[Bug 1807499] Re: 30 seconds boot delay when root fs is on lvm

[Eduard Hasenleithner]

A the moment I can see following solutions:

(1)
Make the lvchange_activate function in /usr/share/initramfs-tools/scripts/local-top/lvm2 a while loop which executes the "lvchange" command repeatedly until the root LV appears

(2)
Utilize udevd to create the LV devices while wait-for-root is waiting for the root LV to appear. A hack for doing so is to replace in /lib/udev/rules.d/69-lvm-metad.rules the line 96
  ACTION!="remove", ENV{LVM_PV_GONE}=="1", RUN+="/bin/systemd-run /sbin/lvm pvscan --cache $major:$minor --activate ay", GOTO="lvm_end"
with
  ACTION!="remove", RUN+="/sbin/lvm pvscan --cache $major:$minor --activate ay"

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Title:
  30 seconds boot delay when root fs is on lvm

Status in lvm2 package in Ubuntu:
  New

Bug description:
  On my system the root filesystem is located on a logical volume. I
  have constant boot delay of 30 seconds. My current conclusion is that
  this problem exists due to lvm performing the initramfs-tools local-
  top initialization incorrectly.

  According to initramfs-tools(8):
  local-top OR nfs-top After these scripts have been executed, the root  device  node is expected to be present (local) or the network interface is expected to be usable (NFS).

  But what /usr/share/initramfs-tools/scripts/local-top/lvm2 is simply
  try to activate the requested root volume by means of scanning the (at
  that moment) available block devices. What happens on my system is
  that local-top/lvm2 is executed before the pv block device (SATA-SSD)
  shows up. Then initramfs-tools calls the wait-for-root executable
  which waits for the root device node notification via udev.

  This has a (minimum) timeout of 30 seconds configured. This timeout is
  exceeded since nothing will make the root volume device to be created.
  Then later (I guess in local-block) the root volume device is created
  (since the pv is available).

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: lvm2 2.02.176-4.1ubuntu3
  ProcVersionSignature: Ubuntu 4.15.0-42.45-generic 4.15.18
  Uname: Linux 4.15.0-42-generic x86_64
  ApportVersion: 2.20.9-0ubuntu7.5
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Sat Dec  8 13:52:06 2018
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=de_AT.UTF-8
   SHELL=/bin/bash
  SourcePackage: lvm2
  UpgradeStatus: No upgrade log present (probably fresh install)

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