Provided by: ganeti-htools_2.9.3-1_amd64 bug

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.