1 HSPACE(1) Ganeti | Version @GANETI_VERSION@
2 ===========================================
7 hspace - Cluster space analyzer for Ganeti
12 **hspace** {backend options...} [algorithm options...] [request options...]
13 [output options...] [-v... | -q]
19 { **-m** *cluster* | **-L[** *path* **] [-X]** | **-t** *data-file* |
20 **--simulate** *spec* }
25 **[ --max-cpu *cpu-ratio* ]**
26 **[ --min-disk *disk-ratio* ]**
32 **[--memory** *mem* **]**
33 **[--disk** *disk* **]**
34 **[--disk-template** *template* **]**
35 **[--vcpus** *vcpus* **]**
36 **[--tiered-alloc** *spec* **]**
40 **[--machine-readable**[=*CHOICE*] **]**
41 **[-p**[*fields*]**]**
48 hspace computes how many additional instances can be fit on a cluster,
49 while maintaining N+1 status.
51 The program will try to place instances, all of the same size, on the
52 cluster, until the point where we don't have any N+1 possible
53 allocation. It uses the exact same allocation algorithm as the hail
54 iallocator plugin in *allocate* mode.
56 The output of the program is designed either for human consumption (the
57 default) or, when enabled with the ``--machine-readable`` option
58 (described further below), for machine consumption. In the latter case,
59 it is intended to interpreted as a shell fragment (or parsed as a
60 *key=value* file). Options which extend the output (e.g. -p, -v) will
61 output the additional information on stderr (such that the stdout is
64 The following keys are available in the machine-readable output of the
65 script (all prefixed with *HTS_*):
67 SPEC_MEM, SPEC_DSK, SPEC_CPU, SPEC_RQN, SPEC_DISK_TEMPLATE
68 These represent the specifications of the instance model used for
69 allocation (the memory, disk, cpu, requested nodes, disk template).
71 TSPEC_INI_MEM, TSPEC_INI_DSK, TSPEC_INI_CPU, ...
72 Only defined when the tiered mode allocation is enabled, these are
73 similar to the above specifications but show the initial starting spec
74 for tiered allocation.
76 CLUSTER_MEM, CLUSTER_DSK, CLUSTER_CPU, CLUSTER_NODES
77 These represent the total memory, disk, CPU count and total nodes in
81 These are the initial (current) and final cluster score (see the hbal
82 man page for details about the scoring algorithm).
84 INI_INST_CNT, FIN_INST_CNT
85 The initial and final instance count.
87 INI_MEM_FREE, FIN_MEM_FREE
88 The initial and final total free memory in the cluster (but this
89 doesn't necessarily mean available for use).
91 INI_MEM_AVAIL, FIN_MEM_AVAIL
92 The initial and final total available memory for allocation in the
93 cluster. If allocating redundant instances, new instances could
94 increase the reserved memory so it doesn't necessarily mean the
95 entirety of this memory can be used for new instance allocations.
97 INI_MEM_RESVD, FIN_MEM_RESVD
98 The initial and final reserved memory (for redundancy/N+1 purposes).
100 INI_MEM_INST, FIN_MEM_INST
101 The initial and final memory used for instances (actual runtime used
104 INI_MEM_OVERHEAD, FIN_MEM_OVERHEAD
105 The initial and final memory overhead--memory used for the node
106 itself and unacounted memory (e.g. due to hypervisor overhead).
108 INI_MEM_EFF, HTS_INI_MEM_EFF
109 The initial and final memory efficiency, represented as instance
110 memory divided by total memory.
112 INI_DSK_FREE, INI_DSK_AVAIL, INI_DSK_RESVD, INI_DSK_INST, INI_DSK_EFF
113 Initial disk stats, similar to the memory ones.
115 FIN_DSK_FREE, FIN_DSK_AVAIL, FIN_DSK_RESVD, FIN_DSK_INST, FIN_DSK_EFF
116 Final disk stats, similar to the memory ones.
118 INI_CPU_INST, FIN_CPU_INST
119 Initial and final number of virtual CPUs used by instances.
121 INI_CPU_EFF, FIN_CPU_EFF
122 The initial and final CPU efficiency, represented as the count of
123 virtual instance CPUs divided by the total physical CPU count.
125 INI_MNODE_MEM_AVAIL, FIN_MNODE_MEM_AVAIL
126 The initial and final maximum per-node available memory. This is not
127 very useful as a metric but can give an impression of the status of
128 the nodes; as an example, this value restricts the maximum instance
129 size that can be still created on the cluster.
