This patch adds an hscan tool that loads data from clusters via RAPI and
writes it to files that can be later used offline.

This patch does some small changes:
  - fixes a comment
  - export more node functions (unneeded now, but hscan will use them)
  - fixes Makefile rule for building the programs

This is added for better readability, since this is very often used in
declarations.

This patch changes two things with regard to offline nodes:
  - first, it only calculates the various coefficients across online
	nodes
  - second, it adds a new score denoting the percentage of instances
	which live on such nodes

The first change allows correct score computation in presence of offline
nodes (whose properties we don't need to take into account), while the
second change actively evacuates offline nodes.

This patch adds a new ‘-’ flag for the node status which denotes offline
nodes.

This patch changes the Cluster.checkInstanceMove function to restrict
the target move list based on which nodes are online.

This patch modifies hbal (only, hn1 not yet) for setting nodes offline.

This patch adds a new node attribute - offline - which will serve to
skip nodes from the target candidate list.

This will enhance the ‘dist’ rule by skipping unneeded files.

The modules are moved from the ‘top’ namespace to ‘Ganeti.HTools’, in
compliance with standard practices.

This patch moves the version string creation into a function in Utils
which shows some more information.

A new man page and typos fixed in hbal.1.

This patch adds a -V, --version command line option that shows the
program version and also updates the hn1 usage string (similar to hbal).

This just reorders some functions for a more logical ordering.

This patch changes the solution list to include a step counter so that
it's more clear these are successive steps (in a definite order), and
not just an unordered list of changes.

This patch changes the gnt-instance failover to migrate, and fixes a bug
in the formatting of commands.

This patch added a verbose output and changed the output so that by
default it is less verbose and more clear.

This patch adds a new instance move, FailoverAndReplace, which promotes
the old secondary to primary and then uses a new secondary node.

This is the last move that we can do within the limitations of one node
changed per move.

This patch moves the formatting of the command list to Cluster.hs and
enhances it with separator messages between the steps.

This patch adds a new replace secondary and failover move (equals to
“r:x f”), which can improve the solution (since we are testing more
options at each step).

Aligned the comments in Instance.hs

Currently hbal does multiple rounds, stopping when a rounds doesn't
bring improvements. With the recent changes to not remove instances from
the candidate list, this is obsolete as the first round will always run
to the end of the improvements.

This patch changes this so that the Cluster.checkMove function doesn't
recurse, but just computes the next best move (as its docstring says).
This means we can actually incrementally compute and print the solution,
and this is needed as otherwise an instance could move twice and the
second time it needs the current placement to compute the exact command
line and operation needed for the move.

This abstracts the individual placement solution so that it can be used
independently.

The current code restricts each instance to one move per round. This is
bad, as an computation restarted in the middle of the solution will have
a different set of instances to work and will thus lead to a different
end-solution.

Once this is applied, further rounds are not possible since the first
round will have tried all instances at its end. As such, the removal of
the rounds feature will be next.

The code adds a hard-coded 100 moves limit, which for big clusters is
actually small.

This prints the total memory/disk and also adds a header.

This is to keep in style with the other memory variables.

This is useful and not easy to compute otherwise.

This patch attempts to embed the VCS id in binaries, based on the way
other projects seem to do this.

This removes obsolete entries from the clean rule and adds the hbal
binary.

Since for a very many N+1 failures in a cluster, we could actually
degrade the N1 CV by making a node N+1 compliant, we need to make sure
this value only decreases when fixing non-compliant nodes.

The easiest way is to compute the N+1 score as a percentage of failed
nodes, with the caveat that the domain of values might not be fully
compatible with the other scores. It is still [0, 1] but does not vary
like the others.

This patch adds two new variables to the cluster score:
  - variance of the failN1 attribute
  - variance of the reserved memory percentage

The variance of the failN1 helps make the cluster N+1 happy, whereas the
reserved memory percentage helps balance the unused memory for
redundancy on the nodes.

This patch adds the node attribute “reserved memory percentage” that is
derived from the maximum reserved memory for a node and its total
memory.

This will be useful for enhancing the balancing algorithm.

This patch adds a score variable to the placement type, so we can record
the changes in the cluster CV for later display.

This gives visibility in the decrease of the parameters and can show
which are the most important steps to perform (out of the full move
list).