lvconvert --type writecache fails

[Mike Iversen]

Following the manpage
https://manpages.ubuntu.com/manpages/focal/man7/lvmcache.7.html

I am unable perform the below step

lvconvert --type writecache --cachevol fast vg/main

I receive the following error
  WARNING: Unrecognised segment type writecache
  Invalid argument for --type: writecache
  Error during parsing of command line.

This is a new installation of ubuntu server 20.04 running the default kernel (5.4.0-80-generic).

LVM Version
  LVM version: 2.03.07(2) (2019-11-30)
  Library version: 1.02.167 (2019-11-30)
  Driver version: 4.41.0
  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-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-dmeventd --enable-dbus-service --enable-lvmlockd-dlm --enable-lvmlockd-sanlock --enable-lvmpolld --enable-notify-dbus --enable-pkgconfig --enable-readline --enable-udev_rules --enable-udev_sync

Per the LVM commit history, this feature was added in 2.03.12
https://github.com/lvmteam/lvm2/blob/master/WHATS_NEW

This means the manpage is out of sync with what is in the repository.

Reference debian bug 939535 as it appears to be the same issue there as well (I'm assuming the manpage was lifted from debian?)

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=939535