Compare Linux and Windows 2000

FreeBSD vs. Linux vs. Windows 2000

FreeBSD Linux Windows 2000

Reliability FreeBSD is extremely robust. There are numerous testimonials of active servers with uptimes measured in years. The new Soft Updates1 file system optimizes disk I/O for high performance, yet still ensures reliability for transaction based applications, such as databases. Linux is well known for its reliability. Servers often stay up for years. However, disk I/O is non-synchronous by default, which is less reliable for transaction based operations, and can produce a corrupted filesystem after a system crash or power failure. But for the average user, Linux is a very dependable OS. All Windows users are familiar with the "Blue Screen of Death". Poor reliability is one of the major drawbacks of Windows. Some of the major issues have been fixed in Windows 2000, but "code bloat" has introduced many more reliability problems. Windows 2000 uses a lot of system resources and it is very difficult to keep the system up for more than a couple of months without it reverting to a crawl as memory gets corrupted and filesystems fragmented.

Performance FreeBSD is the system of choice for high performance network applications. FreeBSD will outperform other systems when running on equivalent hardware. The largest and busiest public server on the Internet, at ftp.freesoftware.com, uses FreeBSD to serve more than 1.2TB/day of downloads. FreeBSD is used by Yahoo!, Qwest and many others as their main server OS because of its ability to handle heavy network traffic with high performance and rock solid reliability. Linux performs well for most applications, however the performance is not optimal under heavy network load. The network performance of Linux is 20-30% below the capacity of FreeBSD running on the same hardware 2. The situation has improved somewhat recently and the 2.4 release of the Linux kernel will introduce a new virutual memory system based on the same concepts as the FreeBSD VM system. Since both operating systems are open source, beneficial technologies are shared and for this reason the performance of Linux and FreeBSD is rapidly converging. Windows is adequate for routine desktop apps, but it is unable to handle heavy network loads. A few organizations try to make it work as an Internet server. For instance, barnesandnoble.com uses Windows-NT, as can be verifyed by the error messages that their webserver produces, such as this recent example: Error Message: [Microsoft][ODBC SQL Server Driver][SQL Server]Can't allocate space for object 'queryHistory' in database 'web' because the 'default' segment is full.

For their own "Hotmail" Internet servers, Microsoft used FreeBSD for many years.

Security

FreeBSD has been the subject of a massive auditing project for several years. All of the critical system components have been checked and rechecked for security-related errors. The entire system is open source so the security of the system can and has been verified by third parties. A default FreeBSD installation has yet to be affected by a single CERT security advisory in 2000.3

FreeBSD also has the notion of kernel security levels. These are much more powerful than simple run-levels since they allow the administrator to completely deny access to certain operating system functions such as reading /dev/mem, changing file system flags, or writing to disks without mounting a filesystem.

FreeBSD includes a very robust packet filtering firewall system and many intrusion detection tools.

The open source nature of Linux allows anyone to inspect the security of the code and make changes, but in reality the Linux codebase is modified too rapidly by inexperienced programmers. There is no formal code review policy and for this reason Linux has been suceptible to nearly every Unix-based CERT advisory of the year. This problem is compounded by the fact that distributions like Red Hat tend to turn on notoriously insecure services by default.

However, Linux does include a very robust packet filtering firewall system and many intrusion detection tools.

Microsoft claims that their products are secure. But they offer no guarantee, and their software is not available for inspection or peer review. Since Windows is closed source there is no way for users to fix or diagnose any of the security compromises that are regularly published about Microsoft systems.

Filesystem

FreeBSD uses the UFS (Unix File System), which is a little more complex than Linux's ext2. It offers a better way to insure filesystem data integrity, mainly with the "sofupdates" option. This option decreases synchronous I/O and increases asynchronous I/O because writes to a UFS filesystem aren't synced on a sector basis but according to the filesystem structure. This ensures that the filesystem is always coherent between two updates.

The FreeBSD filesystem also supports file flags, which can stop a would-be intruder dead in his or her tracks. There are several flags that you can add to a file such as the immutable flag. The immutable (schg) flag won't allow any alteration to the file or directory unless you remove it. Other very handy flags are append only (sappnd), cannot delete (sunlnk), and archive (arch). When you combine these with the kernel security level option, you have a very impenetrable system.

The Linux ext2 filesystem gets its performance from having an asynchronous mount. You can mount FreeBSD UFS filesystems as asynchronous but this is very dangerous and no seasoned Unix admin would do this. It's amazing that Linux is designed this way by default. Often a hard carsh permanently damages a mount. FreeBSD or Solaris can sustain a very hard crash with only minor data loss, and the filesystem will be remountable with few problems.

There are several new journaling filesystems in development for Linux that will fix some of these issues, but these will not be ready for the 2.4 release of Linux.

The Microsoft FAT filesystem and the newer NTFS are both plagued by over 15 years of backwards compatibility

with the earliest of PC-based filesystems. These filesystems were not designed for today's demanding server applications, they weren't even designed with a multi-user OS or networking in mind!