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HBAL(1) Ganeti | Version @GANETI_VERSION@ |
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========================================= |
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|
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NAME |
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---- |
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|
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hbal \- Cluster balancer for Ganeti |
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|
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SYNOPSIS |
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-------- |
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|
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**hbal** {backend options...} [algorithm options...] [reporting options...] |
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|
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**hbal** --version |
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|
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|
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Backend options: |
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|
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{ **-m** *cluster* | **-L[** *path* **] [-X]** | **-t** *data-file* } |
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|
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Algorithm options: |
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|
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**[ --max-cpu *cpu-ratio* ]** |
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**[ --min-disk *disk-ratio* ]** |
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**[ -l *limit* ]** |
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**[ -e *score* ]** |
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**[ -g *delta* ]** **[ --min-gain-limit *threshold* ]** |
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**[ -O *name...* ]** |
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**[ --no-disk-moves ]** |
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**[ --no-instance-moves ]** |
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**[ -U *util-file* ]** |
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**[ --evac-mode ]** |
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**[ --select-instances *inst...* ]** |
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**[ --exclude-instances *inst...* ]** |
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|
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Reporting options: |
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|
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**[ -C[ *file* ] ]** |
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**[ -p[ *fields* ] ]** |
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**[ --print-instances ]** |
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**[ -o ]** |
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**[ -v... | -q ]** |
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|
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|
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DESCRIPTION |
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----------- |
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|
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hbal is a cluster balancer that looks at the current state of the |
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cluster (nodes with their total and free disk, memory, etc.) and |
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instance placement and computes a series of steps designed to bring |
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the cluster into a better state. |
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|
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The algorithm used is designed to be stable (i.e. it will give you the |
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same results when restarting it from the middle of the solution) and |
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reasonably fast. It is not, however, designed to be a perfect |
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algorithm--it is possible to make it go into a corner from which |
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it can find no improvement, because it looks only one "step" ahead. |
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|
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By default, the program will show the solution incrementally as it is |
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computed, in a somewhat cryptic format; for getting the actual Ganeti |
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command list, use the **-C** option. |
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|
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ALGORITHM |
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~~~~~~~~~ |
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|
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The program works in independent steps; at each step, we compute the |
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best instance move that lowers the cluster score. |
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|
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The possible move type for an instance are combinations of |
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failover/migrate and replace-disks such that we change one of the |
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instance nodes, and the other one remains (but possibly with changed |
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role, e.g. from primary it becomes secondary). The list is: |
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|
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- failover (f) |
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- replace secondary (r) |
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- replace primary, a composite move (f, r, f) |
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- failover and replace secondary, also composite (f, r) |
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- replace secondary and failover, also composite (r, f) |
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|
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We don't do the only remaining possibility of replacing both nodes |
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(r,f,r,f or the equivalent f,r,f,r) since these move needs an |
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exhaustive search over both candidate primary and secondary nodes, and |
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is O(n*n) in the number of nodes. Furthermore, it doesn't seems to |
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give better scores but will result in more disk replacements. |
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|
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PLACEMENT RESTRICTIONS |
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~~~~~~~~~~~~~~~~~~~~~~ |
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|
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At each step, we prevent an instance move if it would cause: |
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|
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- a node to go into N+1 failure state |
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- an instance to move onto an offline node (offline nodes are either |
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read from the cluster or declared with *-O*) |
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- an exclusion-tag based conflict (exclusion tags are read from the |
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cluster and/or defined via the *--exclusion-tags* option) |
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- a max vcpu/pcpu ratio to be exceeded (configured via *--max-cpu*) |
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- min disk free percentage to go below the configured limit |
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(configured via *--min-disk*) |
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|
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CLUSTER SCORING |
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~~~~~~~~~~~~~~~ |
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|
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As said before, the algorithm tries to minimise the cluster score at |
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each step. Currently this score is computed as a sum of the following |
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components: |
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|
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- standard deviation of the percent of free memory |
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- standard deviation of the percent of reserved memory |
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- standard deviation of the percent of free disk |
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- count of nodes failing N+1 check |
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- count of instances living (either as primary or secondary) on |
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offline nodes |
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- count of instances living (as primary) on offline nodes; this |
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differs from the above metric by helping failover of such instances |
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in 2-node clusters |
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- standard deviation of the ratio of virtual-to-physical cpus (for |
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primary instances of the node) |
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- standard deviation of the dynamic load on the nodes, for cpus, |
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memory, disk and network |
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|
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The free memory and free disk values help ensure that all nodes are |
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somewhat balanced in their resource usage. The reserved memory helps |
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to ensure that nodes are somewhat balanced in holding secondary |
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instances, and that no node keeps too much memory reserved for |
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N+1. And finally, the N+1 percentage helps guide the algorithm towards |
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eliminating N+1 failures, if possible. |
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|
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Except for the N+1 failures and offline instances counts, we use the |
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standard deviation since when used with values within a fixed range |
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(we use percents expressed as values between zero and one) it gives |
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consistent results across all metrics (there are some small issues |
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related to different means, but it works generally well). The 'count' |
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type values will have higher score and thus will matter more for |
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balancing; thus these are better for hard constraints (like evacuating |
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nodes and fixing N+1 failures). For example, the offline instances |
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count (i.e. the number of instances living on offline nodes) will |
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cause the algorithm to actively move instances away from offline |
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nodes. This, coupled with the restriction on placement given by |
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offline nodes, will cause evacuation of such nodes. |
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|
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The dynamic load values need to be read from an external file (Ganeti |
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doesn't supply them), and are computed for each node as: sum of |
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primary instance cpu load, sum of primary instance memory load, sum of |
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primary and secondary instance disk load (as DRBD generates write load |
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on secondary nodes too in normal case and in degraded scenarios also |
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read load), and sum of primary instance network load. An example of |
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how to generate these values for input to hbal would be to track ``xm |
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list`` for instances over a day and by computing the delta of the cpu |
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values, and feed that via the *-U* option for all instances (and keep |
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the other metrics as one). For the algorithm to work, all that is |
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needed is that the values are consistent for a metric across all |
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instances (e.g. all instances use cpu% to report cpu usage, and not |
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something related to number of CPU seconds used if the CPUs are |
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different), and that they are normalised to between zero and one. Note |
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that it's recommended to not have zero as the load value for any |
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instance metric since then secondary instances are not well balanced. |
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|
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On a perfectly balanced cluster (all nodes the same size, all |
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instances the same size and spread across the nodes equally), the |
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values for all metrics would be zero. This doesn't happen too often in |
