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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

add [ --readd ] [ -s secondary_ip ] nodename

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.

Example:

 # gnt-node add node5.example.com
 # gnt-node add -s 192.168.44.5 node5.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

list [ --sync ]
    [ --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.

By default, the query of nodes will be done in parallel with any running jobs. This might give inconsistent results for the free disk/memory. The --sync can be used to grab locks for all the nodes and ensure consistent view of the cluster (but this might stall the query for a long time).

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

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.

LIST-TAGS

list-tags nodename

List the tags of the given node.

MIGRATE

migrate [ -f ] [ --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 --no-live option can be given to do a non-live migration.

Example:

           # gnt-node migrate node1.example.com
         
 

MODIFY

modify [ -f ] [ --submit ] [ --master-candidate=yes|no ] [ --drained=yes|no ] [ --offline=yes|no ] [ --auto-promote ] 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 are described in the manpage ganeti(7).

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
         
 

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 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.

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.

REPORTING BUGS

Report bugs to <URL:http://code.google.com/p/ganeti/> or contact the developers using the ganeti mailing list <ganeti@googlegroups.com>.

SEE ALSO

Ganeti overview and specifications: ganeti(7) (general overview), ganeti-os-interface(7) (guest OS definitions).

Ganeti commands: gnt-cluster(8) (cluster-wide commands), gnt-job(8) (job-related commands), gnt-node(8) (node-related commands), gnt-instance(8) (instance commands), gnt-os(8) (guest OS commands), gnt-backup(8) (instance import/export commands), gnt-debug(8) (debug commands).

Ganeti daemons: ganeti-watcher(8) (automatic instance restarter), ganeti-cleaner(8) (job queue cleaner), ganeti-noded(8) (node daemon), ganeti-masterd(8) (master daemon), ganeti-rapi(8) (remote API daemon).

COPYRIGHT

Copyright (C) 2006, 2007, 2008, 2009 Google Inc. Permission is granted to copy, distribute and/or modify under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL.