[linux-lvm] Question about speed of boot with mirror and lvm

[Georges Giralt]

Hello,

I've a PC with Ubuntu 18.04.1 LTS.

It uses a raid 1 mirror array to make one of the PV of my LVM setup. MD
metadata is version 0.9 so at the end of the two devices.

The LVM is :

# lvs --version
  LVM version:     2.02.176(2) (2017-11-03)
  Library version: 1.02.145 (2017-11-03)
  Driver version:  4.37.0
  Configuration:   ./configure --build=x86_64-linux-gnu --prefix=/usr
--includedir=${prefix}/include --mandir=${prefix}/share/man
--infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var
--disable-silent-rules --libdir=${prefix}/lib/x86_64-linux-gnu
--libexecdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run
--disable-maintainer-mode --disable-dependency-tracking --exec-prefix=
--bindir=/bin --libdir=/lib/x86_64-linux-gnu --sbindir=/sbin
--with-usrlibdir=/usr/lib/x86_64-linux-gnu --with-optimisation=-O2
--with-cache=internal --with-clvmd=corosync --with-cluster=internal
--with-device-uid=0 --with-device-gid=6 --with-device-mode=0660
--with-default-pid-dir=/run --with-default-run-dir=/run/lvm
--with-default-locking-dir=/run/lock/lvm --with-thin=internal
--with-thin-check=/usr/sbin/thin_check
--with-thin-dump=/usr/sbin/thin_dump
--with-thin-repair=/usr/sbin/thin_repair --enable-applib
--enable-blkid_wiping --enable-cmdlib --enable-cmirrord
--enable-dmeventd --enable-dbus-service --enable-lvmetad
--enable-lvmlockd-dlm --enable-lvmlockd-sanlock --enable-lvmpolld
--enable-notify-dbus --enable-pkgconfig --enable-readline
--enable-udev_rules --enable-udev_sync

#

Which is the standard Ubuntu LVM.

Since the upgrade to 18.04 booting is very slow as the kernel/boot has
to scan for all the devices.

I've followed the previous discussion about LVM and MD, did not
understand everything of it so I have a question : How could I speed up
the boot process ? Is masking one of the two disks in lvm.conf with a
filter is a good idea ? Or am I dumb ?

Many thanks in advance for your help and advice.