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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* }

**[ --force ]**

Algorithm options:

**[ -G *name* ]**

**[ -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.

For backends that support identifying the master node (currenlty

RAPI and LUXI), the master node is scheduled as the last node

in the last reboot group.

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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For a description of the standard options check **htools**\(7) and

**hbal**\(1).

\--force

  Do not fail, even if the master node cannot be determined.

BUGS

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Offline nodes should be ignored.

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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Offline Rolling node reboot output

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

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

a comma-separated list.

::

    $ hroller -L

    '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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