On Wed, Nov 15, 2023 at 07:35:49AM +0000, Martin Wilck wrote: > How would that addition of the multipath device come to pass? > By someone explicitly calling "lvmdevices" on it? Yes, by running lvmdevices --adddev /dev/mapper/mpatha, or by running lvmdevices --update, which replaces a componenet device with the multipath device. > 1 - someone creates a PV on a normal single-path SCSI device > 2 - on subsequent boot, a new path has been added (e.g. by a Fibre > Channel zoning change) > 3 - what happens before the user makes any change to system.devices? > a) LVM attempts to add one of the SCSI (path) devices as PV > (which might be grabbed by multipathd already) > b) LVM attempts to add the multipath device automatically, > somehow figuring out what happened > c) neither is attempted, and the PV is missing If a scsi device suddenly becomes a multipath component, then C. The component device is ignored, the PV is missing, and lvm prints: WARNING: devices file is missing /dev/mapper/mpatha (253:1) using multipath component /dev/sda. See lvmdevices --update for devices file update. https://sourceware.org/git/?p=lvm2.git;a=blob;f=lib/filters/filter-mpath.c;h=854c26a7c7284c9e566dbd89ea899e554a1c8ed9;hb=HEAD#l37 Maybe there's something better we could do there. Dave
