mirror of https://github.com/ceph/ceph
38 lines
1.3 KiB
ReStructuredText
38 lines
1.3 KiB
ReStructuredText
.. _ceph-volume-systemd-api:
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systemd
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=======
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The workflow to *"activate"* an OSD is by relying on systemd unit files and its
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ability to persist information as a suffix to the instance name.
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``ceph-volume`` exposes the following convention for unit files::
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ceph-volume@<sub command>-<extra metadata>
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For example, this is how enabling an OSD could look like for the
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:ref:`ceph-volume-lvm` sub command::
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systemctl enable ceph-volume@lvm-0-8715BEB4-15C5-49DE-BA6F-401086EC7B41
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These 3 pieces of persisted information are needed by the sub-command so that
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it understands what OSD it needs to activate.
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Since ``lvm`` is not the only subcommand that will be supported, this
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is how it will allow other device types to be defined.
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At some point for example, for plain disks, it could be::
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systemctl enable ceph-volume@disk-0-8715BEB4-15C5-49DE-BA6F-401086EC7B41
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At startup, the systemd unit will execute a helper script that will parse the
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suffix and will end up calling ``ceph-volume`` back. Using the previous
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example for lvm, that call will look like::
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ceph-volume lvm activate 0 8715BEB4-15C5-49DE-BA6F-401086EC7B41
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.. warning:: These workflows are not meant to be public, but are documented so that
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it is clear what the tool is doing behind the scenes. Do not alter
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any of these values.
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