trusty (1) hail.1.gz

NAME

       hail - Ganeti IAllocator plugin

SYNOPSIS

       hail [ -t file | --simulate spec ] [options...] input-file

       hail --version

DESCRIPTION

       hail  is  a  Ganeti  IAllocator plugin that implements the instance placement and movement using the same
       algorithm as hbal(1).

       The program takes input via a JSON-file containing current cluster state and  the  request  details,  and
       output (on stdout) a JSON-formatted response.  In case of critical failures, the error message is printed
       on stderr and the exit code is changed to show failure.

       If the input file name is - (a single minus sign), then the request data will be read from stdin.

   ALGORITHM
       The program uses a simplified version of the hbal algorithm.

       For single-node allocations (non-mirrored instances), again we select the node which, when chosen as  the
       primary node, gives the best score.

       For dual-node allocations (mirrored instances), we chose the best pair; this is the only choice where the
       algorithm is non-trivial with regard to cluster size.

       For relocations, we try to change the secondary node of the instance to all the valid  other  nodes;  the
       node which results in the best cluster score is chosen.

       For  node  changes  (change-node  mode),  we  currently  support DRBD instances only, and all three modes
       (primary changes, secondary changes and all node changes).

       For group moves (change-group mode), again only DRBD is supported, and we compute  the  correct  sequence
       that  will  result in a group change; job failure mid-way will result in a split instance.  The choice of
       node(s) on the target group is based on the group score, and the choice of group is  based  on  the  same
       algorithm as allocations (group with lowest score after placement).

       The deprecated multi-evacuate modes is no longer supported.

       In all cases, the cluster (or group) scoring is identical to the hbal algorithm.

OPTIONS

       The options that can be passed to the program are as follows:

       -p, --print-nodes
              Prints  the before and after node status, in a format designed to allow the user to understand the
              node's most important parameters.  See the man page htools(1) for more details about this option.

       -t datafile, --text-data=datafile
              The name of the file holding cluster information, to override the data in the JSON request itself.
              This is mostly used for debugging.  The format of the file is described in the man page htools(1).

       --simulate description
              Backend  specification:  similar  to the -t option, this allows overriding the cluster data with a
              simulated cluster.  For details about the description, see the man page htools(1).

       -S filename, --save-cluster=filename
              If given, the state of the cluster before and  the  iallocator  run  is  saved  to  a  file  named
              filename.pre-ialloc,  respectively filename.post-ialloc.  This allows re-feeding the cluster state
              to any of the htools utilities via the -t option.

       -v     This option increases verbosity and can be used for debugging  in  order  to  understand  how  the
              IAllocator request is parsed; it can be passed multiple times for successively more information.

CONFIGURATION

       For  the  tag-exclusion  configuration  (see  the  manpage  of  hbal for more details), the list of which
       instance tags to consider as exclusion tags will be read from the cluster tags, configured as follows:

       • get all cluster tags starting with htools:iextags:

       • use their suffix as the prefix for exclusion tags

       For example, given a cluster tag like htools:iextags:service, all instance tags  of  the  form  service:X
       will be considered as exclusion tags, meaning that (e.g.)
        two instances which both have a tag service:foo will not be placed on the same primary node.

OPTIONS

       The options that can be passed to the program are as follows:

EXIT STATUS

       The  exist  status of the command will be zero, unless for some reason the algorithm fatally failed (e.g.
       wrong node or instance data).

BUGS

       Networks (as configured by gnt-network(8)) are not taken into account in Ganeti 2.7.   The  only  way  to
       guarantee  that  they  work  correctly is having your networks connected to all nodegroups.  This will be
       fixed in a future version.

REPORTING BUGS

       Report bugs to project website (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-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

       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.