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Ganeti-htools release notes

===========================

Version 0.2.7 (Unreleased)

--------------------------

Bug fixes:

- fixed the error message for hail multi-evacuation mode

New features:

- add a new option ``-S`` to hbal and hspace that saves the cluster

  state at the end of the processing in the text format used by the

  ``-t`` option, for later re-processing

Version 0.2.6 (Mon, 26 Jul 2010)

--------------------------------

Exactly three months since the last release. Many internal changes, plus

a couple of important changes in the balancing algorithm.

First, the balancing may now introduce N+1 errors, if this solves other,

more critical problems. For the moment, this means that moving instances

away from offline nodes is allowed even if it creates N+1 errors, and

that means evacuation can be done in more cases.

Second, the scoring for N+1 has changed. In previous versions, it simply

counted the number of failing N+1 nodes, which means moving an instance

away from a N+1 failed node (but without the node 'clearing' the N+1

status) was not reflected in the cluster score. As such, the balancing

algorithm managed to clear N+1 errors only sometimes, since usually it

takes more than one move for this, and the first prerequisite move was

not 'rewarded' appropriately and thus it was not selected. Now, it is

possible to fix many more error cases than before: on a simulated 40

node cluster full with instances (symmetrically allocated on all nodes),

around five nodes can be evacuated before N+1 errors can be solved,

whereas 0.2.5 could evacuate at best one node.

There were some other internal changes to the scoring algorithm, such

that now the metrics have associated weights, and they are not all of

the same importance anymore. As of now, the only change is that offline

instances have a higher weight, which should favour proper node

evacuations.

Among the other changes:

- fixed the hspace KM_POOL_* metrics, which were returned as the final

  state and not as the delta between the initial and final states

- fixed hspace handling of N+1 failing clusters: before, it used to

  generate a 'fake' response, and the structure of this response was not

  always in sync with the real responses, leading to missing items;

  currently it proceeds correctly through the code (skipping the

  computation), and uses the same display mechanisms as the normal case

- fixed hscan exit code for RAPI failures: previously it finished with

  success even if all the clusters failed, which was creating issues

  with the live-test script; now it exits with exit code 2 for RAPI

  failures (unfortunately this is still not optimal as LUXI failures

  will use exit code 1, the same as the command line)

- changed the limit values for CPU/disk, which previously were used

  optionally, whereas now they are always used; the default cpu ratio

  limit is now 64 VCPUs per PCPU

- changed the internal handling of the short name vs. original

  (Ganeti-provided) name; now internally we always use the full name,

  and only in display routines we show the shortened (called 'alias')

  name; as a result, the -O and --excluded-instances options now accept

  both the full name and the shortened name

- changed internal handling of JSON conversions and errors, such that

  now we show a better context for failure messages, which should help

  with diagnosing the malformed message

- changed the names for a few node fields, and added some more nodes;

  this is most likely to help with debugging, and not with regular

  operation though

- changed the node fields option to allow the '+' prefix to mean 'extend

  the default fields list' rather than start from fresh (similar to

  Ganeti's implementation)

- a few internal changes related to the LUXI protocol implementation,

  which should make it more safe against potential bugs, one

  optiomization that should help with large messages, and some patches

  in preparation for potential expansion of the LUXI backend functionality

And finally, many improvements on unittests and the live-test

script. Test coverage is much enhanced, and the test infrastructure has

better error reporting; this should lead down-the-road to better code

and fewer bugs…

Version 0.2.5 (Mon, 26 Apr 2010)

--------------------------------

Some internal cleanup plus a few user-visible changes:

- new option for marking instances as 'do-not-move' during rebalancing

- allow ``hscan`` to scan the local cluster via Luxi

- add more metrics to ``hspace`` which show the delta between original

  state and final state better (only valid for tiered allocation)

Version 0.2.4 (Mon, 22 Feb 2010)

--------------------------------

Two improvements for node evacuation:

- hbal takes a new parameter ``--evac-mode`` that restricts the

  instances to be moved to the ones on offline/drained nodes, which

  should reduce the work done

- hail supports the new ``multi-evacuate`` mode of the IAllocator

  protocol, that will be released in a minor release on the Ganeti 2.1

  branch

Version 0.2.3 (Thu,  4 Feb 2010)

--------------------------------

A small release:

