A Fabric script for striping EBS volumes

Here's a short Fabric script which might be useful to people who need to stripe EBS volumes in Amazon EC2. Striping is recommended if you want to improve the I/O of your EBS-based volumes. However, striping won't help if one of the member EBS volumes goes AWOL or suffers performance issues. In any case, here's the Fabric script:

import commands
from fabric.api import *

# Globals

env.project='EBSSTRIPING'
env.user = 'myuser'

DEVICES = [
    "/dev/sdd",
    "/dev/sde",
    "/dev/sdf",
    "/dev/sdg",
]

VOL_SIZE = 400 # GB

# Tasks

def install():
    install_packages()
    create_raid0()
    create_lvm()
    mkfs_mount_lvm()

def install_packages():
    run('DEBIAN_FRONTEND=noninteractive apt-get -y install mdadm')
    run('apt-get -y install lvm2')
    run('modprobe dm-mod')
    
def create_raid0():
    cmd = 'mdadm --create /dev/md0 --level=0 --chunk=256 --raid-devices=4 '
    for device in DEVICES:
        cmd += '%s ' % device
    run(cmd)
    run('blockdev --setra 65536 /dev/md0')

def create_lvm():
    run('pvcreate /dev/md0')
    run('vgcreate vgm0 /dev/md0')
    run('lvcreate --name lvm0 --size %dG vgm0' % VOL_SIZE)

def mkfs_mount_lvm():
    run('mkfs.xfs /dev/vgm0/lvm0')
    run('mkdir -p /mnt/lvm0')
    run('echo "/dev/vgm0/lvm0 /mnt/lvm0 xfs defaults 0 0" >> /etc/fstab')
    run('mount /mnt/lvm0')

A few things to note:

• I assume that you already created and attached 4 EBS volumes to your instance with device names /dev/sdd through /dev/sdg; if your device names or volume count are different, modify the DEVICES list appropriately
• The size of your target RAID0 volume is set in the VOL_SIZE variable
• the helper functions are pretty self-explanatory: 
1. we use mdadm to create a RAID0 device called /dev/md0; we also set the block size to 64 KB via the blockdev call
2. we create a physical LVM volume on /dev/md0
3. we create a volume group called vgm0 on /dev/md0
4. we create a logical LVM volume called lvm0 of size VOL_SIZE, inside the vgm0 group
5. we format the logical volume as XFS, then we mount it and also modify /etc/fstab

That's it. Hopefully it will be useful to somebody out there.