A possibility I just debugged for a non-booting system. If there is a partition table on the underlying device then that device is not detected as an LVM1/2 member in at least one version of udevd, and won't be seen nor turned on automatically by the systemd-udev code. lvm vgchange -ay worked to enable it (emergency mode, it was the root pv--no udevd involvement) and eventually I found the partition table and removed it and the machine would then boot without needing a manual intervention. dd if=/dev/zero of=device bs=512 count=1 was used once we determined there was a partition signature still left (after partition deletion with fdisk, still had a header), examined with dd if=/dev/device bs=512 count=1 | xxd found 4 non-zero bytes in the block. On Sun, Sep 26, 2021 at 9:22 AM alessandro macuz <alessandro.macuz@xxxxxxxxx> wrote: > > Thanks Roger, Zdenek, > > I have my ZVOL on my NAS exposed as LUNs. The initiator were switched off and for unknown reason I found my NAS switched off as well. > It had run for long and I feared the worst (CPU/motherboard/etc). Instead once powered up everything started to work again but the LUNs that seemed to jeopardized. > I have many ZVOLs used by ESXi in which I have EVE-NG who uses LVM and such ZVOLs have the same size so I wanted to inspect them to check the hostname. > > Now some LUNs started to work normally, some others still behave weirdly. I will run pvs on them with extra debugs to see what's going on. > > Many thanks, > > Alex > > Le jeu. 23 sept. 2021 à 23:48, Roger Heflin <rogerheflin@xxxxxxxxx> a écrit : >> >> If you have lvmetad running and in use then the lvm commands ask it >> what the system has on it. >> >> I have seen on random boots fairly separated systems (rhel7 versions, >> and many years newer fedora systems) at random fail to find one or >> more pv.s >> >> I have disabled it at home, and in my day job we have also disabled >> (across 20k+ systems) as we confirmed it had inconsistency issues >> several times on a variety of our newest installs. >> >> Stopping lvmetad and/or restarting it would generally fix it. But >> it was a source of enough random issues(often failure to mount on a >> boot, so often issues that resulted in page-outs to debug) and did >> not speed things up much enough to be worth it even on devices with >> >2000 SAN volumes. >> >> On Thu, Sep 23, 2021 at 8:52 AM Zdenek Kabelac <zkabelac@xxxxxxxxxx> wrote: >> > >> > Dne 22. 09. 21 v 18:48 alessandro macuz napsal(a): >> > > fdisk correctly identifies the extended partition as 8e. >> > > I wonder which kind of data lvmdiskscan and pvs use in order to list LVM >> > > physical volumes. >> > > Does PVS check some specific metadata within the partition without just >> > > relying on the type of partition displayed by fdisk? >> > > >> > > >> > >> > Hi >> > >> > Yes - PVs do have header signature keeping information about PV attributes >> > and also has the storage area to keep lvm2 metadata. >> > >> > Partition flags known to fdisk are irrelevant. >> > >> > >> > Regards >> > >> > Zdenek >> > >> > _______________________________________________ >> > linux-lvm mailing list >> > linux-lvm@xxxxxxxxxx >> > https://listman.redhat.com/mailman/listinfo/linux-lvm >> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ >> > _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
