On 04/10/2017 03:32 PM, Sage Weil wrote: > On Mon, 10 Apr 2017, Loic Dachary wrote: >> Hi Sage, >> >> When the OSD is prepared, we add a --device-class option to ceph-disk >> that creates a device_class file and activate can use it use when >> creating the the OSD[1]. The ceph osd create command is given an >> additional optional argument (device class). If the device class >> argument is present, ceph osd create[2] creates a device entry in the >> crushmap (it currently does nothing with the crushmap) so that the >> corresponding device class can be preserved. This happens before >> update_crush_location[3] is called and since the device is not included >> in any crush tree it won't be used. >> >> I'm not happy about adding an argument to osd create. We could instead >> have a new dedicated command create-with-device-class but I like that >> even less. We could also add a "ceph osd crush create-device" and have >> ceph-disk call it right after "ceph osd create", followed by "ceph osd >> crush set-device-class". That would be my second favorite: the only >> drawback is having a multi-step device creation during activation but >> all steps are idempotents that should not be a problem. >> >> What do you think ? > > We're aiming toward a new osd create command anyway that does all of this > stuff at once (create osd id and set uuid, set cephx key, set lockbox key > for dmcrypt, add to crush map). Having it also set the device class seems > like an easy addition. I believe Joao has started or is about to start > work on this? > > In the meantime, I would do the simplest thing, which is probably just > calling 'ceph osd crush set-device-class'. It could be done before the > 'osd crush create-or-move' in OSD::update_crush_location(), Does that mean we should have a --device-class argument to ceph-osd --mkfs ? Or is there another way I'm not seeing ? > but then we'd > probably want to make it only set it if a device class isn't already set > (i.e., don't change it if the admin set it to something else). Or at some > convenient point during the initial activation that similarly avoids > clobbering the value if the admin set it... > > sage > -- Loïc Dachary, Artisan Logiciel Libre -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
