When last we joined our intrepid hero, back in *checks notes* 2009.. I was working at a university, helping to run their internal cloud and they had a policy of setting up LVM for all the linux VMs, and I wrote the blog post so I could remember how to do online resizes.

I no longer work in that job, country, or sector, but I still use LVM on my home VMs, so still need them sometimes. However today I needed to extend an LVM containing a PV that was the entire disk, not just a partition, and the instructions didn’t work for me, so this is what I had to do..

root@serverName:~# df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/vgRoot-lvRoot   15G  7.4G  6.6G  53% /
/dev/mapper/vgData-lvData   98G   93G     0 100% /data
#
# Firstly, we see that the volume is 100% full, so we extend in VMWare to 200GB
# and rescan partition geometry
#
root@serverName:/data# echo '1' > /sys/class/scsi_disk/32\:0\:1\:0/device/rescan 
#
# Next, run fdisk for info only, to check it's seen as a 200GB device. We don't make
# any changes though!
#
root@serverName:/data# fdisk /dev/sdb

Welcome to fdisk (util-linux 2.34).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

The old LVM2_member signature will be removed by a write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x44d591a2.

Command (m for help): p
Disk /dev/sdb: 200 GiB, 214748364800 bytes, 419430400 sectors
Disk model: Virtual disk    
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x44d591a2

Command (m for help): q
#
# Correct new drive size is seen, so we rescan/resize the PV
#
root@serverName:/data# pvresize /dev/sdb
  Physical volume "/dev/sdb" changed
  1 physical volume(s) resized or updated / 0 physical volume(s) not resized
#
# Next, we extend the LV into the new space
#
root@serverName:/data# lvextend -L+100G /dev/vgData/lvData 
  Size of logical volume vgData/lvData changed from <100.00 GiB (25599 extents) to <200.00 GiB (51199 extents).
  Logical volume vgData/lvData successfully resized.
#
# Verify the new space is seen in the LV
#
root@serverName:/data# lvdisplay
  --- Logical volume ---
  LV Path                /dev/vgData/lvData
  LV Name                lvData
  VG Name                vgData
  LV UUID                WsxT1O-jzLF-D4fP-1AN5-ApQs-Kx6i-yQx2iA
  LV Write Access        read/write
  LV Creation host, time ubuntu-server, 2020-08-09 05:07:00 +0000
  LV Status              available
  # open                 1
  LV Size                <200.00 GiB
  Current LE             51199
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
   
  --- Logical volume ---
  LV Path                /dev/vgRoot/lvRoot
  LV Name                lvRoot
  VG Name                vgRoot
  LV UUID                9bpv9H-q53y-TwUC-n8k5-vYgi-y0ay-lBY367
  LV Write Access        read/write
  LV Creation host, time ubuntu-server, 2020-08-09 05:07:01 +0000
  LV Status              available
  # open                 1
  LV Size                <15.00 GiB
  Current LE             3839
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
#
# Finally resize the filesystem inside the LV
#
root@serverName:/data# resize2fs /dev/vgData/lvData 
resize2fs 1.45.5 (07-Jan-2020)
Filesystem at /dev/vgData/lvData is mounted on /data; on-line resizing required
old_desc_blocks = 13, new_desc_blocks = 25
The filesystem on /dev/vgData/lvData is now 52427776 (4k) blocks long.
#
# And we're done!
#
root@serverName:/data# df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/vgRoot-lvRoot   15G  7.4G  6.6G  53% /
/dev/mapper/vgData-lvData  197G   93G   95G  50% /data
root@serverName:/data#