Some notes on LVM

Extending LV to new disks

If you try to create a PV on a disk with a signature you’ll get this:

[root@boomer ~]# pvcreate /dev/sdb
  Device /dev/sdb excluded by a filter.

1. Get rid of the signature with gdisk:

   [root@boomer ~]# gdisk /dev/sdb
   GPT fdisk (gdisk) version 1.0.4
   
   Partition table scan:
   MBR: protective
   BSD: not present
   APM: not present
   GPT: present
   
   Found valid GPT with protective MBR; using GPT.
   
   Command (? for help): x
   
   Expert command (? for help): z
   
   About to wipe out GPT on /dev/sdb. Proceed? (Y/N): Y
   GPT data structures destroyed! You may now partition the disk using fdisk or
   other utilities.
   Blank out MBR? (Y/N): Y
   

2. Now you can run pvcreate on each disk you need to add:

   [root@boomer ~]# pvcreate /dev/sdb
   Physical volume "/dev/sdb" successfully created.
   

3. Verify:

   [root@boomer ~]# lvmdiskscan
   /dev/fedora_boomer/root [      15.00 GiB]
   /dev/sda1              [     200.00 MiB]
   /dev/fedora_boomer/swap [       7.89 GiB]
   /dev/sda2              [     200.00 MiB]
   /dev/sda3              [       1.00 GiB]
   /dev/sda4              [      <2.73 TiB] LVM physical volume
   /dev/sdb               [      <2.73 TiB] LVM physical volume
   /dev/sdc               [      <2.73 TiB] LVM physical volume
   /dev/sdd               [      <2.73 TiB] LVM physical volume
   

4. Add new PVs to existing lv:

   [root@boomer ~]# vgextend fedora_boomer /dev/sdb
   Volume group "fedora_boomer" successfully extended
   

Create new Logical Volume

1. Make the new LV

   [root@boomer ~]# lvcreate -n libvirt -L 500G fedora_boomer
   Logical volume "libvirt" created.
   

2. Trust but verify

   [root@boomer ~]# lvs
   LV      VG           Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
   libvirt fedora_boomer -wi-a----- 500.00g
   root    fedora_boomer -wi-ao----  15.00g
   swap    fedora_boomer -wi-ao----   7.89g