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HROLLER(1) Ganeti | Version @GANETI_VERSION@ |
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============================================ |
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NAME |
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---- |
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hroller \- Cluster rolling maintenance scheduler for Ganeti |
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SYNOPSIS |
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-------- |
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**hroller** {backend options...} [algorithm options...] [reporting options...]
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**hroller** \--version |
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Backend options: |
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{ **-m** *cluster* | **-L[** *path* **]** | **-t** *data-file* |
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**-I** *path* } |
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**[ --force ]** |
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Algorithm options: |
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**[ -G *name* ]** |
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**[ -O *name...* ]** |
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**[ --node-tags** *tag,..* **]** |
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Reporting options: |
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**[ -v... | -q ]** |
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**[ -S *file* ]** |
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**[ --one-step-only ]** |
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DESCRIPTION |
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----------- |
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hroller is a cluster maintenance reboot scheduler. It can calculate |
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which set of nodes can be rebooted at the same time while avoiding |
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having both primary and secondary nodes being rebooted at the same time. |
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For backends that support identifying the master node (currenlty |
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RAPI and LUXI), the master node is scheduled as the last node |
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in the last reboot group. Apart from this restriction, larger reboot |
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groups are put first. |
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ALGORITHM FOR CALCULATING OFFLINE REBOOT GROUPS |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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hroller will view the nodes as vertices of an undirected graph, |
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connecting by instances which have both a primary and a secondary node. |
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It will then color the graph using a few different heuristics, and |
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return the minimum-size color set found. Node with the same color don't |
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share an edge, and as such don't have an instance with both primary and |
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secondary node on them, so they are safe to be rebooted concurrently. |
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OPTIONS |
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------- |
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For a description of the standard options check **htools**\(7) and |
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**hbal**\(1). |
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\--node-tags *tag,...* |
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Restrict to nodes having at least one of the given tags. |
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\--one-step-only |
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Restrict to the first reboot group. Output the group one node per line. |
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\--force |
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Do not fail, even if the master node cannot be determined. |
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BUGS |
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---- |
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Offline nodes should be ignored. |
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If instances are online the tool should refuse to do offline rolling |
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maintenances, unless explicitly requested. |
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End-to-end shelltests should be provided. |
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Online rolling maintenances (where instance need not be shut down, but |
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are migrated from node to node) are not supported yet. Hroller by design |
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should support them both with and without secondary node replacement. |
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EXAMPLE |
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------- |
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Offline Rolling node reboot output |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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With the default options, the program shows one reboot group per line as |
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a comma-separated list. |
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:: |
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$ hroller -L |
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'Node Reboot Groups' |
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node1.example.com,node3.example.com,node5.example.com |
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node8.example.com,node6.example.com,node2.example.com |
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node7.example.com,node4.example.com |
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.. vim: set textwidth=72 : |
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.. Local Variables: |
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.. mode: rst |
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.. fill-column: 72 |
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.. End: |