131 INI_MNODE_DSK_AVAIL, FIN_MNODE_DSK_AVAIL
132 Like the above but for disk.
135 If the tiered allocation mode has been enabled, this parameter holds
136 the pairs of specifications and counts of instances that can be
137 created in this mode. The value of the key is a space-separated list
138 of values; each value is of the form *memory,disk,vcpu=count* where
139 the memory, disk and vcpu are the values for the current spec, and
140 count is how many instances of this spec can be created. A complete
141 value for this variable could be: **4096,102400,2=225
142 2560,102400,2=20 512,102400,2=21**.
144 KM_USED_CPU, KM_USED_NPU, KM_USED_MEM, KM_USED_DSK
145 These represents the metrics of used resources at the start of the
146 computation (only for tiered allocation mode). The NPU value is
147 "normalized" CPU count, i.e. the number of virtual CPUs divided by
148 the maximum ratio of the virtual to physical CPUs.
150 KM_POOL_CPU, KM_POOL_NPU, KM_POOL_MEM, KM_POOL_DSK
151 These represents the total resources allocated during the tiered
152 allocation process. In effect, they represent how much is readily
153 available for allocation.
155 KM_UNAV_CPU, KM_POOL_NPU, KM_UNAV_MEM, KM_UNAV_DSK
156 These represents the resources left over (either free as in
157 unallocable or allocable on their own) after the tiered allocation
158 has been completed. They represent better the actual unallocable
159 resources, because some other resource has been exhausted. For
160 example, the cluster might still have 100GiB disk free, but with no
161 memory left for instances, we cannot allocate another instance, so
162 in effect the disk space is unallocable. Note that the CPUs here
163 represent instance virtual CPUs, and in case the *--max-cpu* option
164 hasn't been specified this will be -1.
167 The current usage represented as initial number of instances divided
168 per final number of instances.
171 The number of instances allocated (delta between FIN_INST_CNT and
175 For the last attemp at allocations (which would have increased
176 FIN_INST_CNT with one, if it had succeeded), this is the count of
177 the failure reasons per failure type; currently defined are FAILMEM,
178 FAILDISK and FAILCPU which represent errors due to not enough
179 memory, disk and CPUs, and FAILN1 which represents a non N+1
180 compliant cluster on which we can't allocate instances at all.
183 The reason for most of the failures, being one of the above FAIL*
187 A marker representing the successful end of the computation, and
188 having value "1". If this key is not present in the output it means
189 that the computation failed and any values present should not be
192 If the tiered allocation mode is enabled, then many of the INI_/FIN_
193 metrics will be also displayed with a TRL_ prefix, and denote the
194 cluster status at the end of the tiered allocation run.
196 The human output format should be self-explanatory, so it is not
202 The options that can be passed to the program are as follows:
205 The memory size of the instances to be placed (defaults to
206 4GiB). Units can be used (see below for more details).
209 The disk size of the instances to be placed (defaults to
210 100GiB). Units can be used.
212 --disk-template *template*
213 The disk template for the instance; one of the Ganeti disk templates
214 (e.g. plain, drbd, so on) should be passed in.
217 The number of VCPUs of the instances to be placed (defaults to 1).
219 --max-cpu=*cpu-ratio*
220 The maximum virtual to physical cpu ratio, as a floating point number
221 greater than or equal to one. For example, specifying *cpu-ratio* as
222 **2.5** means that, for a 4-cpu machine, a maximum of 10 virtual cpus
223 should be allowed to be in use for primary instances. A value of
224 exactly one means there will be no over-subscription of CPU (except
225 for the CPU time used by the node itself), and values below one do not
226 make sense, as that means other resources (e.g. disk) won't be fully
227 utilised due to CPU restrictions.
229 --min-disk=*disk-ratio*
230 The minimum amount of free disk space remaining, as a floating point
231 number. For example, specifying *disk-ratio* as **0.25** means that
232 at least one quarter of disk space should be left free on nodes.
235 Prints the before and after node status, in a format designed to allow
236 the user to understand the node's most important parameters. See the
237 man page **htools**(1) for more details about this option.
240 This option (which can be given multiple times) will mark nodes as
241 being *offline*. This means a couple of things:
243 - instances won't be placed on these nodes, not even temporarily;
244 e.g. the *replace primary* move is not available if the secondary
245 node is offline, since this move requires a failover.
