What is LVM?

LVM stage for Logical Volume Manager. LVM for Linux was developed by RedHat. Here I particularly reference lvm2.

LVM2 and mkinitramfs

LVM2 support is enabled by specifying --with-lvm2 switch. Of course you should have lvm2 binary in your path. By default LVM2 volume device files are only created under /dev/mapper, i.e. no /dev/disk/by-uuid links. Since LVM2 relies on device-mapper, you'll need to adjust device-mapper related udev rules. See DMrules for more info.

Implementation

Plugin code is rather simple:

#> cat /usr/share/mkinitramfs/lvm2
# Register our scan function
SCAN="lvm2_scan $SCAN"

function lvm2_scan() {
        grep -q dm_mod /proc/modules || modprobe dm_mod
        lvm vgscan --ignorelockingfailure >/dev/null 2>&1 || die
        lvm vgchange -ay --ignorelockingfailure >/dev/null 2>&1 || die
        return 1
}