Resizing with LVM

I am running a proxmox server with several virtual machines and noticed that I have more disk space configured on the virtual machines then I have on the partition they are running on. Here are the steps I took to increase the size of the ext3 partition hosting the vms.

1. View the mount points to determine what logical volume the vms are on

~# mount
/dev/pve/root on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
procbususb on /proc/bus/usb type usbfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/mapper/pve-data on /var/lib/vz type ext3 (rw)
/dev/cciss/c0d0p1 on /boot type ext3 (rw)


2. View the logical volume to determine what volume group it is on:

~# lvdisplay /dev/mapper/pve-data
  --- Logical volume ---
  LV Name                /dev/pve/data
  VG Name                pve


3. View the volume group to be sure there is room for expansion:

~# vgdisplay pve
  --- Volume group ---
  VG Name               pve
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  2236
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               3
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               477.93 GB
  PE Size               4.00 MB
  Total PE              122351
  Alloc PE / Size       44928 / 175.50 GB
  Free  PE / Size       77423 / 302.43 GB
  VG UUID               ThGaW0-KPoF-ZA3V-jgxE-zv6d-jaMY-Pc8Y1W

4. Extend the logical volume (-L flag as used below allows you to specify the new size of the volume):

~# lvextend -L150G /dev/pve/data
  Extending logical volume root to 150.00 GB
  Logical volume root successfully resized

5. Resize the ext3 partition

~# resize2fs /dev/pve/data
resize2fs 1.41.3 (12-Oct-2008)
Filesystem at /dev/pve/data is mounted on /var/lib/vz; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 10
Performing an on-line resize of /dev/pve/data to 39321600 (4k) blocks.
The filesystem on /dev/pve/data is now 39321600 blocks long.

Pretty easy.

Create copy of VM on Proxmox

1. Ssh into the Proxmox server as root.
2. Run "vzdump" with desired VMID.

$vzdump 101

3. Run "qmrestore" with unused VMID. Your dump file should be located in /var/lib/vz/dump.

$qmrestore /var/lib/vz/dump/vzdump-qemu-101-2011_01_10-11_13_30.tar 102

I tested this with a Ubuntu server 10.10 VM.  From the Proxmox console I deleted the network device and recreated it to be sure it had a unique MAC address (not sure if that was necessary).  I started the new VM, logged in, and changed the hostname and some values for the apache server.

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**UPDATE (02/09/2011)**
I noticed that when running the this command I would see:

INFO: mode failure - unable to dump into snapshot (use option --dumpdir)

After some intrepid googling I discovered this was because the dump was being created on the same lvm group vzdump had to suspend the vm to do the backup.  To avoid this (since I was backing up a live webserver) I mounted a windows share (on a domain) and pointed the dump to there.

1. Mount the windows share to the /mnt/share directory (be sure that directory exists)

$mount -t smbfs //server/share /mnt/share -o username=domainuser

2. Run vzdump with the --dumpdir option

$vzdump --dumpdir /mnt/share/dumps 101

Linux DNS entry

As I was playing with linux servers I noticed that a DNS entry was not being created when I added new servers to the network. After some googling I found the solution. If you are running dhcp3 update your dhclient.conf (mine was under /etc/dhcp3) to include the following line:

send fqdn.server-update on;

Restart networking.