Document the --vcpus option to hspace

[ganeti-local] / hspace.1

.TH HSPACE 1 2009-06-01 htools "Ganeti H-tools"
.SH NAME
hspace \- Cluster space analyzer for Ganeti

.SH SYNOPSIS
.B hspace
.B "[backend options...]"
.B "[algorithm options...]"
.B "[request options..."]
.B "[-p]"
.B "[-v... | -q]"

.B hspace
.B --version

.TP
Backend options:
.BI "[ -m " cluster " ]"
|
.BI "[ -L[" path "]]"
|
.BI "[ -n " nodes-file " ]"
.BI "[ -i " instances-file " ]"

.TP
Algorithm options:
.BI "[ --max-cpu " cpu-ratio " ]"
.BI "[ --min-disk " disk-ratio " ]"
.BI "[ -O " name... " ]"

.TP
Request options:
.BI "[--memory " mem "]"
.BI "[--disk " disk "]"
.BI "[--req-nodes " req-nodes "]"
.BI "[--vcpus " vcpus "]"


.SH DESCRIPTION
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
iallocator plugin.

The output of the program is designed to interpreted as a shell
fragment (or parsed as a \fIkey=value\fR 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 \fIHTS_\fR):
.TP
.I 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).

.TP
.I CLUSTER_MEM, CLUSTER_DSK, CLUSTER_CPU, CLUSTER_NODES
These represent the total memory, disk, CPU count and total nodes in
the cluster.

.TP
.I INI_SCORE, FIN_SCORE
These are the initial (current) and final cluster score (see the hbal
man page for details about the scoring algorithm).

.TP
.I INI_INST_CNT, FIN_INST_CNT
The initial and final instance count.

.TP
.I INI_MEM_FREE, FIN_MEM_FREE
The initial and final total free memory in the cluster (but this
doesn't necessarily mean available for use).

.TP
.I INI_MEM_AVAIL, FIN_MEM_AVAIL
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 allocations.

.TP
.I INI_MEM_RESVD, FIN_MEM_RESVD
The initial and final reserved memory (for redundancy/N+1 purposes).

.TP
.I INI_MEM_INST, FIN_MEM_INST
The initial and final memory used for instances (actual runtime used
RAM).

.TP
.I INI_MEM_OVERHEAD, FIN_MEM_OVERHEAD
The initial and final memory overhead - memory used for the node
itself and unacounted memory (e.g. due to hypervisor overhead).

.TP
.I INI_MEM_EFF, HTS_INI_MEM_EFF
The initial and final memory efficiency, represented as instance
memory divided by total memory.

.TP
.I INI_DSK_FREE, INI_DSK_AVAIL, INI_DSK_RESVD, INI_DSK_INST, INI_DSK_EFF
Initial disk stats, similar to the memory ones.

.TP
.I FIN_DSK_FREE, FIN_DSK_AVAIL, FIN_DSK_RESVD, FIN_DSK_INST, FIN_DSK_EFF
Final disk stats, similar to the memory ones.

.TP
.I INI_CPU_INST, FIN_CPU_INST
Initial and final number of virtual CPUs used by instances.

.TP
.I INI_CPU_EFF, FIN_CPU_EFF
The initial and final CPU efficiency, represented as the count of
virtual instance CPUs divided by the total physical CPU count.

.TP
.I INI_MNODE_MEM_AVAIL, FIN_MNODE_MEM_AVAIL
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.

.TP
.I INI_MNODE_DSK_AVAIL, FIN_MNODE_DSK_AVAIL
Like the above but for disk.

.TP
.I ALLOC_USAGE
The current usage represented as initial number of instances divided
per final number of instances.

.TP
.I ALLOC_COUNT
The number of instances allocated (delta between FIN_INST_CNT and
INI_INST_CNT).

.TP
.I ALLOC_FAIL*_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 all.

.TP
.I ALLOC_FAIL_REASON
The reason for most of the failures, being one of the above FAIL*
strings.

.TP
.I 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.

.SH OPTIONS
The options that can be passed to the program are as follows:

.TP
.BI "--memory " mem
The memory size of the instances to be placed (defaults to 4GiB).

.TP
.BI "--disk " disk
The disk size of the instances to be placed (defaults to 100GiB).

.TP
.BI "--req-nodes " num-nodes
The number of nodes for the instances; the default of two means
mirrored instances, while passing one means plain type instances.

.TP
.BI "--vcpus " vcpus
The number of VCPUs of the instances to be placed (defaults to 1).

.TP
.BI "--max-cpu " cpu-ratio
The maximum virtual-to-physical cpu ratio, as a floating point number
between zero and one. For example, specifying \fIcpu-ratio\fR as
\fB2.5\fR 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.

.TP
.BI "--min-disk " disk-ratio
The minimum amount of free disk space remaining, as a floating point
number. For example, specifying \fIdisk-ratio\fR as \fB0.25\fR means
that at least one quarter of disk space should be left free on nodes.

.TP
.B -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.

The node list will contain these informations:
.RS
.TP
.B F
a character denoting the status of the node, with '-' meaning an
offline node, '*' meaning N+1 failure and blank meaning a good node
.TP
.B Name
the node name
.TP
.B t_mem
the total node memory
.TP
.B n_mem
the memory used by the node itself
.TP
.B i_mem
the memory used by instances
.TP
.B 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
.TP
.B f_mem
the free node memory
.TP
.B r_mem
the reserved node memory, which is the amount of free memory needed
for N+1 compliance
.TP
.B t_dsk
total disk
.TP
.B f_dsk
free disk
.TP
.B pcpu
the number of physical cpus on the node
.TP
.B vcpu
the number of virtual cpus allocated to primary instances
.TP
.B pri
number of primary instances
.TP
.B sec
number of secondary instances
.TP
.B p_fmem
percent of free memory
.TP
.B p_fdsk
percent of free disk
.TP
.B r_cpu
ratio of virtual to physical cpus
.RE

.TP
.BI "-O " name
This option (which can be given multiple times) will mark nodes as
being \fIoffline\fR, 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.
.RE

.TP
.BI "-n" nodefile ", --nodes=" nodefile
The name of the file holding node information (if not collecting via
RAPI), instead of the default \fInodes\fR file (but see below how to
customize the default value via the environment).

.TP
.BI "-i" instancefile ", --instances=" instancefile
The name of the file holding instance information (if not collecting
via RAPI), instead of the default \fIinstances\fR file (but see below
how to customize the default value via the environment).

.TP
.BI "-m" cluster
Collect data not from files but directly from the
.I 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.

.TP
.BI "-L[" path "]"
Collect data not from files but directly from the master daemon, which
is to be contacted via the luxi (an internal Ganeti protocol). An
optional \fIpath\fR 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.

.TP
.B -v, --verbose
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.

.TP
.B -q, --quiet
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.

.TP
.B -V, --version
Just show the program version and exit.

.SH 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).

.SH BUGS

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.

.SH ENVIRONMENT

If the variables \fBHTOOLS_NODES\fR and \fBHTOOLS_INSTANCES\fR 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 RAPI is used.

.SH SEE ALSO
.BR hbal "(1), " hscan "(1), " ganeti "(7), " gnt-instance "(8), "
.BR gnt-node "(8)"

.SH "COPYRIGHT"
.PP
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.
.PP
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL.