Added howto for extending a logical volume

knowledge base/resize a logical volume.md

@@ -0,0 +1,34 @@
+# Resize a Logical Volume
+
+## TL;DR
+
+```sh
+# Disk partition: /dev/sda2
+# Logical volume: rootvg-rootlv
+
+# Extend the partition.
+# Optional; required only when there isn't enough space left on the disk.
+sudo growpart '/dev/sda' '2'
+
+# Extend the physical volume.
+# Optional; required only when there isn't enough space left in the volume.
+sudo pvresize '/dev/sda2'
+
+# Extend the file system to the desired size.
+sudo lvextend -rL '48G' '/dev/mapper/rootvg-rootlv'
+```
+
+```yaml
+#cloud-config
+
+# 'growpart' only extends partitions to fill the available free space.
+# At the time of writing there is no way to limit the expansion.
+growpart:
+  mode: auto
+  devices:
+    - /
+
+runcmd:
+  - pvresize '/dev/sda2'
+  - lvextend -rL '48G' '/dev/mapper/rootvg-rootlv'
+```