From: Alfredo Deza Date: Tue, 13 Mar 2018 19:26:46 +0000 (-0400) Subject: doc/ceph-volume document multipath support X-Git-Tag: v13.1.0~567^2~2 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=1dca5eac386ff2f67f2449700cd4bf27b81dafda;p=ceph.git doc/ceph-volume document multipath support Signed-off-by: Alfredo Deza --- diff --git a/doc/ceph-volume/lvm/prepare.rst b/doc/ceph-volume/lvm/prepare.rst index 9c684c001382..2fa1e262405f 100644 --- a/doc/ceph-volume/lvm/prepare.rst +++ b/doc/ceph-volume/lvm/prepare.rst @@ -235,6 +235,33 @@ work for both bluestore and filestore OSDs:: ceph-volume lvm prepare --bluestore --data vg/lv --crush-device-class foo +.. _ceph-volume-lvm-multipath: + +``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:: + + --> RuntimeError: Cannot use device (/dev/mapper/). A vg/lv path or an existing device is needed + +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. + +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. + + Storing metadata ---------------- The following tags will get applied as part of the preparation process