Tag Archives: cloud

Ubuntu 12 + lxc + Rackspace

First let’s build an Ubuntu 12 server

cloud> servers create
Server name: lxc-host
Image ID: 125
Flavor ID: 3
   "server" : {
      "status" : "BUILD",
      "progress" : 0,
      "name" : "lxc-host",
      "imageId" : 125,
      "addresses" : {
         "private" : [
         "public" : [
      "flavorId" : 3,
      "hostId" : "c395c82dd1963e52098e77819fda2b86",
      "metadata" : {},
      "id" : 20898849

Make sure everything is up-to-date

root@lxc-host:~# apt-get update
root@lxc-host:~# apt-get upgrade

Install some necessary utilities for this.

root@lxc-host:~# apt-get install lxc debootstrap bridge-utils screen

Now we need to make the bridge in /etc/network/interfaces

# lxc bridge
auto lxcbr0
iface lxcbr0 inet static
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
        pre-down echo 0 > /proc/sys/net/ipv4/ip_forward
        pre-down iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
        bridge_ports none
        bridge_stp off

Activating the bridge…

root@lxc-host:~# ifup lxcbr0

Now it’s time to create the first container. The available templates should be listed here:

root@lxc-host:~# ls /usr/lib/lxc/templates/
lxc-busybox  lxc-debian  lxc-fedora  lxc-opensuse  lxc-sshd  lxc-ubuntu  lxc-ubuntu-cloud

To be special let’s make a fedora guest

root@lxc-host:~# vim /etc/lxc/auto/fedora.conf
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = lxcbr0
lxc.network.ipv4 =
lxc.network.name = eth0
lxc.cgroup.cpu.shares = 512
lxc.cgroup.memory.limit_in_bytes = 1024M
lxc.cgroup.memory.memsw.limit_in_bytes = 3072M

But we might need something first

root@lxc-host:~# apt-get install yum

The actual lxc-create syntax

root@lxc-host:~# lxc-create -n fedora-guest -t fedora -f /etc/lxc/auto/fedora.conf 
root@lxc-host:~# vim /var/lib/lxc/fedora-guest/rootfs/etc/sysconfig/network-scripts/ifcfg-eth0
root@lxc-host:~# screen -dmS init-fedora-guest lxc-start -n fedora-guest
root@lxc-host:~# screen -ls
There is a screen on:
	19959.init-fedora-guest	(06/06/2012 09:55:39 AM)	(Detached)

And voila! I’ll admit this fedora install seems somewhat messed up, but that’s a problem with the template itself. You can correct the install or use something else like ubuntu/ubuntu-cloud for better results. Let me know if you have questions.

iSCSI performance in the cloud

This is one of the more entertaining things I’ve done at work and according to the emails i received from co-workers one of the most controversial. Someone asked if this could be done, and i figured i’d give it a shot. This will be in two parts, the first being FileIO since I was having problems trying to get partition re-sizes to work in the cloud. Part two will be BlockIO once I get around to fixing the kernels.

I used CentOS 6 for all of the servers involved in this setup and all network traffic is over the internal service network.

[root@vsan1 ~]# dd if=/dev/zero of=/root/block.img bs=4M count=1250

The other iSCSI drive is a RAID 0 configuration using a much smaller block size for comparison.

[root@vsan2 ~]# dd if=/dev/zero of=/root/block.img bs=512K count=30720 
[root@vsan3 ~]# dd if=/dev/zero of=/root/block.img bs=512K count=30720
[root@master ~]# mdadm -Cv /dev/md0 -l0 -n2 -c128 /dev/sdb1 /dev/sdc1

All of the targets are setup the same way:

Target iqn.2012-03.local.node:vsan2 
Lun 0 Path=/root/block.img,Type=fileio,IOMode=wb 
Alias vsan2 
ImmediateData Yes 
MaxConnections 2 
InitialR2T No

I’m just using hdparm for basic tests. I wasn’t really inspired to test further. For comparison here is the actual block device offered by xenserver:

[root@master ~]# hdparm -tT /dev/xvda 
Timing cached reads: 1948 MB in 1.99 seconds = 977.19 MB/sec 
Timing buffered disk reads: 82 MB in 3.10 seconds = 26.45 MB/sec

That is actually lower than what I received before during my tests, but it’s what I got when writing this response. Now to test the single drive, 4M block size device:

[root@master ~]# hdparm -tT /dev/sda 
Timing cached reads: 1696 MB in 1.99 seconds = 850.29 MB/sec 
Timing buffered disk reads: 16 MB in 3.40 seconds = 4.71 MB/sec

And finally for the RAID0 performance results:

[root@master ~]# hdparm -tT /dev/md0 
Timing cached reads: 1968 MB in 1.99 seconds = 987.01 MB/sec 
Timing buffered disk reads: 28 MB in 3.04 seconds = 9.21 MB/sec

Kinda meh results, but that’s what you can expect from fileio. I’m really looking forward to the blockio tests, but the kernels on the gentoo images are 3.0+ and I need 2.6+ for iscsi to work. When I get around to it i’ll finish setting that up.