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--- docs:tips_n_tricks:lvm.html [12.07.2014 17:24 CEST] – [Get rid of left over /dev/dm-XXX nodes] peter
+++ docs:tips_n_tricks:lvm.html [31.07.2018 11:12 CEST] (current) – peter
@@ Line 1: / Line 1: @@
 ====== LVM ======
+{{entry>Linux}}
+{{entry>LVM}}
+{{tag>Linux LVM}}
 ===== Get rid of detatched PVs =====
-After removing a LVM physical device without unounting and deactivating the volumes first, you see this kind of error:
+After removing a LVM physical device without unmounting and deactivating the volumes first, you see this kind of error:
   ~ # pvs
@@ Line 32: / Line 35: @@
 ... and your //lvm// commands are quiet again :-)
-{{entry>Linux}}
+===== Boot with /usr etc. on LVM =====
-{{entry>LVM}}
-{{tag>Linux LVM}}
+Recent Ubuntu and Mint distributions seem to have trouble booting systems where relevant filesystems on LVM are referenced by label or uuid instead of ''/dev/''... .
+Tracking this down on Mint 18.2 lead me to the file ''/usr/share/initramfs-tools/scripts/local-block/lvm2'', where ''lvm lvchange'' is only called for devices matching the pattern ''/dev/*/*''
+//enigmaticPhysicist// on //Ask Ubuntu// regarding [[https://askubuntu.com/questions/551446/cant-find-lvm-root-dropped-back-to-initramfs|Can't find LVM root dropped back to initramfs]] had a solution to this by adding an initrd script:
+<code bash /etc/initramfs-tools/scripts/local-top/forcelvm>
+#!/bin/sh
+PREREQ=""
+prereqs()
+{
+   echo "$PREREQ"
+}
+case $1 in
+prereqs)
+   prereqs
+   exit 0
+   ;;
+esac
+. /scripts/functions
+# Begin real processing below this line
+# This was necessary because ubuntu's LVM autodetect is completely broken. This
+# is the only line they needed in their script. It makes no sense.
+# How was this so hard for you to do, Ubuntu?!?!?
+lvm vgchange -ay
+</code>
+__N.B.:__ Ubuntu Bug [[https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/1573982|#1573982]] seems to handle this.
+{{entry>booting}}
+{{entry>initrd}}
+{{tag>booting initrd}}