On Thu, Jul 26, 2018 at 04:32:17PM +0200, Veit Wahlich wrote: > Hi Eric, > > Am Donnerstag, den 26.07.2018, 13:56 +0000 schrieb Eric Robinson: > > Would there really be a PV signature on the backing device? I didn't > > turn md4 into a PV (did not run pvcreate /dev/md4), but I did turn > > the drbd disk into one (pvcreate /dev/drbd1).
Yes (please view in fixed with font): | PV signature | VG extent pool | |.... drbd1 .... .... .... .... | drbd metadata | |.... md4 .... .... .... .... .... .... .... ...|md metadata| |component|drives|.....|.....|...of...|md4......|.....|.....| > both DRBD and mdraid put their metadata at the end of the block device, > thus depending on LVM configuration, both mdraid backing devices as well > as DRBD minors bcking VM disks with direct-on-disk PVs might be detected > as PVs. > > It is very advisable to set lvm.conf's global_filter to allow only the > desired devices as PVs by matching a strict regexp, and to ignore all > other devices, e.g.: > > global_filter = [ "a|^/dev/md.*$|", "r/.*/" ] > > or even more strict: > > global_filter = [ "a|^/dev/md4$|", "r/.*/" ] Uhm, no. Not if he want DRBD to be his PV... then he needs to exclude (reject) the backend, and only include (accept) the DRBD. But yes, I very much recommend to put an explicit white list of the to-be-used PVs into the global filter, and reject anything else. Note that these are (by default unanchored) regexes, NOT glob patterns. (Above examples get that one right, though r/./ would be enough... but I have seen people get it wrong too many times, so I thought I'd mention it here again) > After editing the configuration, you might want to regenerate your > distro's initrd/initramfs to reflect the changes directly at startup. Yes, don't forget that step ^^^ that one is important as well. But really, most of the time, you really want LVM *below* DRBD, and NOT above it. Even though it may "appear" to be convenient, it is usually not what you want, for various reasons, one of it being performance. Cheers, -- : Lars Ellenberg : LINBIT | Keeping the Digital World Running : DRBD -- Heartbeat -- Corosync -- Pacemaker DRBD® and LINBIT® are registered trademarks of LINBIT __ please don't Cc me, but send to list -- I'm subscribed _______________________________________________ drbd-user mailing list drbd-user@lists.linbit.com http://lists.linbit.com/mailman/listinfo/drbd-user