htools - Cluster allocation and placement tools for Ganeti



cluster balancer


cluster checker


cluster capacity computation


IAllocator plugin


saves cluster state for later reuse


cluster information printer


cluster rolling maintenance scheduler


htools is a suite of tools designed to help with allocation/movement of instances and balancing of Ganeti clusters. htools is also the generic binary that must be symlinked or hardlinked under each tool's name in order to perform the different functions. Alternatively, the environment variable HTOOLS can be used to set the desired role.

Installed as hbal, it computes and optionally executes a suite of instance moves in order to balance the cluster.

Installed as hcheck, it preforms cluster checks and optionally simulates rebalancing with all the hbal options available.

Installed as hspace, it computes how many additional instances can be fit on a cluster, while maintaining N+1 status. It can run on models of existing clusters or of simulated clusters.

Installed as hail, it acts as an IAllocator plugin, i.e. it is used by Ganeti to compute new instance allocations and instance moves.

Installed as hscan, it scans the local or remote cluster state and saves it to files which can later be reused by the other roles.

Installed as hinfo, it prints information about the current cluster state.

Installed as hroller, it helps scheduling maintenances that require node reboots on a cluster.


Options behave the same in all program modes, but not all program modes support all options. Some common options are:

-p, --print-nodes

Prints the node status, in a format designed to allow the user to understand the node's most important parameters. If the command in question makes a cluster transition (e.g. balancing or allocation), then usually both the initial and final node status is printed.

It is possible to customise the listed information by passing a comma-separated list of field names to this option (the field list is currently undocumented), or to extend the default field list by prefixing the additional field list with a plus sign. By default, the node list will contain the following information:


a character denoting the status of the node, with '-' meaning an offline node, '*' meaning N+1 failure and blank meaning a good node


the node name


the total node memory


the memory used by the node itself


the memory used by instances


amount memory which seems to be in use but cannot be determined why or by which instance; usually this means that the hypervisor has some overhead or that there are other reporting errors


the free node memory


the reserved node memory, which is the amount of free memory needed for N+1 compliance


total disk


free disk


the number of physical cpus on the node


the number of virtual cpus allocated to primary instances


number of primary instances


number of secondary instances


percent of free memory


percent of free disk


ratio of virtual to physical cpus


the dynamic CPU load (if the information is available)


the dynamic memory load (if the information is available)


the dynamic disk load (if the information is available)


the dynamic net load (if the information is available)

-t datafile, --text-data=datafile

Backend specification: the name of the file holding node and instance information (if not collecting via RAPI or LUXI). This or one of the other backends must be selected. The option is described in the man page htools(1).

The file should contain text data, line-based, with single empty lines separating sections. The lines themselves are column-based, with the pipe symbol (|) acting as separator.

The first section contains group data, with the following columns:

The second sections contains node data, with the following columns:

The third section contains instance data, with the fields:

The fourth section contains the cluster tags, with one tag per line (no columns/no column processing).

The fifth section contains the ipolicies of the cluster and the node groups, in the following format (separated by |):

-m cluster

Backend specification: collect data directly from the cluster given as an argument via RAPI. If the argument doesn't contain a colon (:), then it is converted into a fully-built URL via prepending https:// and appending the default RAPI port, otherwise it is considered a fully-specified URL and used as-is.

-L [path]

Backend specification: collect data directly from the master daemon, which is to be contacted via LUXI (an internal Ganeti protocol). An optional path argument is interpreted as the path to the unix socket on which the master daemon listens; otherwise, the default path used by Ganeti (configured at build time) is used.

-I|--ialloc-src path

Backend specification: load data directly from an iallocator request (as produced by Ganeti when doing an iallocator call). The iallocator request is read from specified path.

--simulate description

Backend specification: instead of using actual data, build an empty cluster given a node description. The description parameter must be a comma-separated list of five elements, describing in order:

An example description would be preferred,20,100G,16g,4,2 describing a 20-node cluster where each node has 100GB of disk space, 16GiB of memory, 4 CPU cores and 2 disk spindles. Note that all nodes must have the same specs currently.

This option can be given multiple times, and each new use defines a new node group. Hence different node groups can have different allocation policies and node count/specifications.

-v, --verbose

Increase the output verbosity. Each usage of this option will increase the verbosity (currently more than 2 doesn't make sense) from the default of one.

-q, --quiet

Decrease the output verbosity. Each usage of this option will decrease the verbosity (less than zero doesn't make sense) from the default of one.

-V, --version

Just show the program version and exit.


Some options accept not simply numerical values, but numerical values together with a unit. By default, such unit-accepting options use mebibytes. Using the lower-case letters of m, g and t (or their longer equivalents of mib, gib, tib, for which case doesn't matter) explicit binary units can be selected. Units in the SI system can be selected using the upper-case letters of M, G and T (or their longer equivalents of MB, GB, TB, for which case doesn't matter).

More details about the difference between the SI and binary systems can be read in the units(7) man page.


The environment variable HTOOLS can be used instead of renaming/symlinking the programs; simply set it to the desired role and then the name of the program is no longer used.


Report bugs to project website or contact the developers using the Ganeti mailing list.


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

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-storage(8) (storage commands), gnt-group(8) (node group 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).

Ganeti htools: htools(1) (generic binary), hbal(1) (cluster balancer), hspace(1) (capacity calculation), hail(1) (IAllocator plugin), hscan(1) (data gatherer from remote clusters), hinfo(1) (cluster information printer), mon-collector(7) (data collectors interface).


Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 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.