R” for regular, “D” for drained, “O” for offline
serial_no- Node object serial number, incremented on each modification
sinst_cnt- Number of instances with this node as secondary
sinst_list- List of instances with this node as secondary
sip- Secondary IP address
spfree- Available spindles in volume group (exclusive storage only)
sptotal- Total spindles in volume group (exclusive storage only)
tags- Tags
uuid- Node UUID
vm_capable- Whether node can host instances
If the value of the option starts with the character +, the new
fields will be added to the default list. This allows one to quickly
see the default list plus a few other fields, instead of retyping
the entire list of fields.
Note that some of these 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 require a query to the cluster nodes.
Depending on the virtualization type and implementation details, the
mtotal, mnode and mfree fields may have slightly 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).
Note that the field ‘dtotal’ and ‘dfree’ refer to the storage type
that is defined by the default disk template. The default disk template
is the first on in the list of cluster-wide enabled disk templates and
can be set with gnt-cluster modify. Currently, only the disk
templates ‘plain’, ‘drbd’, ‘file’, and ‘sharedfile’ support storage
reporting, for all others ‘0’ is displayed.
If exactly one argument is given and it appears to be a query filter
(see ganeti(7)), the query result is filtered accordingly. For
ambiguous cases (e.g. a single field name as a filter) the --filter
(-F) option forces the argument to be treated as a filter (e.g.
gnt-node list -F master_candidate).
If no node names are given, then all nodes are queried. Otherwise, only the given nodes will be listed.
LIST-DRBD¶
list-drbd [–no-headers] [–separator=*SEPARATOR*] node
Lists the mapping of DRBD minors for a given node. This outputs a static
list of fields (it doesn’t accept the --output option), as follows:
Node- The (full) name of the node we are querying
Minor- The DRBD minor
Instance- The instance the DRBD minor belongs to
Disk- The disk index that the DRBD minor belongs to
Role- Either
primaryorsecondary, denoting the role of the node for the instance (note: this is not the live status of the DRBD device, but the configuration value) PeerNode- The node that the minor is connected to on the other end
This command can be used as a reverse lookup (from node and minor) to a given instance, which can be useful when debugging DRBD issues.
Note that this command queries Ganeti via ganeti-confd(8), so
it won’t be available if support for confd has not been enabled at
build time; furthermore, in Ganeti 2.6 this is only available via the
Haskell version of confd (again selected at build time).
MIGRATE¶
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, --migration-mode and --no-runtime-changes
can be given to influence the migration type.
If --ignore-ipolicy is given any instance policy violations
occurring during this operation are ignored.
See ganeti(7) for a description of --submit and other common
options.
Example:
# gnt-node migrate node1.example.com
MODIFY¶
yes|no]yes|no] [{-O|–offline} yes|no]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).
The option --node-powered can be used to modify state-of-record if
it doesn’t reflect the reality anymore.
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 (--secondary-ip) option 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. Remember that the secondary ip must be
reachable from the master secondary ip, when being changed, so be sure
that the node has the new IP already configured and active. In order to
convert a cluster from single homed to multi-homed or vice versa
--force is needed as well, and the target node for the first change
must be the master.
See ganeti(7) for a description of --submit and other common
options.
Example (setting the node back to online and master candidate):
# gnt-node modify --offline=no --master-candidate=yes node1.example.com
REMOVE¶
remove {node-name}
Removes a node from the cluster. Instances must be removed or migrated to another cluster before.
Example:
# gnt-node remove node5.example.com
VOLUMES¶
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 (--output) 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¶
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, file, sharedfile and gluster.
The -o (--output) 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¶
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¶
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] [–submit] [–print-jobid] {node-name}
This command (tries to) forcefully reboot a node. It is a command that can be used if the node environment 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 requires the kernel option CONFIG_MAGIC_SYSRQ to be
enabled.
The --yes option can be used to skip confirmation, while the
--force option is needed if the target node is the master
node.
See ganeti(7) for a description of --submit and other common
options.
POWER¶
power [--force] [--ignore-status] [--all]
[--power-delay] on|off|cycle|status [node-name...]
This command 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 management script.
Note that this command will only work if the out-of-band functionality is configured and enabled on the cluster. If this is not the case, please use the powercycle command above.
Currently this only has effect for off and cycle. For safety,
Ganeti will not allow either of these operations to be run on the master
node. However, it will print a command line which can then be run
manually on the master. Note that powering off the master is potentially
dangerous, and Ganeti does not support doing this.
Providing --force will skip confirmations for the operation.
Providing --ignore-status will ignore the offline=N state of a node
and continue with power off.
--power-delay specifies the time in seconds (factions allowed)
waited between powering on the next node. This is by default 2 seconds
but can increased if needed with this option.
The list of node names is optional. If not provided it will call out for every
node in the cluster. Except for the off and cycle command where you’ve
to explicit use --all to select all.
HEALTH¶
health [node-name...]
This command calls out to out-of-band management to ask for the health status
of all or given nodes. The health contains the node name and then the items
element with their status in a item=status manner. Where item is script
specific and status can be one of OK, WARNING, CRITICAL or
UNKNOWN. Items with status WARNING or CRITICAL are logged and
annotated in the command line output.
RESTRICTED-COMMAND¶
Executes a restricted command on the specified nodes. Restricted commands are
not arbitrary, but must reside in
/etc/ganeti/restricted-commands on a node, either as a regular
file or as a symlink. The directory must be owned by root and not be
world- or group-writable. If a command fails verification or otherwise
fails to start, the node daemon log must be consulted for more detailed
information.
Example for running a command on two nodes:
# gnt-node restricted-command mycommand \
node1.example.com node2.example.com
The -g option can be used to run a command only on a specific node
group, e.g.:
# gnt-node restricted-command -g default mycommand
The -M option can be used to prepend the node name to all command
output lines. --sync forces the opcode to acquire the node lock(s)
in exclusive mode.
Tags¶
ADD-TAGS¶
add-tags [–from file] {node-name} {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.
REMOVE-TAGS¶
remove-tags [–from file] {node-name} {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.