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practice :) |
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|
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OFFLINE INSTANCES |
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~~~~~~~~~~~~~~~~~ |
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|
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Since current Ganeti versions do not report the memory used by offline |
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(down) instances, ignoring the run status of instances will cause |
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wrong calculations. For this reason, the algorithm subtracts the |
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memory size of down instances from the free node memory of their |
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primary node, in effect simulating the startup of such instances. |
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|
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EXCLUSION TAGS |
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~~~~~~~~~~~~~~ |
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|
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The exclusion tags mechanism is designed to prevent instances which |
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run the same workload (e.g. two DNS servers) to land on the same node, |
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which would make the respective node a SPOF for the given service. |
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|
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It works by tagging instances with certain tags and then building |
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exclusion maps based on these. Which tags are actually used is |
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configured either via the command line (option *--exclusion-tags*) |
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or via adding them to the cluster tags: |
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|
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--exclusion-tags=a,b |
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This will make all instance tags of the form *a:\**, *b:\** be |
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considered for the exclusion map |
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|
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cluster tags *htools:iextags:a*, *htools:iextags:b* |
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This will make instance tags *a:\**, *b:\** be considered for the |
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exclusion map. More precisely, the suffix of cluster tags starting |
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with *htools:iextags:* will become the prefix of the exclusion tags. |
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|
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Both the above forms mean that two instances both having (e.g.) the |
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tag *a:foo* or *b:bar* won't end on the same node. |
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|
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OPTIONS |
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------- |
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|
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The options that can be passed to the program are as follows: |
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|
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-C, --print-commands |
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Print the command list at the end of the run. Without this, the |
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program will only show a shorter, but cryptic output. |
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|
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Note that the moves list will be split into independent steps, |
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called "jobsets", but only for visual inspection, not for actually |
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parallelisation. It is not possible to parallelise these directly |
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when executed via "gnt-instance" commands, since a compound command |
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(e.g. failover and replace-disks) must be executed |
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serially. Parallel execution is only possible when using the Luxi |
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backend and the *-L* option. |
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|
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The algorithm for splitting the moves into jobsets is by |
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accumulating moves until the next move is touching nodes already |
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touched by the current moves; this means we can't execute in |
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parallel (due to resource allocation in Ganeti) and thus we start a |
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new jobset. |
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|
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-p, --print-nodes |
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Prints the before and after node status, in a format designed to allow |
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the user to understand the node's most important parameters. See the |
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man page **htools**(1) for more details about this option. |
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|
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--print-instances |
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Prints the before and after instance map. This is less useful as the |
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node status, but it can help in understanding instance moves. |
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|
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-O *name* |
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This option (which can be given multiple times) will mark nodes as |
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being *offline*. This means a couple of things: |
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|
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- instances won't be placed on these nodes, not even temporarily; |
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e.g. the *replace primary* move is not available if the secondary |
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node is offline, since this move requires a failover. |
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- these nodes will not be included in the score calculation (except |
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for the percentage of instances on offline nodes) |
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|
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Note that algorithm will also mark as offline any nodes which are |
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reported by RAPI as such, or that have "?" in file-based input in |