- Fixes selection of secondary node: previously, if the cluster had

  many N+1 failures, a N+1 failed node could be selected as secondary

  even if it did not have enough memory to allow the instance to be

  migrated/failed over to it; this is bad for automated tools, since

  we can get the cluster in an unhealthy state

- Switch the text backend to a single input file, that is generated

  now by hscan and shouldn't be generated manually via

  gnt-node/instance list anymore; this allows richer information to be

  kept in the file, and simplifies a little the internals of the text

  backend

Version 0.2.2 (Tue, 29 Dec 2009)

--------------------------------

Small release, 0.2.1 was broken and thus this was released earlier:

- Release 0.2.1 broke the LUXI backend due to a typo, fixed

- Added a live-test script that should catch errors like the above one

  in the future (needs a working, non-empty cluster)

- Changed RAPI and LUXI backends to treat drained nodes as offline,

  similar to the IAllocator backend change in 0.2.0 (which was wrongly

  marked as affecting all backends)

- Changed the metrics for offline instances and N1 score from percent to

  count, in order to increase the priority of evacuations

- Added a new metric (offline primary instances) which should fix the

  evacuation of a offline node in a 2-node cluster

Version 0.2.1 (Wed,  2 Dec 2009)

--------------------------------

- Added instance exclusion defined via instance tags

- Fixed the output of hspace to be again parseable from the shell

Version 0.2.0 (Tue, 10 Nov 2009)

--------------------------------

A significant release, with a few new major features:

- Added direct execution of the hbal solution when using the Luxi

  backend; the steps for each instance moves are submitted as a single

  jobs, and the different jobs are submitted as groups in order to

  parallelise the execution of moves

- Added support for balancing based on dynamic utilisation data for

  instances, fed in via a text file; by default, all instances are

  considered equal and this change also improves the equalisation of

  secondary instances per node

- Added support for tiered capacity calculation in hspace, where we

  start from a maximum instance spec and decrease the spec when we run

  out of resources; this should give a better measure of available

  capacity on 'fragmented' clusters; this is done separately from the

  current fixed-mode computation

Also there have been many minor improvements:

- Added option for showing instances (“--print-instances”), similar to

  the print nodes option

- Added support for customising the node list via an argument to the

  print nodes option in the form of a comma-separated list of field

  names; currently the field names are not documented, expecting further

  changes in a next release

- Enhanced the error reporting in the Luxi and Rapi backends

- Changed the handling of drained nodes, now being treated the same as

  offline nodes, for Ganeti 2.0.4+ compatibility

- A number of internal changes, simplifying code and merging some

  disparate functions

- Simplify the build system in relation to creation of archives

Version 0.1.8 (Tue, 29 Sep 2009)

--------------------------------

- Brown-paper-bag release fixing haddock issues

Version 0.1.7 (Mon, 28 Sep 2009)

--------------------------------

- Fixed a bug in the Luxi backend for big responses

- Fixed test suite exit code in presence of test failures

- Changed the migrate operation to run instead failover for instances

  which were marked as not running in the input data (this could have

  been changed since then, but it's better than today's always migrate)

- Added support for 'cheap' moves only (only migrate/failover) in

  balancing

- Added support for building without curl (thus no RAPI backend)

Version 0.1.6 (Wed, 19 Aug 2009)

--------------------------------

- Added support for Luxi (the native Ganeti protocol)

- Added support for simulated clusters (for hspace only)

- Added timeouts for the RAPI backend

- Fixed a few inconsistencies in the command line handling

- Fixed handling of errors while loading data

- The 'network' is a new dependency due to the Luxi addition

Version 0.1.5 (Thu, 09 Jul 2009)

--------------------------------

- Removed obsolete hn1 program; this allowed removal of a lot of

  supporting code

- Lots of changes in hspace: the output now is a shell fragment in order

  for script to source it or parse it easier; added failure reasons;

  optimised to use less memory for large clusters

- Optimized the scoring algorithm (used by all tools) so that now

  computations should be faster

Version 0.1.4 (Tue, 16 Jun 2009)

--------------------------------

- Added CPU count/ratio of virtual-to-physical CPUs to the cluster

  scoring methods; this means that now the balancer, the iallocator

  plugin and so on will try to keep the VCPU-to-PCPU ratio equal across

  the cluster

- Fixed some hscan bugs

- Fixed the way iallocator reads the total disk size (was broken and it

  was always falling back to summing the disk sizes)

- Internals: fixed most compile-time warnings

Version 0.1.3 (Fri, 05 Jun 2009)

--------------------------------

- Fix a bug in the ReplacePrimary instance moves, affecting most of the

  tools

Version 0.1.2 (Tue, 02 Jun 2009)

--------------------------------

- Add a new program, “hspace”, which computes the free space on a

  cluster (based on a given instance spec)

