[DRBD-user] drbd+lvm no bueno

[Veit Wahlich]

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).

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/.*/" ]

After editing the configuration, you might want to regenerate your
distro's initrd/initramfs to reflect the changes directly at startup.

Best regards,
// Veit