Currently many of the exit and warning conditions mistakenly display error
messages on stdout, which makes parsing the output of programs harder. This
patch attempts to fix such occurrences.

Currently the cluster score calculation includes an offline instance
percentage, expressed as “offline inst / (offline + online inst)”, which
results in NaN for empty clusters. This patch changes the calculation
such that clusters with no offline instances (this criteria includes
completely empty clusters) get a score of zero on this component of the
total score.

Currently hspace exits with an error if the cluster is not N+1 compliant
at the beginning of the run. This patch changes hspace such that this
condition is instead treated as a zero-allocation-possible, FailN1 mode.
This allows the same stats to be reported in this case as in the normal
case.

This is mostly for user-friendliness in the default mode, when we don't
specify the instance parameters.

This patch optimizes the stdDev function in two respects:
  - first, we don't do sum . map which builds an intermediate list, but
	instead use a fold over the list to build incrementally the sum;
	this should reduce both the time and space characteristics, as we
	have fewer objects created
  - second, we move from “a ^ 2” to “a * a” as the latter has a much
	simpler implementation and thus a higher performance

Since the ‘square’ function is obsoleted by the above the patch also
removes it.

Currently Loader.fixNodes is foldl' with a complicated function. It
makes more sense to take foldl' out of this function (and put it into
the caller) and let fixNodes be only this internal function.

This patch changes the function Cluster.computeMoves to use guards and a
couple of subexpressions in order to greatly simplify it.

This big patch cleans up the code per hlint indications. Many removals
of extra parentheses, replacements of concat . map with concabtMap,
extra dollar signs, eta reductions, etc. were performed.

The code still compiles and passes a couple of manual tests on sample
files. The individual changes are also small enough as to be visually
easy to confirm.

This patch enhances hspace to report why the allocation sequence
stopped, both in absolute error count and for the top reason.

This patch alters the Node.addPri/addSec to return correct failure data.
It removes the computeFailN1 function from the module as that used to
combine both mem and disk checks in the same function and thus the real
error reason cannot be deduced when using it.

Currently the allocation/move operations workflow return ‘Maybe a’,
which is very convenient but loses all details about the failure mode.

This patch introduces a new data type which encodes the specific failure
mode. It is not yet used correctly (e.g. all node operations result in
FailN1), but the workflow is updated. Most of the changes are in the
hail/hspace tools, the library code required only trivial adjustments.

hn1 was deprecated for a while and this patch removes it altogether. The
support code in Cluster.hs is also removed.

This adds two new stats - sum of reserved ram and disk.

This uses the newly-added Node.availDisk to compute the actual available
disk correctl, and display the total allocatable disk in hspace.

This function returns the amount of available disk, which depends on
whether a low disk limit has been configured or not and on the free disk
space of the node.

Currently we track the max disk usage/max vcpus as percentages, however
sometimes it's easier to check against minimum free disk or maximum
number of cpus, as units instead of percentages.

This patch adds two new variables, lo_dsk, hi_cpu, which are recomputed
whenever we change the m_dsk/m_cpu 'master' values.

Currently totalResources returns a 5-tuple of integers. This is not easy
to handle, as each change on the return type means that each caller must
be updated.

This patch adds a new type for cluster stats and uses that instead as
its return type. This simplifies its callers while complicating only a
little the computation of the stats.

The display of cluster resources is extracted into a separate function
and enhanced to display more stats.

This patch changes Cluster.totalResources to compute more details about
the cluster status, and enhances hspace to display more of these.

Currently hscan has a number of bugs:
  - doesn't add the common suffix (csf) to the instance's nodes
  - doesn't export the cpus for neither nodes nor instances
  - doesn't support single-node instances

This patch fixes these issues.

We modify Node.addPri/addSec to take into account the limits on instance
adds.

Two new min disk free ratio and max cpu usage attributes are added to the
nodes. These will be used in the future to restrict allocation.

This removes some unused functions and imports to cleanup the warnings.

In a few places (e.g. tryRead or any printf call) it's a little bit hard
to add the correct type signatures, but in the it is possible to fix
these warnings (which can bite one in subtle cases).

This is just some cleanup of the node list output, adding pcpu/vcpu
counters, and making the display slightly nicer.

The cpu counters are update on primary instance adds/removes.

This patch adds cpu-count related attributes to nodes:
  - total cpus
  - cpus in use
  - ratio of virtual:physical cpus

We also set correctly the cpu values at load time, but we don't do
anything yet while moving instances around. The cpu ratio is shown in
the cluster list.

This patch adds reading of vcpu count for instances, in preparation for
using the vcpu ratio in cluster scoring.

IAllocator currently uses a wrong key name for reading the total disk
space (‘disk_usage’ which was copied from RAPI, but the actual
iallocator key is ‘disk_space_total’).

This patch fixes that and also makes iallocator always use this key,
instead of computing the size by itself—with Ganeti 2.0 this is
key is always available.

Small updates to the documentation and make a new small release.

During a replace-primary instance move, on the real cluster the instance
is temporarily started on the secondary, and as such we must check that
the secondary node can hold it for this duration. Currently the code
does not, and depending on cluster scoring it will put instances on such
'bad' secondaries (usually without enough memory).

This patch fixes this by adding/removing the instance as a primary on
the secondary node; and then using the result node as the new secondary.
(Since we're in a monad, we could have just tried the allocation and
dropped the result, but this is more clear).