Bug#799781: device lock race condition between udev and multipathd may cause systemd to abort system boot

Baumgartner Niels, Bedag Niels.Baumgartner at bedag.ch
Mon Oct 5 14:30:47 UTC 2015

Hi Ritesh

> then you can mount the filesystem like this:
>  mount /dev/mapper/36000393000007d3901000000fef00a2d /mnt or this
>  mount /dev/disk/by-id/scsi-36000393000007d3901000000fef00a2d /mnt You should prefer the latter, as this will work whether or not multipath-tools is installed.

Ok, my /etc/fstab uses the /dev/mapper/<id> instead of /dev/disk/by-id/scsi-<id> 

/dev/mapper/vg_system-lv_system /       ext4    errors=remount-ro       0       1
# /boot was on /dev/sdb1 during installation
/dev/mapper/360060e80165082000001508200009083-part1     /boot   ext4    defaults        0       2
# swap was on /dev/sdb2 during installation
/dev/mapper/360060e80165082000001508200009083-part2     none    swap    sw      0       0

> Now, in a setup, if you mix Device Mapper LVM and Device Mapper Multipath, you need to ensure that the multipath map is created before LVM locks it.

How would I do this?

> And to LVM, you need to instruct that it should look for Physical Volumes in /dev/mapper/.
The following line is present from the default lvm.conf:
    scan = [ "/dev" ]

So here is what I could try:
1. install stable packages
2. change /etc/fstab to use /dev/disk/by-id devices.
3. change lvm.conf to 
  scan = ["/dev/disk/by-id/"]
4. update-initramfs
5. test again

This way the scsi devices should not be locked by lvm.
Might this work? Is there anything else I should do/change before testing again?

> What do you have to say about my explanation?

Sounds plausible. Let's put it to a test.


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