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any numeric fields. |
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|
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-e *score*, --min-score=*score* |
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This parameter denotes the minimum score we are happy with and alters |
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the computation in two ways: |
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|
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- if the cluster has the initial score lower than this value, then we |
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don't enter the algorithm at all, and exit with success |
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- during the iterative process, if we reach a score lower than this |
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value, we exit the algorithm |
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|
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The default value of the parameter is currently ``1e-9`` (chosen |
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empirically). |
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|
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-g *delta*, --min-gain=*delta* |
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Since the balancing algorithm can sometimes result in just very tiny |
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improvements, that bring less gain that they cost in relocation |
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time, this parameter (defaulting to 0.01) represents the minimum |
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gain we require during a step, to continue balancing. |
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|
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--min-gain-limit=*threshold* |
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The above min-gain option will only take effect if the cluster score |
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is already below *threshold* (defaults to 0.1). The rationale behind |
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this setting is that at high cluster scores (badly balanced |
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clusters), we don't want to abort the rebalance too quickly, as |
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later gains might still be significant. However, under the |
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threshold, the total gain is only the threshold value, so we can |
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exit early. |
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|
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--no-disk-moves |
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This parameter prevents hbal from using disk move |
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(i.e. "gnt-instance replace-disks") operations. This will result in |
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a much quicker balancing, but of course the improvements are |
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limited. It is up to the user to decide when to use one or another. |
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|
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--no-instance-moves |
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This parameter prevents hbal from using instance moves |
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(i.e. "gnt-instance migrate/failover") operations. This will only use |
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the slow disk-replacement operations, and will also provide a worse |
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balance, but can be useful if moving instances around is deemed unsafe |
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or not preferred. |
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|
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--evac-mode |
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This parameter restricts the list of instances considered for moving |
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to the ones living on offline/drained nodes. It can be used as a |
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(bulk) replacement for Ganeti's own *gnt-node evacuate*, with the |
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note that it doesn't guarantee full evacuation. |
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|
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--select-instances=*instances* |
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This parameter marks the given instances (as a comma-separated list) |
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as the only ones being moved during the rebalance. |
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|
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--exclude-instances=*instances* |
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This parameter marks the given instances (as a comma-separated list) |
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from being moved during the rebalance. |
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|
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-U *util-file* |
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This parameter specifies a file holding instance dynamic utilisation |
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information that will be used to tweak the balancing algorithm to |
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equalise load on the nodes (as opposed to static resource |
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usage). The file is in the format "instance_name cpu_util mem_util |
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disk_util net_util" where the "_util" parameters are interpreted as |
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numbers and the instance name must match exactly the instance as |
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read from Ganeti. In case of unknown instance names, the program |
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will abort. |
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|
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If not given, the default values are one for all metrics and thus |
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dynamic utilisation has only one effect on the algorithm: the |
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equalisation of the secondary instances across nodes (this is the |
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only metric that is not tracked by another, dedicated value, and |
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thus the disk load of instances will cause secondary instance |
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equalisation). Note that value of one will also influence slightly |
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the primary instance count, but that is already tracked via other |
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metrics and thus the influence of the dynamic utilisation will be |
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practically insignificant. |
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|