- Improvements in API docs and partially in the user docs

- Started adding unittests

Version 0.1.1 (Tue, 26 May 2009)

--------------------------------

- Add a new program, “hail”, which is an iallocator plugin and can

  allocate/relocate instances

- Experimental support for non-mirrored instances (hail supports them,

  hbal should no longer abort when it finds such instances and simply

  ignore them)

- The RAPI port and/or scheme can be overriden now, and even “file://”

  schemes can be used if the message body has been saved under the

  appropriate name

- Lots of code reorganization, esp. rewritten loading pipeline

- Better data checking and better error messages in case validation

  fails; tools now consider nodes with error in input data (‘?’ returned

  by ganeti) as offline

- Small enhancement to the makefile for simpler packaging

Version 0.1.0 (Tue, 19 May 2009)

--------------------------------

- Drop compatibility with Ganeti 1.2

- Add a new minimum score option (with a very low default), should help

  with very good clusters (but is still not optimal)

- Add a --quiet option to hbal

- Add support for reading offline nodes directly from the cluster

Version 0.0.8 (Tue, 21 Apr 2009)

--------------------------------

- hbal: prevent mismatches in wrong node names being passed to -O, by

  aborting in this case

- add the ability to write the commands (-C) to a script via (-C<file>),

  so that it can be later executed directly; this has also changed the

  commands to include the ncessary -f flags to skip confirmations

- add checks for extra argument in hbal and hn1, so that unintended

  errors are catched

- raise the accepted “missing” memory limit to 512MB, to cover usual Xen

  reservations

Version 0.0.7 (Mon, 23 Mar 2009)

--------------------------------

- added support for offline nodes, which are not used as targets for

  instance relocation and if they hold instances the hbal algorithm will

  attempt to relocate these away

- added support for offline instances, which now will no longer skew the

  free memory estimation of nodes; the algorithm will no longer create

  conditions for N+1 failures when such instances are later started

- implemented a complete model of node resources, in order to prevent an

  unintended re-occurrence of cases like the offline instance were we

  miscalculate some node resource; this gives warning now in case the

  node reported free disk or free memory deviates by more than a set

  amount from the expected value

- a new tool *hscan* that can generate the input text-file for the other

  tools by collection via RAPI

- some small changes to the build system to make it more friendly; also

  included the generated documentation in the source archive

Version 0.0.6 (Mon, 16 Mar 2009)

--------------------------------

- re-factored the hbal algorithm to make it stable in the sense that it

  gives the same solution when restarted from the middle; barring

  rounding of disk/memory and incomplete reporting from Ganeti (for

  1.2), it should be now feasible to rely on its output without

  generating moves ad infinitum

- the hbal algorithm now uses two more variables: the node N+1 failures

  and the amount of reserved memory; the first of which tries to ‘fix’

  the N+1 status, the latter tries to distribute secondaries more

  equally

- the hbal algorithm now uses two more moves at each step:

  replace+failover and failover+replace (besides the original failover,

  replace, and failover+replace+failover)

- slightly changed the build system to embed GIT version/tags into the

  binaries so that we know for a binary from which tree it was done,

  either via ‘--version’ or via “strings hbal|grep version”

- changed the solution list and in general the hbal output to be more

  clear by default, and changed “gnt-instance failover” to “gnt-instance

  migrate”

- added man pages for the two binaries

Version 0.0.5 (Mon, 09 Mar 2009)

--------------------------------

- a few small improvements for hbal (possibly undone by later changes),

  hbal is now quite faster

- fix documentation building

- allow hbal to work on non N+1 compliant clusters, but without

  guarantees that the end cluster will be compliant; in any case, this

  should give a smaller number of nodes that are not compliant if the

  cluster state permits it

- strip common domain suffix from nodes and instances, so that output is

  shorter and hopefully clearer

Version 0.0.4 (Sun, 15 Feb 2009)

--------------------------------

- better balancing algorithm in hbal

- implemented an RAPI collector, now the cluster data can be gathered

  automatically via RAPI and doesn't need manual export of node and

  instance list

Version 0.0.3 (Wed, 28 Jan 2009)

--------------------------------

- initial release of the hbal, a cluster rebalancing tool

- input data format changed due to hbal requirements

Version 0.0.2 (Tue, 06 Jan 2009)

--------------------------------

- fix handling of some common cases (cluster N+1 compliant from the

  start, too big depth given, failure to compute solution)

- add option to print the needed command list for reaching the proposed

  solution

Version 0.0.1 (Tue, 06 Jan 2009)

--------------------------------

- initial release of hn1 tool

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