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Merge pull request #36241 from jan--f/c-v-mpath-support

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ceph-volume: support for mpath devices
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Jan Fajerski 2020-09-01 13:29:32 +02:00 committed by GitHub
commit cdd333a29f
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2 changed files with 12 additions and 20 deletions
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28
doc/ceph-volume/lvm/prepare.rst
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@ -253,28 +253,20 @@ work for both bluestore and filestore OSDs::
``multipath`` support
---------------------
Devices that come from ``multipath`` are not supported as-is. The tool will
refuse to consume a raw multipath device and will report a message like::
``multipath`` devices are support if ``lvm`` is configured properly.
--> RuntimeError: Cannot use device (/dev/mapper/<name>). A vg/lv path or an existing device is needed
**Leave it to LVM**
The reason for not supporting multipath is that depending on the type of the
multipath setup, if using an active/passive array as the underlying physical
devices, filters are required in ``lvm.conf`` to exclude the disks that are part of
those underlying devices.
Most Linux distributions should ship their LVM2 package with
``multipath_component_detection = 1`` in the default configuration. With this
setting ``LVM`` ignores any device that is a multipath component and
``ceph-volume`` will accordingly not touch these devices.
It is unfeasible for ceph-volume to understand what type of configuration is
needed for LVM to be able to work in various different multipath scenarios. The
functionality to create the LV for you is merely a (naive) convenience,
anything that involves different settings or configuration must be provided by
a config management system which can then provide VGs and LVs for ceph-volume
to consume.
This situation will only arise when trying to use the ceph-volume functionality
that creates a volume group and logical volume from a device. If a multipath
device is already a logical volume it *should* work, given that the LVM
configuration is done correctly to avoid issues.
**Using filters**
Should this setting be unavailable, a correct ``filter`` expression must be
provided in ``lvm.conf``. ``ceph-volume`` must not be able to use both the
multipath device and its multipath components.
Storing metadata
----------------

4
src/ceph-volume/ceph_volume/util/disk.py
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@ -330,7 +330,7 @@ def is_device(dev):
# use lsblk first, fall back to using stat
TYPE = lsblk(dev).get('TYPE')
if TYPE:
return TYPE == 'disk'
return TYPE in ['disk', 'mpath']
# fallback to stat
return _stat_is_device(os.lstat(dev).st_mode)
@ -747,7 +747,7 @@ def get_devices(_sys_block_path='/sys/block'):
for block in block_devs:
devname = os.path.basename(block[0])
diskname = block[1]
if block[2] != 'disk':
if block[2] not in ['disk', 'mpath']:
continue
sysdir = os.path.join(_sys_block_path, devname)
metadata = {}