try "pvscan -vvv 2>&1 | grep md" and carefully look at that output. I would suspect a LVM filter in /etc/lvm/lvm.conf is blocking /dev/md0 and allowing in /dev/md/0. grep -i filter /etc/lvm/lvm.conf should show all of the commented out and uncommented filters in the file, it could be that the default filter in lvm changed. On Fri, Jun 29, 2018 at 6:42 AM, Hans Deragon <hans@xxxxxxxxxxx> wrote: > Found the solution, but it is odd. > > Both following commands mount the RAID 10, but LVM2 mounts > (automatically) only when the second form is used. > > mdadm --verbose --assemble /dev/md0 # RAID 10 assembled, but no LVM2. > mdadm --verbose --assemble /dev/md/0 # RAID 10 assembled, LVM2 works. > > I find this a bit disappointing. I do not understand the "magic" behind > this kind of behaviour and I wish there were commands to tell LVM2 to > look and find the physical volume in "md0". Comments are welcomed. > > I send my thanks to Chris Murphy for his response. > > Best regards, > Hans Deragon > > P.S. Sorry for the long delay between posts; it took me a while to find > this out. > > > On 2018-06-05 09:34 PM, Hans Deragon wrote: >> Greetings, >> >> Under Linux Kernel 4.4.0-127-generic, Ubuntu 16.04 LTS Xenial Xerus, I >> successfully created a healthy raid10 using 4x4Tib, LVM2 and ext4. >> >> When I boot into a USB keyfob installed with Ubuntu 18.04 LTS Bionic >> Beaver, Linux Kernel 4.15.0-20-generic #21-Ubuntu SMP, the system cannot >> find the LVM2 physical volume. >> >> Under Ubuntu 18.04 (USB keyfob), I run: >> >> $ apt install mdadm >> ... >> $ mdadm --verbose --assemble /dev/md0 # Works! >> $ cat /proc/mdstat # Shows raid. >> Personalities : [raid10] [linear] [multipath] [raid0] [raid1] [raid6] >> [raid5] [raid4] >> md0 : active raid10 sdh[0] sdb[1] sdc[2] sdd[3] >> 7813774336 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU] >> bitmap: 0/59 pages [0KB], 65536KB chunk >> >> $ pvscan # Shows nothing! >> $ >> >> Why can't pvscan find the physical volume? Remember, this is a %100 >> healthy working RAID10. If I remove the USB keyfob and reboot into my >> Ubuntu 16.04 LTS system, the whole drive (ext4) gets automatically >> mounted properly, all the time without any errors. It works flawlessly >> under Linux Kernel 4.4.0-127-generic, but not with Linux Kernel >> 4.15.0-20-generic #21. >> >> On the web, I find only people having defective RAIDs when pvscan >> returns nothing. Is there a way to force pvscan/LVM2 to consider /dev/md0? >> >> Unfortunately, I cannot upgrade to Ubuntu 18.04/Linux Kernel 4.15.0 >> until this is resolved. >> >> Best regards, >> Hans Deragon >> > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