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-S *filename*, --save-cluster=*filename* |
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If given, the state of the cluster before the balancing is saved to |
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the given file plus the extension "original" |
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(i.e. *filename*.original), and the state at the end of the |
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balancing is saved to the given file plus the extension "balanced" |
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(i.e. *filename*.balanced). This allows re-feeding the cluster state |
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to either hbal itself or for example hspace via the ``-t`` option. |
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|
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-t *datafile*, --text-data=*datafile* |
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Backend specification: the name of the file holding node and instance |
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information (if not collecting via RAPI or LUXI). This or one of the |
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other backends must be selected. The option is described in the man |
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page **htools**(1). |
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|
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-m *cluster* |
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Backend specification: collect data directly from the *cluster* given |
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as an argument via RAPI. The option is described in the man page |
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**htools**(1). |
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|
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-L [*path*] |
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Backend specification: collect data directly from the master daemon, |
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which is to be contacted via LUXI (an internal Ganeti protocol). The |
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option is described in the man page **htools**(1). |
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|
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-X |
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When using the Luxi backend, hbal can also execute the given |
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commands. The execution method is to execute the individual jobsets |
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(see the *-C* option for details) in separate stages, aborting if at |
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any time a jobset doesn't have all jobs successful. Each step in the |
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balancing solution will be translated into exactly one Ganeti job |
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(having between one and three OpCodes), and all the steps in a |
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jobset will be executed in parallel. The jobsets themselves are |
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executed serially. |
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|
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The execution of the job series can be interrupted, see below for |
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signal handling. |
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|
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-l *N*, --max-length=*N* |
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Restrict the solution to this length. This can be used for example |
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to automate the execution of the balancing. |
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|
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--max-cpu=*cpu-ratio* |
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The maximum virtual to physical cpu ratio, as a floating point number |
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greater than or equal to one. For example, specifying *cpu-ratio* as |
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**2.5** means that, for a 4-cpu machine, a maximum of 10 virtual cpus |
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should be allowed to be in use for primary instances. A value of |
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exactly one means there will be no over-subscription of CPU (except |
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for the CPU time used by the node itself), and values below one do not |
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make sense, as that means other resources (e.g. disk) won't be fully |
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utilised due to CPU restrictions. |
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|
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--min-disk=*disk-ratio* |
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The minimum amount of free disk space remaining, as a floating point |
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number. For example, specifying *disk-ratio* as **0.25** means that |
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at least one quarter of disk space should be left free on nodes. |
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|
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-G *uuid*, --group=*uuid* |
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On an multi-group cluster, select this group for |
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processing. Otherwise hbal will abort, since it cannot balance |
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multiple groups at the same time. |
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|
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-v, --verbose |
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Increase the output verbosity. Each usage of this option will |
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increase the verbosity (currently more than 2 doesn't make sense) |
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from the default of one. |
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|
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-q, --quiet |
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Decrease the output verbosity. Each usage of this option will |
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decrease the verbosity (less than zero doesn't make sense) from the |
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default of one. |
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|
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-V, --version |
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Just show the program version and exit. |
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|
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SIGNAL HANDLING |
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--------------- |
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|
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When executing jobs via LUXI (using the ``-X`` option), normally hbal |
