The discussion comparing Linux/{Intel/Sun/HP/IBM/Mac} Sun/Solaris may be interesting, but it boils down to what you need in a server and who delivers it. There can be and are mission critical applications being run on Linux machines every day. We have precedence of this happening on a wide spread basis. Depending upon what you wish to run, and who supports the desired software and hardware, you will have to make your choice between Linux or some other "commercial-grade" UNIX. Remember, the commercial UNIX'es have 20+ years of reputation over Linux, an infant to the POSIX OS world. UNIX is and will be the champion of many a Sysadmin for many years to come. The Intel architecture itself was never intended for servers in the first place. It was a fairly recent phenomenon, relatively speaking, to see Intel servers dominate the business networks. We largely have Microsoft to blame/praise for this in making their Windows operating systems accessible at a low-cost entry. Investing in a $5000 Intel server made and continues to make accountants much happier than investing in a $50,000 server. Still, the Intel platform can perform well under many applications. The term "mission critical" itself is misleading. Factory device/machine controllers are far different mission critical operations than RDBMS transactions or packet routing. The versatility of Linux in that it can operate well in any of these jobs makes it quite attractive. Especially when you consider it's current state of portability. Still, if your production line vendor only supports Sun device drivers and management software, guess what you'll be using. Would I use Linux for "mission critical" applications? Certainly. I've worked with multiple business that have successfully deployed very dependable Linux environments. Is it the right solution for every problem domain? Absolutely not. Why? "When you have a hammer, everything looks like a nail." -- Chad Walstrom <chewie at wookimus.net> | a.k.a. ^chewie http://www.wookimus.net/ | s.k.a. gunnarr Key fingerprint = B4AB D627 9CBD 687E 7A31 1950 0CC7 0B18 206C 5AFD