hspace - Cluster space analyzer for Ganeti
hspace [backend options...] [algorithm options...] [request
options... ] [ -p[fields] ] [-v... | -q]
-m cluster | -L[path] | -t data-file | --simulate spec
[ --max-cpu cpu-ratio ] [ --min-disk disk-ratio ] [ -O name... ]
[--memory mem] [--disk disk] [--req-nodes req-nodes] [--vcpus
vcpus] [--tiered-alloc spec]
hspace computes how many additional instances can be fit on a cluster,
while maintaining N+1 status.
The program will try to place instances, all of the same size, on the
cluster, until the point where we don’t have any N+1 possible
allocation. It uses the exact same allocation algorithm as the hail
The output of the program is designed to interpreted as a shell
fragment (or parsed as a key=value file). Options which extend the
output (e.g. -p, -v) will output the additional information on stderr
(such that the stdout is still parseable).
The following keys are available in the output of the script (all
prefixed with HTS_):
SPEC_MEM, SPEC_DSK, SPEC_CPU, SPEC_RQN
These represent the specifications of the instance model used
for allocation (the memory, disk, cpu, requested nodes).
CLUSTER_MEM, CLUSTER_DSK, CLUSTER_CPU, CLUSTER_NODES
These represent the total memory, disk, CPU count and total
nodes in the cluster.
These are the initial (current) and final cluster score (see the
hbal man page for details about the scoring algorithm).
The initial and final instance count.
The initial and final total free memory in the cluster (but this
doesn’t necessarily mean available for use).
The initial and final total available memory for allocation in
the cluster. If allocating redundant instances, new instances
could increase the reserved memory so it doesn’t necessarily
mean the entirety of this memory can be used for new instance
The initial and final reserved memory (for redundancy/N+1
The initial and final memory used for instances (actual runtime
The initial and final memory overhead — memory used for the node
itself and unacounted memory (e.g. due to hypervisor overhead).
The initial and final memory efficiency, represented as instance
memory divided by total memory.
INI_DSK_FREE, INI_DSK_AVAIL, INI_DSK_RESVD, INI_DSK_INST, INI_DSK_EFF
Initial disk stats, similar to the memory ones.
FIN_DSK_FREE, FIN_DSK_AVAIL, FIN_DSK_RESVD, FIN_DSK_INST, FIN_DSK_EFF
Final disk stats, similar to the memory ones.
Initial and final number of virtual CPUs used by instances.
The initial and final CPU efficiency, represented as the count
of virtual instance CPUs divided by the total physical CPU
The initial and final maximum per‐node available memory. This is
not very useful as a metric but can give an impression of the
status of the nodes; as an example, this value restricts the
maximum instance size that can be still created on the cluster.
Like the above but for disk.
TSPEC If the tiered allocation mode has been enabled, this parameter
holds the pairs of specifications and counts of instances that
can be created in this mode. The value of the key is a
space‐separated list of values; each value is of the form
memory,disk,vcpu=count where the memory, disk and vcpu are the
values for the current spec, and count is how many instances of
this spec can be created. A complete value for this variable
could be: 4096,102400,2=225 2560,102400,2=20 512,102400,2=21.
KM_USED_CPU, KM_USED_MEM, KM_USED_DSK
These represents the metrics of used resources at the start of
the computation (only for tiered allocation mode).
KM_POOL_CPU, KM_POOL_MEM, KM_POOL_DSK
These represents the total resources allocated during the tiered
allocation process. In effect, they represent how much is
readily available for allocation.
KM_UNAV_CPU, KM_UNAV_MEM, KM_UNAV_DSK
These represents the resources left over (either free as in
unallocable or allocable on their own) after the tiered
allocation has been completed. They represent better the actual
unallocable resources, because some other resource has been
exhausted. For example, the cluster might still have 100GiB disk
free, but with no memory left for instances, we cannot allocate
another instance, so in effect the disk space is unallocable.
Note that the CPUs here represent instance virtual CPUs, and in
case the --max-cpu option hasn’t been specified this will be -1.
The current usage represented as initial number of instances
divided per final number of instances.
The number of instances allocated (delta between FIN_INST_CNT
For the last attemp at allocations (which would have increased
FIN_INST_CNT with one, if it had succeeded), this is the count
of the failure reasons per failure type; currently defined are
FAILMEM, FAILDISK and FAILCPU which represent errors due to not
enough memory, disk and CPUs, and FAILN1 which represents a non
N+1 compliant cluster on which we can’t allocate instances at
The reason for most of the failures, being one of the above
OK A marker representing the successful end of the computation, and
having value "1". If this key is not present in the output it
means that the computation failed and any values present should
not be relied upon.
If the tiered allocation mode is enabled, then many of the INI_/FIN_
metrics will be also displayed with a TRL_ prefix, and denote the
cluster status at the end of the tiered allocation run.
