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Amazon AWS vs. RackSpace Cloud Windows 2008 I/O Test

I did a basic test trying to measure the un-tuned out-of-the-box I/O performance of Rackspace Cloud instance with the HDTune utility on a Windows Server 2008 instance. According the the RS documentation their disks are local RAID10. Then I run the same utility on 8 core extra large  EBS backed EC2 instance provided by Amazon (wanted to make sure it is not an issue due to a small EC2 instance size). According to the docs EBS should provide consistent performance of a SAN regardless of the instance type.

Here are the somehow surprising results. I was expecting, that they perform somehow equal but RS is in the range of 300 MB/s whereas the EC2 instance is below 40 MB/s.

Rackspace Cloud with Windows 2008:

AWS with Windows 2008:

Interesting enough also the CPU usage is quite different: 2% only for AWS and 31% for RS.

I welcome any comments and I am aware that the tool is meant to measure disks and not RAID or SAN volumes. Still I am surprised by the huge difference. I wonder if the difference is only due to the difference of local RAID vs. SAN. Also I wonder how is the SAN attached then, since the SAN performance is still worse than my laptop disk.

WebLogic Whole-Server Migration on EC2 Cloud?

WebLogic whole-server migration is a compelling solution for the availability of servers and pinned resources such as JMS  on those servers. It simply moves the IP address to the new candidate machine before starting the managed server there. From the perspective of the managed server there is no change at all, since even the IP address is the same. The crucial point however is the availability of floating IP addresses that can be automatically reassigned by the script.

On EC2 there are only two IP addresses per instance, a public and a private one. You cannot get additional IP addresses, so whole-server migration isn’t of much use.

In fact, you could get an elastic IP address, which is a reassignable, static IP address assigned to an EC instance. Still an elastic IP is not useful for server-migration because assignment of the address requires the EC2 command-line and cannot be done directly from the cluster script using ifconfig.

This text is a digest of my upcoming book about cloud computing with Oracle.

How to Connect to the Cloud

Quite often I chat with customers about cloud computing and tell them they could have a server running in the cloud for as little as 1 cent per hour.  Then their next question is: “Well, if it is running in the cloud, how can I access it then?“.

There seems to be a lot of confusion about it. Just because your server is running in the cloud, doesn’t mean it is not tangible. So the short answer is: “Use ssh and connect to it.“. Your server is not hidden in a nebula – it’s fully connected to the internet (at a fantastic bandwidth, a WebLogic 10.3.2 package download is completed in 4 mins at 3.8 MB/s) . For Amazon’s AWS you typically have to provide a X.509 certificate and RackspaceCloud uses password for root login with ssh.

Windows Options

Even if your managing the cloud from your Windows desktop you are not out of luck connecting to a UNIX server in the cloud, there are a couple of options:

  • There a free version of VNC for private and commercial use which is called TightVNC, see
  • NX is a desktop virtualization solution from a company called NoMachine. NoMachine designed the NX libraries to provide a self-tuning protocol with compression and reduced round-trips for X11 even over slow connections. Have a look at their homepage under They provide a free version which is limited to two connections only.
  • FreeNX was created in 2004 as the first complete free and GPLed server implementation of NX, see
  • Cygwin is another solution, see It provides a UNIX environment for Windows and comes with a X-server that can display your X based applications on your UNIX host. The software was written by Cygnus Solutions which now belongs to Red Hat.