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The commercial version of the Citrix XenServer does not allow you to choose the type of ethernet adapter to emulate within your VM. The standard device that is emulated is a Realtek 8139 (RTL8139), which is a 100Mbit/sec Fast Ethernet card.
Citrix themselves do not view this as a major issue, as they expect you to install paravirtualised drivers within your guest operating system. This is usually a very good idea and just fine if you're using Windows, or a major supported OS such as Red Hat, CentOS or Ubuntu. Under these Linux operating systems, your entire kernel must be replaced by a Citrix supplied kernel. The paravirtualised drivers will outperform any emulated device.
However, if you're running a system with a customised non-standard kernel that doesn't support Citrix Xen paravirtualisation, you'll be stuck with a 100Mbit/sec bottleneck in your network. Sure, you can go and rebuild your kernel with the right paravirtualised drivers, but that's not always an option.
Those familiar with the open source version of Xen will know that the underlying QEMU device emulation that Xen uses can emulate an Intel 1Gbit/sec adapter, called "e1000". Apart of the additional speed, this device also supports jumbo ethernet frames. This emulation mode is available under Citrix XenServer, but is a hidden feature, due to hard-coding of the Realtek driver option.
The open-source movement continues as Citrix announces its intention to release binaries and source code to the public. The XenServer open-source cloud will give programmers and hobbyists a way to tinker with a cloud server's capabilities and hopefully add to its security, functionality, and overall scalability.
Citrix and the Cloud
Most people have heard of Amazon Web Services (AWS) and Rackspaces' OpenStack cloud, but, according to ZDNet, what most people don't know is that CitrixXenServers are the backbone of their architecture. Citrix also supports and donates its software to the Apache Software Foundation, and it put its core Xenserver project under the Linux Foundation's control.
This move is especially good for midsize businesses that host Linux, Apache, MySQL, and PHP (LAMP) technologies on their network. With open-source software, a business can customize its internal software layer, or IT managers can contribute to the increasing open-source knowledge base. Included in the Citrix move is hosted bug tracking and a list of developers who contribute to the project.
How Open-Source Benefits Technology
Open-source is rapidly becoming a way for developers, hobbyists, and professionals to contribute to the overall betterment of software. Midsize businesses profit from these projects because the software is free. The increase in changes that result from mulitple developers can improve the product's security and functionality. Linux has long been an open-source project, and it has slowly become more popular than its rival, Microsoft Windows. Some companies have adopted Linux as their desktop operating software, and others are utilizing the flexibility of Linux-based networks with the usability of these Windows desktops.
Citrix's move also means customers currently running XenServer technology will have a change in contracts. Open-source is free to install, customize, and update for midsize businesses. However, open-source companies make money on support contracts. Each time the company needs support for an issue, a charge is made. Alternatively, the company can buy a support contract for the year. This is unlike paid software, such as Windows, that charge on an individual support incident basis.
While things might be bumpy for Citrix as it moves toward an open-source platform, the move benefits businesses and individuals who use cloud services. It also makes it more affordable for companies to get started with cloud computing and the advantages this technology has to offer. Unlike paid software, open-source is the collaboration of many innovative developers for new product customizations.
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