Monthly Archives: June 2013

Understanding Libvirt and APIs For VMware Professionals

As discussed in my previous post, Libvirt is an open source project for managing hypervisors. With the increasing popularity of Openstack, it’s important to get familiar with KVM as an alternative virtualization platform to commercial products like vSphere and Hyper-V.

To use KVM, you don’t have to install Openstack – you can just install KVM as a standalone product as described in my previous post. In that, it’s pretty much like VMware Player or Workstation. In terms of maturity, KVM is pretty solid and way ahead of Openstack which is also improving quickly since last year with many commercial vendors jumping in.

Posted in Virtualization | Tagged , , , , | 1 Response

KVM or QEMU: Which Runs My Virtual Machine?

While working with Openstack on both VMware virtual machines (with no virtualization instruction set exposed) and physical machines, I found virtual machine instances can be deployed seamlessly. On a machine that does not have virtualization instruction set exposed, KVM falls back to QEMU silently. That is why could I try out OpenStack on virtual machines before my hardware was ready. Because both KVM and QEMU support the same libvirt APIs, you would not notice any difference using command line like virsh, or Virtualization Manager. That is the beauty of standard APIs with different implementations, similar to the standard vSphere APIs that are implemented by both vCenter and ESXi.

Posted in Virtualization | Tagged , , , | 2 Responses

Managing KVM with Libvirt In Java: Step by Step Tutorial

As mentioned earlier, I got the KVM instances running on my compute cluster after installing the Openstack. I’ve been curious on KVM management APIs, so I took some time to give it a try. In the following, I’ll detail on how to set up environment and get your first HelloWorld type of Java code working.

Posted in Virtualization | Tagged , , | 9 Responses

Virsh Commands: Why They Are Important

After installing Openstack, I got KVM/QEMU installed as a by-product. To get myself familiar with the functionalities, I played with Virtulization Manager and the virsh command line. By comparing with the libvirt API, I found they are pretty similar. Therefore, I think it’s a good starting point before jumping to the APIs. Also, the virsh is implemented on top of the libvirt APIs.

Posted in Virtualization | Tagged , , | 1 Response

Slow SSH Client and Quick Hack

While using PackStack to install OpenStack for multi-node topology, I found my SSH client was so slow that it failed the PackStack installation command. The ssh I had was the default one with CentOS 6.4: “OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010.” It seemed to work just fine while using PackStack for all-in-one deployment as described in my previous article.

To isolate the problem, I started to print more debug information from the SSH as follows:

Posted in Cloud Computing | Tagged , | 4 Responses

Installing OpenStack With Multiple Nodes: Tips and Tricks

Having successfully installed OpenStack all-in-one with PackStack, I started to try out the multi-node deployment. It ended up much longer time than I thought because of various issues mainly with networking. The following summarizes what I did to make it work, and some tricks and tips I found out during the process.

Posted in Cloud Computing | Tagged , , | 5 Responses

Tip For Tech Bloggers: Easy Way to Document Command History

While writing technical blogs, it’s always nice to include commands and scripts that readers can try on their own. I find it a bit challenging to accurately document these in steps while intensively testing or debugging something by myself.

There are actually commands that faithfully list all the commands you typed. You can then clean them up for your posts. In the following, I introduce how to do these on Linux, Windows.

Linux

Posted in Software Development | Tagged , | 1 Response

WebStocket in HTML5: Time to Give it a Try

WebSocket is a new technology that is part of HTML5. It allows a browser (or an application that uses HTTP/HTTPS) to upgrade a HTTP/HTTPS connection to a full socket to the server so that both parties can send data at any time.

WebSocket Standard

The WebSocket protocol is defined in RFC 6455. The initial handshaking is a HTTP request with upgrade header like the following from the RFC:

GET /chat HTTP/1.1

Host: server.example.com

Posted in Software Development | Tagged , , | 2 Responses
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