Revision d1f5d461 hbal.1
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.BI "[ -e " score " ]" |
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.BI "[ -O " name... " ]" |
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.B "[ --no-disk-moves ]" |
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.BI "[ -U " util-file " ]" |
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.TP |
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Reporting options: |
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\(em |
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coefficent of variance of the ratio of virtual-to-physical cpus (for |
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primary instaces of the node) |
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.TP |
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\(em |
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coefficients of variance of the dynamic load on the nodes, for cpus, |
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memory, disk and network |
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.RE |
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The free memory and free disk values help ensure that all nodes are |
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on placement given by offline nodes, will cause evacuation of such |
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nodes. |
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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 instance over a day and by computing the delta of the cpu |
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values, and feed that via the \fI-U\fR option for all instances (and |
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keep the other metrics as zero). For the algorithm to work, all that |
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is 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, but they |
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could represent network bandwith in Gbps). |
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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), all |
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values would be zero. This doesn't happen too often in practice :) |
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.TP |
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.BI "--no-disk-moves" |
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This parameter prevent hbal from using disk move (i.e. "gnt-instance |
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This parameter prevents hbal from using disk move (i.e. "gnt-instance
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replace-disks") operations. This will result in a much quicker |
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balancing, but of course the improvements are limited. It is up to the |
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user to decide when to use one or another. |
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.TP |
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.BI "-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 usage). The |
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file is in the format "instance_name cpu_util mem_util disk_util |
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net_util" where the "_util" parameters are interpreted as numbers and |
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the instance name must match exactly the instance as read from |
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Ganeti. In case of unknown instance names, the program will abort. |
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If not given, the default values are zero for all metrics and thus |
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dynamic utilisation has no effect on the balancing algorithm. |
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.TP |
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.BI "-n" nodefile ", --nodes=" nodefile |
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The name of the file holding node information (if not collecting via |
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RAPI), instead of the default \fInodes\fR file (but see below how to |
Also available in: Unified diff