The options that can be passed to the program are as follows:
The memory size of the instances to be placed (defaults to
The disk size of the instances to be placed (defaults to
The number of nodes for the instances; the default of two means
mirrored instances, while passing one means plain type
The number of VCPUs of the instances to be placed (defaults to
The maximum virtual‐to‐physical cpu ratio, as a floating point
number between zero and one. For example, specifying cpu-ratio
as 2.5 means that, for a 4‐cpu machine, a maximum of 10 virtual
cpus should be allowed to be in use for primary instances. A
value of one doesn’t make sense though, as that means no disk
space can be used on it.
The minimum amount of free disk space remaining, as a floating
point number. For example, specifying disk-ratio as 0.25 means
that at least one quarter of disk space should be left free on
Prints the before and after node status, in a format designed to
allow the user to understand the node’s most important
It is possible to customise the listed information by passing a
comma‐separated list of field names to this option (the field
list is currently undocumented). By default, the node list will
contain these informations:
F a character denoting the status of the node, with ’-’
meaning an offline node, ’*’ meaning N+1 failure and
blank meaning a good node
Name the node name
t_mem the total node memory
n_mem the memory used by the node itself
i_mem the memory used by instances
x_mem amount memory which seems to be in use but cannot be
determined why or by which instance; usually this means
that the hypervisor has some overhead or that there are
other reporting errors
f_mem the free node memory
r_mem the reserved node memory, which is the amount of free
memory needed for N+1 compliance
t_dsk total disk
f_dsk free disk
pcpu the number of physical cpus on the node
vcpu the number of virtual cpus allocated to primary instances
pri number of primary instances
sec number of secondary instances
p_fmem percent of free memory
p_fdsk percent of free disk
r_cpu ratio of virtual to physical cpus
lCpu the dynamic CPU load (if the information is available)
lMem the dynamic memory load (if the information is available)
lDsk the dynamic disk load (if the information is available)
lNet the dynamic net load (if the information is available)
This option (which can be given multiple times) will mark nodes
as being offline, and instances won’t be placed on these nodes.
Note that hspace will also mark as offline any nodes which are
reported by RAPI as such, or that have "?" in file‐based input
in any numeric fields.
The name of the file holding node and instance information (if
not collecting via RAPI or LUXI). This or one of the other
backends must be selected.
Collect data directly from the cluster given as an argument via
RAPI. If the argument doesn’t contain a colon (:), then it is
converted into a fully‐built URL via prepending https:// and
appending the default RAPI port, otherwise it’s considered a
fully‐specified URL and is used as‐is.
Collect data directly from the master daemon, which is to be
contacted via the luxi (an internal Ganeti protocol). An
optional path argument is interpreted as the path to the unix
socket on which the master daemon listens; otherwise, the
default path used by ganeti when installed with
--localstatedir=/var is used.
Instead of using actual data, build an empty cluster given a
node description. The description parameter must be a
comma‐separated list of four elements, describing in order:
the number of nodes in the cluster
the disk size of the nodes, in mebibytes
the memory size of the nodes, in mebibytes
the cpu core count for the nodes
An example description would be 20,102400,16384,4 describing a
20‐node cluster where each node has 100GiB of disk space, 16GiB
of memory and 4 CPU cores. Note that all nodes must have the
same specs currently.
Beside the standard, fixed‐size allocation, also do a tiered
allocation scheme where the algorithm starts from the given
specification and allocates until there is no more space; then
it decreases the specification and tries the allocation again.
The decrease is done on the matric that last failed during
allocation. The specification given is similar to the --simulate
option and it holds:
the disk size of the instance
the memory size of the instance
the vcpu count for the insance
An example description would be 10240,8192,2 describing an
initial starting specification of 10GiB of disk space, 4GiB of
memory and 2 VCPUs.
Also note that the normal allocation and the tiered allocation
are independent, and both start from the initial cluster state;
as such, the instance count for these two modes are not related
one to another.
Increase the output verbosity. Each usage of this option will
increase the verbosity (currently more than 2 doesn’t make
sense) from the default of one. At verbosity 2 the location of
the new instances is shown in the standard error.
Decrease the output verbosity. Each usage of this option will
decrease the verbosity (less than zero doesn’t make sense) from
the default of one.
Just show the program version and exit.
The exist status of the command will be zero, unless for some reason
the algorithm fatally failed (e.g. wrong node or instance data).
The algorithm is highly dependent on the number of nodes; its runtime
grows exponentially with this number, and as such is impractical for
really big clusters.
The algorithm doesn’t rebalance the cluster or try to get the optimal
fit; it just allocates in the best place for the current step, without
taking into consideration the impact on future placements.
If the variables HTOOLS_NODES and HTOOLS_INSTANCES are present in the
environment, they will override the default names for the nodes and
instances files. These will have of course no effect when the RAPI or
Luxi backends are used.
hbal(1), hscan(1), ganeti(7), gnt-instance(8), gnt-node(8)
Copyright (C) 2009 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.