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will execute all jobs until either one errors out or all the jobs finish |
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successfully. |
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|
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Since balancing can take a long time, it is possible to stop hbal early |
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in two ways: |
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|
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- by sending a ``SIGINT`` (``^C``), hbal will register the termination |
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request, and will wait until the currently submitted jobs finish, at |
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which point it will exit (with exit code 1) |
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- by sending a ``SIGTERM``, hbal will immediately exit (with exit code |
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2); it is the responsibility of the user to follow up with Ganeti the |
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result of the currently-executing jobs |
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|
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Note that in any situation, it's perfectly safe to kill hbal, either via |
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the above signals or via any other signal (e.g. ``SIGQUIT``, |
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``SIGKILL``), since the jobs themselves are processed by Ganeti whereas |
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hbal (after submission) only watches their progression. In this case, |
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the use will again have to query Ganeti for job results. |
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|
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EXIT STATUS |
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----------- |
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|
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The exit status of the command will be zero, unless for some reason the |
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algorithm fatally failed (e.g. wrong node or instance data), or (in case |
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of job execution) either one of the jobs has failed or the balancing was |
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interrupted early. |
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|
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BUGS |
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---- |
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|
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The program does not check all its input data for consistency, and |
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sometime aborts with cryptic errors messages with invalid data. |
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|
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The algorithm is not perfect. |
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|
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EXAMPLE |
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------- |
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|
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Note that these examples are not for the latest version (they don't |
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have full node data). |
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|
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Default output |
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~~~~~~~~~~~~~~ |
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|
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With the default options, the program shows each individual step and |
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the improvements it brings in cluster score:: |
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|
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$ hbal |
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Loaded 20 nodes, 80 instances |
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Cluster is not N+1 happy, continuing but no guarantee that the cluster will end N+1 happy. |
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Initial score: 0.52329131 |
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Trying to minimize the CV... |
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1. instance14 node1:node10 => node16:node10 0.42109120 a=f r:node16 f |
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2. instance54 node4:node15 => node16:node15 0.31904594 a=f r:node16 f |
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3. instance4 node5:node2 => node2:node16 0.26611015 a=f r:node16 |
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4. instance48 node18:node20 => node2:node18 0.21361717 a=r:node2 f |
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5. instance93 node19:node18 => node16:node19 0.16166425 a=r:node16 f |
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6. instance89 node3:node20 => node2:node3 0.11005629 a=r:node2 f |
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7. instance5 node6:node2 => node16:node6 0.05841589 a=r:node16 f |
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8. instance94 node7:node20 => node20:node16 0.00658759 a=f r:node16 |
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9. instance44 node20:node2 => node2:node15 0.00438740 a=f r:node15 |
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10. instance62 node14:node18 => node14:node16 0.00390087 a=r:node16 |
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11. instance13 node11:node14 => node11:node16 0.00361787 a=r:node16 |
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12. instance19 node10:node11 => node10:node7 0.00336636 a=r:node7 |
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13. instance43 node12:node13 => node12:node1 0.00305681 a=r:node1 |
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14. instance1 node1:node2 => node1:node4 0.00263124 a=r:node4 |
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15. instance58 node19:node20 => node19:node17 0.00252594 a=r:node17 |
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Cluster score improved from 0.52329131 to 0.00252594 |
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|
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In the above output, we can see: |
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|
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- the input data (here from files) shows a cluster with 20 nodes and |
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80 instances |
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- the cluster is not initially N+1 compliant |
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- the initial score is 0.52329131 |
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|
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The step list follows, showing the instance, its initial |
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primary/secondary nodes, the new primary secondary, the cluster list, |
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and the actions taken in this step (with 'f' denoting failover/migrate |
