Come to my Cloud Computing Talk at DOAG 2010

Come to my Weblogic and Cloud Computing talk from 15:00h – 15:45h
in room Kopenhagen.

– Win a copy of my Oracle Cloud Computing Book!
– Learn how to use a computer in the cloud for one year for free!
– Understand WebLogic showstoppers in public clouds and design tradeoffs for clustering, JMS, load balancing, CDNs and databases.

Win a Copy of Middleware and Cloud Computing Book

If you are interested in Middleware and Cloud Computing subscribe to my my newsletter and win one of the first two copies of my brand new cloud computing book. The drawing will be Dec. 15th 2010.

There are only 4 mailings per year and you can unsubscribe any time from the newsletter.

Oracle Middleware and Cloud Computing Book

AWS Relational Database Service (RDS): Read Replicas & Multi-AZ Instances

Friday morning. Second cup of coffee. I remember the discussion I had yesterday about the differences of RDS read replicas vs. multi-AZ instances in the Amazon compute cloud.

Actually these concepts are completely different. So it is important to pick the right one that supports your design. Here is a short comparison:

Multi-availability zone instances Read replicas
Purpose Availability Scalability
Number of copies 1 primary + 1 secondary 1 primary + n secondaries
Secondaries used during normal operation? No Yes
Synchronization Synchronous Asynchronous
Use with ELB No (only one active) Not supported
Use with elastic IPs Not supported Not supported
Cost Doubles Per Instance

And don’t forget you can use a combination of both.

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 wlsifconfig.sh 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 http://www.tightvnc.com.
  • 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 http://www.nomachine.com. 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 http://freenx.berlios.de.
  • Cygwin is another solution, see http://www.cygwin.com. 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.