Ever wanted to transfer multiple LVM volumes from one machine to other? Ever tried it? It's not hard, but it requires a lot of (manual) steps.

transfer_lvm_volume.rb

#!/usr/bin/env ruby
#
# == History
# Ever wanted to transfer multiple LVM volumes from one machine to other?
# Ever tried it? It's not hard, but it requires a lot of (manual) steps.
# Things get especially annoying if you want to test it first and than
# transfer everything ASAP. If you like to automate things, you can try 
# this script. It uses LVM2 snapshot mechanism, so in theory you don't 
# need to stop any service using the volume. Of course this will ensure
# only LVM/filesystem-level consistency, not application-level sonsistency!
#
# == Requirements
# 1) This script executable
# 2) Passwords-less sudo on destination machine
# 3) Sudo rights on source machine
# 4) Pubkey SSH authentication from source to destination machine
# 5) Installed "pv" - shows transfer progress
#
# == Example run:
# sudo /usr/local/sbin/transfer_lvm.rb
# >>> get size of partition
# lvs /dev/vg00/db01 -o LV_SIZE --noheadings --units G --nosuffix
# Command took: 0.431847s
# >>> delete possible old snapshot
#lvremove -f /dev/vg00/db01_snap
#    One or more specified logical volume(s) not found.
# Command took: 0.416606s
# >>> delete possible old remote partition
# ssh snap@newkulik 'sudo lvremove -f /dev/vg0/db01'
#   One or more specified logical volume(s) not found.
# Command took: 0.270644s
# >>> create snapshot
# lvcreate -L2G -s -n db01_snap /dev/vg00/db01
# Command took: 0.918021s
# >>> create partition on remote end
# ssh snap@newkulik 'sudo lvcreate -L10.49G -n db01 /dev/vg0'
# Command took: 0.33421s
# >>> transfer data
# dd if=/dev/vg00/db01_snap bs=4096 | pv | gzip | ssh snap@newkulik 'gzip -d | sudo dd of=/dev/vg0/db01' bs=4096
# 9.77GB 0:05:51 [28.5MB/s] [        <=>       ]2560000+0 records in
# Command took: 353.581616s
#
# == Configuration
# List all partitions you want to transfer
PARTITIONS = [ 'db01', 'db02', 'db03' ]
# Source LVM2 volume group
SRC_VG = '/dev/vg00'
# Destination LVM2 volume group
DST_VG = '/dev/vg0'
# How do you connect via SSH from source to destination machine?
REMOTE = 'snap@remotemachine'

def runme(cmd)
  puts cmd
  start = Time.now
  ret = `#{cmd}`
  diff = Time.now - start
  puts "Command took: #{diff}s\n"
  return ret
end

PARTITIONS.each do |orig_name|
  orig     = "#{SRC_VG}/#{orig_name}"
  src_name = "#{orig_name}_snap"
  src      = "#{SRC_VG}/#{src_name}"
  dst      = "#{DST_VG}/#{orig_name}"

  puts ">>> get size of partition"
  size = runme("lvs #{orig} -o LV_SIZE --noheadings --units G --nosuffix").strip.to_f

  # get size of snapshot
  snap_size = (size/10).ceil

  puts ">>> delete possible old snapshot"
  runme("lvremove -f #{src}")

  puts ">>> delete possible old remote partition"
  runme("ssh #{REMOTE} 'sudo lvremove -f #{dst}'")

  puts ">>> create snapshot"
  runme("lvcreate -L#{snap_size}G -s -n #{src_name} #{orig}")

  puts ">>> create partition on remote end"
  runme("ssh #{REMOTE} 'sudo lvcreate -L#{size}G -n #{orig_name} #{DST_VG}'")

  puts ">>> transfer data"
  runme("dd if=#{src} bs=4096 | pv | gzip | ssh #{REMOTE} 'gzip -d | sudo dd of=#{dst}' bs=4096")
end