xenial (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.

       Apart from input data, hail collects data over the  network  from  all  MonDs  with  the  --mond  option.
       Currently it uses only data produced by the CPUload collector.

   ALGORITHM
       On  regular  node  groups, the program uses a simplified version of the hbal algorithm; for allocation on
       node groups with exclusive storage see below.

       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.

       For  allocation  on  node  groups with exclusive storage, the lost-allocations metrics is used instead to
       determine which node to allocate an instance on.  For a node the allocation vector is the vector of,  for
       each  instance policy interval in decreasing order, the number of instances minimally compliant with that
       interval that still can be placed on that node.  The lost-allocations vector for an instance on a node is
       the  difference  of  the  allocation  vectors for that node before and after placing the instance on that
       node.  The lost-allocations metrics is the lost allocation vector followed by the remaining disk space on
       the chosen node, all compared lexicographically.

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).

       --mond=*yes|no*
              If  given  the  program will query all MonDs to fetch data from the supported data collectors over
              the network.

       --mond-data datafile
              The name of the file holding the data provided  by  MonD,  to  override  quering  MonDs  over  the
              network.  This is mostly used for debugging.  The file must be in JSON format and present an array
              of JSON objects , one for every node, with two members.  The first member named node is  the  name
              of the node and the second member named reports is an array of report objects.  The report objects
              must be in the same format as produced by the monitoring agent.

       --ignore-dynu
              If given, all dynamic utilisation information will be ignored by assuming it to be 0.  This option
              will take precedence over any data passed by the MonDs with the --mond and the --mond-data option.

       --ignore-soft-errors
              If given, all checks for soft errors will be ommitted when searching for possible allocations.  In
              this way a useful decission can be made even in overloaded clusters.

       --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-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) 2006-2015 Google Inc.  All rights reserved.

       Redistribution and use in source and binary forms, with or without modification, are  permitted  provided
       that the following conditions are met:

       1.   Redistributions  of  source code must retain the above copyright notice, this list of conditions and
       the following disclaimer.

       2.  Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
       the following disclaimer in the documentation and/or other materials provided with the distribution.

       THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
       WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND  FITNESS  FOR  A
       PARTICULAR  PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
       ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY,  OR  CONSEQUENTIAL  DAMAGES  (INCLUDING,  BUT  NOT
       LIMITED  TO,  PROCUREMENT  OF  SUBSTITUTE  GOODS  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
       INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,  STRICT  LIABILITY,  OR
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