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and 'r' denoting replace secondary). |
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|
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Finally, the program shows the improvement in cluster score. |
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|
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A more detailed output is obtained via the *-C* and *-p* options:: |
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|
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$ hbal |
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Loaded 20 nodes, 80 instances |
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Cluster is not N+1 happy, continuing but no guarantee that the cluster will end N+1 happy. |
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Initial cluster status: |
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N1 Name t_mem f_mem r_mem t_dsk f_dsk pri sec p_fmem p_fdsk |
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* node1 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
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node2 32762 31280 12000 1861 1026 0 8 0.95476 0.55179 |
486 |
* node3 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
487 |
* node4 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
488 |
* node5 32762 1280 6000 1861 978 5 5 0.03907 0.52573 |
489 |
* node6 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
490 |
* node7 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
491 |
node8 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
492 |
node9 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
493 |
* node10 32762 7280 12000 1861 1026 4 4 0.22221 0.55179 |
494 |
node11 32762 7280 6000 1861 922 4 5 0.22221 0.49577 |
495 |
node12 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
496 |
node13 32762 7280 6000 1861 922 4 5 0.22221 0.49577 |
497 |
node14 32762 7280 6000 1861 922 4 5 0.22221 0.49577 |
498 |
* node15 32762 7280 12000 1861 1131 4 3 0.22221 0.60782 |
499 |
node16 32762 31280 0 1861 1860 0 0 0.95476 1.00000 |
500 |
node17 32762 7280 6000 1861 1106 5 3 0.22221 0.59479 |
501 |
* node18 32762 1280 6000 1396 561 5 3 0.03907 0.40239 |
502 |
* node19 32762 1280 6000 1861 1026 5 3 0.03907 0.55179 |
503 |
node20 32762 13280 12000 1861 689 3 9 0.40535 0.37068 |
504 |
|
505 |
Initial score: 0.52329131 |
506 |
Trying to minimize the CV... |
507 |
1. instance14 node1:node10 => node16:node10 0.42109120 a=f r:node16 f |
508 |
2. instance54 node4:node15 => node16:node15 0.31904594 a=f r:node16 f |
509 |
3. instance4 node5:node2 => node2:node16 0.26611015 a=f r:node16 |
510 |
4. instance48 node18:node20 => node2:node18 0.21361717 a=r:node2 f |
511 |
5. instance93 node19:node18 => node16:node19 0.16166425 a=r:node16 f |
512 |
6. instance89 node3:node20 => node2:node3 0.11005629 a=r:node2 f |
513 |
7. instance5 node6:node2 => node16:node6 0.05841589 a=r:node16 f |
514 |
8. instance94 node7:node20 => node20:node16 0.00658759 a=f r:node16 |
515 |
9. instance44 node20:node2 => node2:node15 0.00438740 a=f r:node15 |
516 |
10. instance62 node14:node18 => node14:node16 0.00390087 a=r:node16 |
517 |
11. instance13 node11:node14 => node11:node16 0.00361787 a=r:node16 |
518 |
12. instance19 node10:node11 => node10:node7 0.00336636 a=r:node7 |
519 |
13. instance43 node12:node13 => node12:node1 0.00305681 a=r:node1 |
520 |
14. instance1 node1:node2 => node1:node4 0.00263124 a=r:node4 |
521 |
15. instance58 node19:node20 => node19:node17 0.00252594 a=r:node17 |
522 |
Cluster score improved from 0.52329131 to 0.00252594 |
523 |
|
524 |
Commands to run to reach the above solution: |
525 |
echo step 1 |
526 |
echo gnt-instance migrate instance14 |
527 |
echo gnt-instance replace-disks -n node16 instance14 |
528 |
echo gnt-instance migrate instance14 |
529 |
echo step 2 |
530 |
echo gnt-instance migrate instance54 |
531 |
echo gnt-instance replace-disks -n node16 instance54 |
532 |
echo gnt-instance migrate instance54 |
533 |
echo step 3 |
534 |
echo gnt-instance migrate instance4 |
535 |
echo gnt-instance replace-disks -n node16 instance4 |
536 |
echo step 4 |
537 |
echo gnt-instance replace-disks -n node2 instance48 |
538 |
echo gnt-instance migrate instance48 |
539 |
echo step 5 |
540 |
echo gnt-instance replace-disks -n node16 instance93 |
541 |
echo gnt-instance migrate instance93 |
542 |
echo step 6 |
543 |
echo gnt-instance replace-disks -n node2 instance89 |
544 |
echo gnt-instance migrate instance89 |
545 |
echo step 7 |
546 |
echo gnt-instance replace-disks -n node16 instance5 |
547 |
echo gnt-instance migrate instance5 |
548 |
echo step 8 |
549 |
echo gnt-instance migrate instance94 |
550 |
echo gnt-instance replace-disks -n node16 instance94 |
551 |
echo step 9 |
552 |
echo gnt-instance migrate instance44 |
553 |
echo gnt-instance replace-disks -n node15 instance44 |
554 |
echo step 10 |
555 |
echo gnt-instance replace-disks -n node16 instance62 |
556 |
echo step 11 |
557 |
echo gnt-instance replace-disks -n node16 instance13 |
558 |
echo step 12 |
559 |
echo gnt-instance replace-disks -n node7 instance19 |
560 |
echo step 13 |
561 |
echo gnt-instance replace-disks -n node1 instance43 |
562 |
echo step 14 |
563 |
echo gnt-instance replace-disks -n node4 instance1 |
564 |
echo step 15 |
565 |
echo gnt-instance replace-disks -n node17 instance58 |
566 |
|
567 |
Final cluster status: |
568 |
N1 Name t_mem f_mem r_mem t_dsk f_dsk pri sec p_fmem p_fdsk |
569 |
node1 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
570 |
node2 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
571 |
node3 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
572 |
node4 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
573 |
node5 32762 7280 6000 1861 1078 4 5 0.22221 0.57947 |
574 |
node6 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
575 |
node7 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
576 |
node8 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
577 |
node9 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
578 |
node10 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
579 |
node11 32762 7280 6000 1861 1022 4 4 0.22221 0.54951 |
580 |
node12 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
581 |
node13 32762 7280 6000 1861 1022 4 4 0.22221 0.54951 |
582 |
node14 32762 7280 6000 1861 1022 4 4 0.22221 0.54951 |
583 |
node15 32762 7280 6000 1861 1031 4 4 0.22221 0.55408 |
584 |
node16 32762 7280 6000 1861 1060 4 4 0.22221 0.57007 |
585 |
node17 32762 7280 6000 1861 1006 5 4 0.22221 0.54105 |
586 |
node18 32762 7280 6000 1396 761 4 2 0.22221 0.54570 |
587 |
node19 32762 7280 6000 1861 1026 4 4 0.22221 0.55179 |
588 |
node20 32762 13280 6000 1861 1089 3 5 0.40535 0.58565 |
589 |
|
590 |
Here we see, beside the step list, the initial and final cluster |
591 |
status, with the final one showing all nodes being N+1 compliant, and |
592 |
the command list to reach the final solution. In the initial listing, |
593 |
we see which nodes are not N+1 compliant. |
594 |
|
595 |
The algorithm is stable as long as each step above is fully completed, |
596 |
e.g. in step 8, both the migrate and the replace-disks are |
597 |
done. Otherwise, if only the migrate is done, the input data is |
598 |
changed in a way that the program will output a different solution |
599 |
list (but hopefully will end in the same state). |
600 |
|
601 |
.. vim: set textwidth=72 : |
602 |
.. Local Variables: |
603 |
.. mode: rst |
604 |
.. fill-column: 72 |
605 |
.. End: |