Nothing formal here, but while debugging a performance issue with the Sybase driver, I had a Sun E250 with 2 400MHz CPUs and 1GB RAM, and one generic Linux box with a 700MHz PIII and 512MB RAM. Both systems ran AOLserver 3.x; the Linux box ran a Sybase server using the Sybase 11.x server available for free from Sybase, while the Sun had an external Sybase server which was housed on an unknown machine (probably a mid-range SGI or HP box). The Linux box was able to query rows from the database approximately 4x faster than the Sun was, but it's possible the difference was network chatter between the Sun and its Sybase server or other causes. (Both systems used the local version of the Sybase proxy interface, so that wasn't the problem.) This was an isolated, artificial test, meant solely to get a bead on row fetch performance in the Sybase driver, and does not necessarily reflect overall performance, nor how gracefully the systems fail. It sure was interesting, though, to see such a wide margin of performance between the two systems.
One of the biggest issues in a "serious" production environment is that Sun will sell you a reasonably-priced service contract where you can call them as much as you like for issues, with no time limits on each issue, and no limit on the number of issues. You can't buy such contracts for Linux. Linuxcare is a popular Linux service vendor, and their plans basically boil down to $200/hour support unless you lean on them, and then the price will drop some, but you still face issue/time-per-issue limits. The Sun contract covers both hardware and software issues. It's possible to rationalize the Linux support situation by saying that, for the price, you can buy spares, and the Linux community is fairly good (although sometimes it can be harsh to poorly-phrased questions) at providing software support. I have a customer who won't consider Linux in production because he can't get "all-you-can-eat" support contracts for Linux. If this is important to you, it's worth consideration.
