The details provided by the fact under mounts yields the /dev/mapper/- for the device details.

I happened to come across an issue where I needed to dynamically create a new filesystem across SUSE, RH, and CentOS where the VGs names vary drastically (system,rootvg,vgroot,centos) for the / partition.

Using the mountpoints fact, I extracted the / vg with
Facter.value(:mountpoints)['/']['device'].split(' ')[0].split('/')[3].split('-')[0]
and the LV with
Facter.value(:mountpoints)['/']['device'].split(' ')[0].split('/')[3].split('-')[1]

Would it make any sense to do this within the mountpoints to provide that detail for LVM operations using mountpoints?

I'd like to implement some of your facts but I'm unsure as to where they should go. Is there a way to implement these w/o having to 'facter -p' (for custom facts)?

E.g. no /dev/md1 reported:

facter -p | grep partitions

partitions => {"sda1"=>{"size"=>"1951744", "label"=>"sysresccd:0", "filesystem"=>"linux_raid_member"}, "sda2"=>{"size"=>"1463193600", "label"=>"vmhost12:1", "filesystem"=>"linux_raid_member"}, "sdb1"=>{"size"=>"1951744", "label"=>"sysresccd:0", "filesystem"=>"linux_raid_member"}, "sdb2"=>{"size"=>"1463193600", "label"=>"vmhost12:1", "filesystem"=>"linux_raid_member"}, "sdc1"=>{"size"=>"1951744", "label"=>"sysresccd:0", "filesystem"=>"linux_raid_member"}, "sdc2"=>{"size"=>"1463193600", "label"=>"vmhost12:1", "filesystem"=>"linux_raid_member"}, "sdd1"=>{"size"=>"1951744", "label"=>"sysresccd:0", "filesystem"=>"linux_raid_member"}, "sdd2"=>{"size"=>"1463193600", "label"=>"vmhost12:1", "filesystem"=>"linux_raid_member"}}

But there is a /dev/md1 with partitions:

parted /dev/md1 print

Model: Linux Software RAID Array (md)
Disk /dev/md1: 2247GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number Start End Size Type File system Flags
1 1573kB 24.0GB 24.0GB primary linux-swap(v1)
2 24.0GB 54.0GB 30.0GB primary lvm
3 54.0GB 2247GB 2193GB primary lvm