Linux is a very robust operating system, designed from the ground up to handle multiple simultaneous processes. This multithreading allows Linux servers not only to handle many requests at the same time, but also to serve many different types of requests. It's not uncommon, especially in the appliance market, to have one server acting as a mail, Web, FTP (File Transfer Protocol), and file server.

For times when a single server is simply not going to be enough, Linux and Lotus offer several advanced features, such as load balancing and clustering that will allow you to grow the server with your business.

Linux limitations
There are some limitations to keep in mind when deciding if Linux is right for your organization. Many of these problems won't affect small to medium-size groups, but it's important to be aware of them if you're considering Linux for a larger enterprise.

Most of the scalability and performance issues with running Domino on Linux are determined by the limitations of the current release of the Linux kernel, not with Domino. Linux has a file size limitation of 2GB. This can create problems, especially when you consider that your Domino database may grow to that size someday. The current RAM limitation within Linux is also 2GB. While this may sound like a lot, 1GB of RAM is quickly becoming a standard in some industries.

While Linux supports up to 16 processors, it unfortunately has trouble scaling past a four-processor system. Other limitations include the number of threads/processes and file descriptors. The current release of the Linux kernel allows 256 processes and 1024 file descriptors per user. To put these limitations in perspective, a recent report by IBM at NotesBench (at http://www.notesbench.org) detailed that a Netfinity 5000 server with a Pentium III/500 MHZ and 1GB of RAM supports 800 concurrent Web Mail users.

Many of these issues are going to be addressed when version 2.4 of the Linux kernel is released. With this new version of the kernel, Domino for Linux will perform similarly to Domino on other platforms. As of this writing, the 2.4 kernel is very close to completion. Some of the new features of the kernel are: better scalability on multiprocessor systems; the ability to handle up to 64GB of RAM; an unrestricted file size; and support for up to 4.2 billion users.

Security
Since the majority of organizations use Linux on publicly accessible servers, security is an important issue. Linux has a lot of built-in security features, and because it's open source, you have the power to make it even more secure.

When you first install Linux (compile the kernel) you can select the types of applications you want to install. If you're creating a server with a specific purpose, you don't have to include programs you won't be using The fewer programs, the fewer potential security bugs.

Because Linux ties security to specific files, not the system, you have a lot more control just by locking down your file system. Not only are you able to set permissions down to the file level, you can also easily monitor logs to see how the file system has changed and to see what types of changes were made.