LVM

From MyWiki

Statement

In a virtual environment, disk drives can be expanded with just a simple line command. These kinds of capabilities renders moot the value that LVM brings to the table. As a result, LVM in virtual servers is a liability, and we can all save ourselves some headaches by purging it from our system.

Use this procedure to get rid of it.

Procedure

• Shut down the VM

• Back up the VM

• Using the VMware Console application, create a new IDE disk at least as large as the current disk. Do not allocate all disk space now. Split into 2GB files. The equivalent command line command is:

vmware-vdiskmanager -c -s 20Gb -a ide -t 1 ideDisk0.vmdk

• Assign the new virtual disk to the VM (and take note of the current assignments for the devices). For example:

The current disk is at IDE 0:0  (corresponding to /dev/sda)
The new     disk is at IDE 0:1  (corresponding to /dev/sdb)

• Boot the VM from CD using a rescue ISO file
  • IMPORTANT!! On the boot menu, add the boot time parameter selinux=0 to disable SELinux
  • Mount the file systems read-only
  • Your old file systems will be mounted at /mnt/sysimage

• fdisk /dev/sdb (the new disk) and create the following partitions

             Device Boot  Start   End   Blocks  Id  System
(primary) /dev/sdb1   *       1    25   (200M)  83  Linux 
(primary) /dev/sdb2          26   150  (1024M)  82  Linux swap
(primary) /dev/sdb3         151  2610    (all)  83  Linux

• Make the ext3 filesystems

mkfs.ext3 -L /boot /dev/sdb1
mkfs.ext3 -L /     /dev/sdb3

• Label the swap partition too

mkswap -L swap2 /dev/sdb2

• Verify your labels are correct

e2label /dev/sdb1   
e2label /dev/sdb3

• Mount the new file systems

mkdir /tmp/newboot
mkdir /tmp/newroot
mount -t ext3 /dev/sdb1 /tmp/newboot
mount -t ext3 /dev/sdb3 /tmp/newroot

• Copy all files from old disk to new disk

cd /tmp/newboot
cp -ax /mnt/sysimage/boot/* .
cd /tmp/newroot
cp -ax /mnt/sysimage/* .

• Edit your new grub.conf file /tmp/newboot/grub/grub.conf and change the root parameter of the kernel line(s)

kernel /vmlinuz... ro root=LABEL=/

• Edit your new fstab file /tmp/newroot/etc/fstab and update the mount labels

LABEL=/       /      ext3  defaults  1 1
LABEL=/boot   /boot  ext3  defaults  1 2
...
LABEL=swap2   swap   swap  defaults  0 0

• Shut down the VM

• Reconfigure the disk drives in VMWare Console
  • Remove the old disk drive
  • Assign the new disk drive to IDE 0:0

• Review the vmx file and cleanup as necessary.
  • delete references to ide0:1 (or whatever the old assignment was)

• Boot the VM from CD using a rescue ISO file
  • No need to disable selinux this time
  • Allow the file systems to be mounted read write
  • Your (new & only) file system will be mounted at /mnt/sysimage

• Install the master boot record

grub
root (hd0,0)
setup (hd0)
quit

• Shutdown the VM

• In VMware Console, set the CD-ROM to *not* be connected at startup

• Boot the VM from the hard drive

• Rebuild initrd (to remove the reference to VolGroup00 LogVol00)

sudo su -
cd /boot
mkdir backup
cp initrd-2.6.20-1.2320.fc5.img backup
mkinitrd -f initrd-2.6.20-1.2320.fc5.img 2.6.20-1.2320.fc5

• Reboot the VM again, just to watch it come up cleanly so you know everything works