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considered a fully-specified URL and is used as-is.

.TH HSPACE 1 2009-06-01 htools "Ganeti H-tools"

.SH NAME

hspace \- Cluster space analyzer for Ganeti

.SH SYNOPSIS

.B hspace

.B "[-p]"

.B "[-v... | -q]"

.BI "[-O" name... "]"

.BI "[-m " cluster "]"

.BI "[-n " nodes-file " ]"

.BI "[-i " instances-file "]"

.BI "[--memory " mem "]"

.BI "[--disk " disk "]"

.BI "[--req-nodes " req-nodes "]"

.B hspace

.B --version

.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.

With default options, the output of the program is designed to be

parseable; when the -p option is passed, this is no longer true.

.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

.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 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

.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

.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 program output.

.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 EXAMPLE

.SS Default output

.in +4n

.nf

.RB "$" " hspace --mem 16 --disk 16 --req-nodes 2"

Initial score: 0.38988095

Initial instances: 3

Initial free RAM: 546

Initial free disk: 260600

Final score: 0.32638889

Final instances: 7

Final free RAM: 482

Final free disk: 260472

Usage: 0.43

Allocations: 4

.fi

.in

This shows that (on this fake cluster), starting from 3 initial

instances, using the hail iallocator plugin, it would be possible to

add four (Allocations: 4) new instances to the cluster.

.SS Verbose output

For the same cluster as above:

.in +4n

.nf

.RB "$" " hspace --mem 16 --disk 16 --req-nodes 2 -v"

Initial score: 0.38988095

Initial instances: 3

Initial free RAM: 546

Initial free disk: 260600

Final score: 0.32638889

Final instances: 7

Final free RAM: 482

Final free disk: 260472

Usage: 0.43

Allocations: 4

Inst: new-0 node2 node1

Inst: new-1 node2 node1

Inst: new-2 node2 node1

Inst: new-3 node2 node1

.fi

.in

The output now includes the placement for the new instances (named

\fBnew-\fInumber\fR).

.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.