An analysis by D.H. Brown Associates ranked SuSE's version 7.2 at the top of the heap, with a "good" rating. Red Hat 7.1 was a notch behind, but still earning a "good." Caldera International's OpenLinux 3.1 and Turbolinux Server 6.5 managed only "above average," but still ranked better than Caldera's UnixWare, the study found.
The study evaluates features and performance in dozens of areas, such as support for multiprocessor systems and large files.
The results reflect the gradual rise of Linux, a clone of Unix that has won a place in the product plans of IBM, Oracle, SAP, Intel and other computing giants. In an earlier version of the same study two years ago, when Linux was just finding mainstream support, D.H. Brown found several weaknesses
"There are a lot of holes that have been filled in," said Tony Iams, an author of the study. "It's a noticeable improvement from a couple years ago."
Sun Microsystems' Solaris version of Unix, the top-ranked operating system in the study, was well ahead of the Linux versions with a "very good" ranking. The study didn't include Microsoft Windows, which includes as an essential part several higher-level software features that make straight comparisons difficult, Iams said.
The new version 2.4 of the Linux kernel, or core software, has boosted the operating system a notch, the study found. The new kernel is able to take advantage of all the CPUs on an eight-processor system, the study said, helped in part by completely rewritten networking software.
However, only Red Hat surpassed UnixWare in scalability, edging past Linux competitors by virtue of having published benchmarks, the study said.
Several low-level improvements to Linux in the works should boost it further, the study said. Among them are "raw I/O," which lets the operating system write information directly to disk while bypassing the file system usually used to organize the information on the disk, and "asynchronous I/O," which lets the operating system conduct several jobs reading and writing information simultaneously instead of waiting for the first to finish before the next one can start. SGI is working on adding both these technologies to Linux.
However, there still is a lot of work to be done. In one D.H. Brown category measuring "reliability, availability and serviceability," UnixWare and others are well ahead of Linux.
"Commercial Unix systems support far more advanced RAS features than any current Linux systems. Even SuSE, the Linux leader in this area, falls well behind the weakest Unix system," the report said.
Several companies--including SuSE, SteelEye, Turbolinux, Red Hat and Mission Critical Linux--are working on high-availability "clustering" software that lets one server take over for a crashed comrade. However, "True high-availability clustering options for Linux remain in their infancy," the study said.
The study also found shortcomings for managing Linux systems.
Compensating, though, were high marks for how well Linux conducted Web and Internet operations. In particular, Red Hat achieved a "very good" ranking in this category.
In addition, Red Hat and SuSE both achieved "very good" ranking in support for security software and hardware and directory software that makes administration easier.