These tests shouldn't be considered conclusive or the final matter on the performance of both systems by any means, especially considering the complicated nature of performance assessment in general, and the limited equipment (and time) I had with which to conduct the tests.
That said, I can make a few conclusions. Performance was overall similar for most of the metrics tested, perhaps with Linux in a very slight lead. However, with the web operations test (arguably the most important and relevant), Linux is a clear winner.
I didn't have the opportunity (or means) to test Java performance on both systems, for both Apache/Tomcat and pure Java. Also, pitting IBM's Java on Linux versus Sun's Java on Solaris would have made for a fascinating competition.
Hardware Support
On the subject of hardware support, Linux wins. Virtually any common device (such as IDE RAID controllers, server motherboards, Fast/Gig Ethernet cards) has a production-quality open source driver, usually distributed with the Linux distribution (and works out of the box) or the vendor has compiled and made a driver available as a module.
For more specialized hardware, vendors commonly release their own Linux binary drivers in cases where open source drivers may not be available, meaning Linux is taken very seriously in the Enterprise.
That is not the case with Solaris x86. While I had no problem installing on my system, there are many systems in which Solaris x86 will not run because of one or more missing drivers. This is just a symptom of Sun's previous lack of interest in Solaris x86 development, and a lack of open source community support that gives Linux it's wide driver base.
Before considering Solaris x86, make sure to take a look at their HCL (Hardware Compatibility List available at http://www.sun.com/bigadmin/hcl/) to see if your hardware will even support it.
Cost
Cost is always a consideration when evaluating any technology, and this is certainly no exception. Sun is, of course, a commercial and proprietary operating system. To use it commercially, you have to pay $100 USD for a single processor, $250 for a dual box, and $1,500 USD for a 4-way box. Educational and evaluation use is free, as long as you register, and as long as it's only a single CPU box. Those prices only for licensing, however. Support is an additional (and substantial) cost. In fact, it's possible that installing Solaris x86 on my dual-processor box, even if I disabled one of the processors, violates the evaluation license that Sun offers Solaris x86. Oops. Something to keep in mind is that Sun's licensing is akin to the Oracle per-CPU licensing, they refer to the capacity of the system, not just how many processors are actually there. A box capable of 2 processors with only one processor installed is still a dual-processor box in their eyes, license-compliance wise).Linux distributions, of course, can range from free (if you download an ISO) to even more than what Sun is asking for Solaris x86, such as RedHat's Enterprise Linux lists for $1499 for Standard Edition and $2499 for Enterprise Edition. Both editions support up to 16 processors (Solaris x86 supports up to 4 CPUs).
The pricing differences can vary greatly depending on your situation. With all the commercial applications included with Solaris x86, including Sun Screen firewall, Sun ONE Application Server, Volume Manager, and Sun ONE Directory server, it certainly has a value proposition. However, Linux has the advantage in flexibility in that you can either pay for your system or not. Building out a grid cluster of 100 machines can cost you zero dollars in licensing fees. As far as value is concerned, I have to say Linux is the clear winner, simply because it's free. You can pay for Linux and support if you want, but if you'd rather use effort instead of cash (which many companies that are strapped for cash are doing) then that's an option. With Linux, you don't have to worry about licensing fees associated with expanding your infrastructure.Conclusion
Ironically, Solaris x86 is now where Linux was 4 years ago: Great for open-source applications and on a limited set of hardware, but commercial enterprise applications are few and far between. If you're looking to run PHP, or Apache/Tomcat/Java (which comes pre-installed), then Solaris x86 is a solid, stable platform. But so is Linux. If you're looking to run any type of commercial applications, including several enterprise databases and even commercial backup applications, Linux is the clear choice.There are several issues facing Solaris x86 adoption. Sun's past history of neglect, lack of commercial applications, poor hardware support, and poor security support, all contribute to Solaris x86's lack of significant momentum towards adoption.
For this evaluation, I am inclined to declare Linux the clear winner over Solaris x86. Linux is simply better supported, shows double the web performance, enjoys wider internal development in terms of hardware and kernel, vastly wider application development, and is a better value (since it's, you know, free).
Solaris x86 isn't that far off though. It is an impressive operating system on its own right and if Sun stops spending time disparaging Linux and open source in general, I can easily see Solaris x86 making a broad and positive contribution to the market. The ball is in Sun's court.
