Posts Tagged with lvm2

I’ve been a fan of virtual machines from early on, like KVM for instance. A greatly respected ex-coworker recommended Proxmox, which was the front end to a Type [1.5] hypervisor. He nonchalantly try to sell a few us on it from time to time and I think I failed to make note of how awesome it really was.

I use it daily and am sometimes asked to extend a user’s VM host’s disk. Usually, it to support development (storing test data) and not because of laziness or ignorance (needing more space for crap because they’re not sure how to keep it in check).

The process for increasing the size of your KVM disk is as follows.

Prerequisites

• KVM host
• KVM guest
• root access via command line
• VM ID
• Know your LVM
  • Group name; use vgdisplay
  • Logical volume name: use lvdisplay
  • Is it ext4 or xfs

Procedure

1. Shutdown your guest
   shutdown -hP now
2. Make a copy of your VM’s current disk
   cp /var/lib/images/vm-117.qcow2 /var/lib/images/vm-117.qcow2.orig
3. Increase the size of the disk image (CLI or GUI)
   qm resize <vmid> <disk> +<size>G
qemu-img resize ...
   Example:
   qm resize 117 /dev/sda +100%FREE
4. Convert VMDK to raw, if applicable
   qemu-img convert -O raw vm-117.qcow2 vm-117.raw
5. Start guest
6. On guest, enlarge the partition using a partition tool (Proxmox already has parted installed, you can use that if you prefer). If your disk already has a swap (id 82) partition, you will want to delete it and add it back to the end of the disk.  See this guide or the last step in this guide.
   fdisk /dev/sda
   Create a new partition to add to the new volume group
   type: primary
   start:<default value>
   end:<default value>
   type:8e
   write changes: w
7. Reboot or rescan partitions on guest
8. Initialize a disk or partition for use by LVM
   pvcreate /dev/sdX#
9. Verify your physical volumes
   pvdisplay
10. Add the partition to the partition map.  Confirm your partition is present using
    cat /proc/partitions
11. If your partition isn’t there, reboot or rescan
    partx /dev/sdX#
12. Get the name of your volume group
    vgdisplay
13. Extend your volume group by adding your new partition to it
    vgextend <vg_name> <partition>
14. Get the name of your logical volume root
    lvscan
15. Extend the logical volume (-r means you don’t have to run resize2fs separately)
    lvextend -r -l +100%FREE /dev/<vg_name>/<lv_root>
    Example:
    lvextend -l +100%FREE /dev/mapper/centos-root
16. Resize the filesystem (if you did not do a -r above).
    Determine your filesystem:
    mount | column -t
for ext4, use resize2fs /dev/mapper/centos-root (or value from mount command above)
    for xfs, use xfs_growfs /dev/mapper/centos-root (or value from mount command above)
17. Confirm larger size