Revision 5b53ca79
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DESCRIPTION |
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----------- |
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hail is a Ganeti IAllocator plugin that allows automatic instance |
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placement and automatic instance secondary node replacement using the |
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same algorithm as **hbal**(1). |
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hail is a Ganeti IAllocator plugin that implements the instance |
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placement and movement using the same algorithm as **hbal**(1). |
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The program takes input via a JSON-file containing current cluster |
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state and the request details, and output (on stdout) a JSON-formatted |
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The program uses a simplified version of the hbal algorithm. |
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For relocations, we try to change the secondary node of the instance |
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to all the valid other nodes; the node which results in the best |
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cluster score is chosen. |
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For single-node allocations (non-mirrored instances), again we |
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select the node which, when chosen as the primary node, gives the best |
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score. |
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pair; this is the only choice where the algorithm is non-trivial |
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with regard to cluster size. |
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For node evacuations (*multi-evacuate* mode), we iterate over all |
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instances which live as secondaries on those nodes and try to relocate |
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them using the single-instance relocation algorithm. |
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For node changes (*change-node* mode), we currently support DRBD |
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instances only, and all three modes (primary changes, secondary changes |
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and all node changes). |
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For group moves (*change-group* mode), again only DRBD is supported, and |
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we compute the correct sequence that will result in a group change; job |
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failure mid-way will result in a split instance. The choice of node(s) |
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on the target group is based on the group score, and the choice of group |
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is based on the same algorithm as allocations (group with lowest score |
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after placement). |
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The deprecated *relocate* and *multi-evacuate* modes are no longer |
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supported. |
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In all cases, the cluster scoring is identical to the hbal algorithm. |
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In all cases, the cluster (or group) scoring is identical to the hbal |
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algorithm. |
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OPTIONS |
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