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HROLLER(1) Ganeti | Version @GANETI_VERSION@

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NAME

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hroller \- Cluster rolling maintenance scheduler for Ganeti

SYNOPSIS

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**hroller** {backend options...} [algorithm options...] [reporting options...]

**hroller** \--version

Backend options:

{ **-m** *cluster* | **-L[** *path* **]** | **-t** *data-file* |

**-I** *path* }

Algorithm options:

**[ -O *name...* ]**

Reporting options:

**[ -v... | -q ]**

**[ -S *file* ]**

DESCRIPTION

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hroller is a cluster maintenance reboot scheduler. It can calculate

which set of nodes can be rebooted at the same time while avoiding

having both primary and secondary nodes being rebooted at the same time.

ALGORITHM FOR CALCULATING OFFLINE REBOOT GROUPS

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

hroller will view the nodes as vertices of an undirected graph,

connecting by instances which have both a primary and a secondary node.

It will then color the graph using a few different heuristics, and

return the minimum-size color set found. Node with the same color don't

share an edge, and as such don't have an instance with both primary and

secondary node on them, so they are safe to be rebooted concurrently.

OPTIONS

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Currently only standard htools options are supported. For a description of them

check **htools**\(7) and **hbal**\(1).

BUGS

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The master node should be always the last node of the last group, or anyway

somehow easily identifiable. Right now this is not done.

Offline nodes should be ignored.

Filtering by nodegroup should be allowed.

If instances are online the tool should refuse to do offline rolling

maintenances, unless explicitly requested.

End-to-end shelltests should be provided.

Online rolling maintenances (where instance need not be shut down, but

are migrated from node to node) are not supported yet. Hroller by design

should support them both with and without secondary node replacement.

EXAMPLE

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Note that these examples may not for the latest version.

Offline Rolling node reboot output

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With the default options, the program shows one reboot group per line as

a comma-separated list.

    $ hroller

    'Node Reboot Groups'

    node1.example.com,node3.example.com,node5.example.com

    node8.example.com,node6.example.com,node2.example.com

    node7.example.com,node4.example.com

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