246 - these nodes will not be included in the score calculation (except
247 for the percentage of instances on offline nodes)
249 Note that the algorithm will also mark as offline any nodes which
250 are reported by RAPI as such, or that have "?" in file-based input
251 in any numeric fields.
253 -t *datafile*, --text-data=*datafile*
254 The name of the file holding node and instance information (if not
255 collecting via RAPI or LUXI). This or one of the other backends must
258 -S *filename*, --save-cluster=*filename*
259 If given, the state of the cluster at the end of the allocation is
260 saved to a file named *filename.alloc*, and if tiered allocation is
261 enabled, the state after tiered allocation will be saved to
262 *filename.tiered*. This allows re-feeding the cluster state to
263 either hspace itself (with different parameters) or for example
267 Collect data directly from the *cluster* given as an argument via
268 RAPI. If the argument doesn't contain a colon (:), then it is
269 converted into a fully-built URL via prepending ``https://`` and
270 appending the default RAPI port, otherwise it's considered a
271 fully-specified URL and is used as-is.
274 Collect data directly from the master daemon, which is to be
275 contacted via the luxi (an internal Ganeti protocol). An optional
276 *path* argument is interpreted as the path to the unix socket on
277 which the master daemon listens; otherwise, the default path used by
278 ganeti when installed with *--localstatedir=/var* is used.
280 --simulate *description*
281 Instead of using actual data, build an empty cluster given a node
282 description. The *description* parameter must be a comma-separated
283 list of five elements, describing in order:
285 - the allocation policy for this node group
286 - the number of nodes in the cluster
287 - the disk size of the nodes (default in mebibytes, units can be used)
288 - the memory size of the nodes (default in mebibytes, units can be used)
289 - the cpu core count for the nodes
291 An example description would be **preferred,B20,100G,16g,4**
292 describing a 20-node cluster where each node has 100GB of disk
293 space, 16GiB of memory and 4 CPU cores. Note that all nodes must
294 have the same specs currently.
296 This option can be given multiple times, and each new use defines a
297 new node group. Hence different node groups can have different
298 allocation policies and node count/specifications.
300 --tiered-alloc *spec*
301 Besides the standard, fixed-size allocation, also do a tiered
302 allocation scheme where the algorithm starts from the given
303 specification and allocates until there is no more space; then it
304 decreases the specification and tries the allocation again. The
305 decrease is done on the matric that last failed during
306 allocation. The specification given is similar to the *--simulate*
309 - the disk size of the instance (units can be used)
310 - the memory size of the instance (units can be used)
311 - the vcpu count for the insance
313 An example description would be *100G,4g,2* describing an initial
314 starting specification of 100GB of disk space, 4GiB of memory and 2
317 Also note that the normal allocation and the tiered allocation are
318 independent, and both start from the initial cluster state; as such,
319 the instance count for these two modes are not related one to
322 --machines-readable[=*choice*]
323 By default, the output of the program is in "human-readable" format,
324 i.e. text descriptions. By passing this flag you can either enable
325 (``--machine-readable`` or ``--machine-readable=yes``) or explicitly
326 disable (``--machine-readable=no``) the machine readable format
330 Increase the output verbosity. Each usage of this option will
331 increase the verbosity (currently more than 2 doesn't make sense)
332 from the default of one.
335 Decrease the output verbosity. Each usage of this option will
336 decrease the verbosity (less than zero doesn't make sense) from the
340 Just show the program version and exit.
345 By default, all unit-accepting options use mebibytes. Using the
346 lower-case letters of *m*, *g* and *t* (or their longer equivalents of
347 *mib*, *gib*, *tib*, for which case doesn't matter) explicit binary
348 units can be selected. Units in the SI system can be selected using the
349 upper-case letters of *M*, *G* and *T* (or their longer equivalents of
350 *MB*, *GB*, *TB*, for which case doesn't matter).
352 More details about the difference between the SI and binary systems can
353 be read in the *units(7)* man page.
358 The exist status of the command will be zero, unless for some reason
359 the algorithm fatally failed (e.g. wrong node or instance data).
364 The algorithm is highly dependent on the number of nodes; its runtime
365 grows exponentially with this number, and as such is impractical for
368 The algorithm doesn't rebalance the cluster or try to get the optimal
369 fit; it just allocates in the best place for the current step, without
370 taking into consideration the impact on future placements.
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