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hroller - Cluster rolling maintenance scheduler for Ganeti


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... ] [ --node-tags tag,.. ] [ --skip-non-redundant ]

[ --offline-maintenance ] [ --ignore-non-redundant ]

Reporting options:

[ -v... | -q ] [ -S file ] [ --one-step-only ] [ --print-moves ]


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 (currently RAPI and LUXI), the
master node is scheduled as the last node in the last reboot group. Apart from this
restriction, larger reboot groups are put first.

hroller will view the nodes as vertices of an undirected graph, with two kind of edges.
Firstly, there are edges from the primary to the secondary node of every instance.
Secondly, two nodes are connected by an edge if they are the primary nodes of two
instances that have the same 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 can then simultaneously migrate all instance off to their respective secondary
nodes, and it is safe to reboot them simultaneously.


For a description of the standard options check htools(1) and hbal(1).

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

--node-tags tag,...
Restrict to nodes having at least one of the given tags.

Also plan moving secondaries out of the nodes to be rebooted. For each instance
the move is at most a migrate (if it was primary on that node) followed by a
replace secondary.

Restrict to nodes not hosting any non-redundant instance.

Pretend that all instances are shutdown before the reboots are carried out. I.e.,
only edges from the primary to the secondary node of an instance are considered.

Pretend that the non-redundant instances do not exist, and only take instances with
primary and secondary node into account.

Restrict to the first reboot group. Output the group one node per line.

After each group list for each affected instance a node where it can be evacuated
to. The moves are computed under the assumption that after each reboot group, all
instances are moved back to their initial position.

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