Red Hat focuses enterprise efforts with Advanced Server 3.0

It's been quite some time since Red Hat refreshed its enterprise server line, and the Linux world has changed significantly since Red Hat released Advanced Server 2.1 nearly 18 months ago.

A longer release cycle is generally seen as a benefit to enterprise server operating systems, as it eases the burden of trying to develop applications on an OS layer that's continually changing and provides the vendor with more time to work out the kinks in the next release. This time, it’s worth the wait. Red Hat has taken its time, updated myriad supporting packages, and produced a hardened, solid OS in Red Hat AS 3.0.

Upgrades Galore

There are significant core changes in AS 3.0, such as x86 support for up to 16 CPUs and 64GB of RAM (AS 2.1 was limited to eight CPUs and 16GB of RAM). The stock kernel update from 2.4.9 to 2.4.21 and the GCC (GNU Compiler Collection) update from 2.9.6 to 3.2 are very welcome indeed. The less overt changes are key, however, especially NPTL (Native Posix Threading Library) integration, the inclusion of a hyperthreading scheduler, and the presence of LVM (Logical Volume Manager).

The Red Hat-designed NPTL is a significant change over the previous use of LinuxThreads, one that can mean dramatically increased performance for multithreading applications. The 2.4.21 kernel shipped with AS 3.0 is far from vanilla, incorporating several advanced features from the development 2.5 kernel tree such as the aforementioned NPTL support and integrated IPSec. Red Hat has also included AS 2.1 compatibility libraries to ease application integration during the upgrade process.

The addition of extended attributes and ACL (Access Control Lists) support at the kernel level -- plus the addition of the required ACL control applications -- make the implementation of Windows NT-style ACL file permissions much simpler. This in turn makes the integration of Samba 3.0 into a Microsoft network much easier, and with ACL support administrators can finally stop the manual kernel reconfiguration they were forced to do in previous distributions.

Another significant change is the AS line’s support for AMD's Opteron 64-bit processor, building on AS 2.1’s support for Itanium and x86. (AS 3.0 also supports IBM's zSeries, iSeries, pSeries, and S/390 architectures.) I tested the x86, AMD, and Itanium releases: The x86 and Itanium builds installed and functioned without issue, but the AMD 64 build wasn’t quite as simple.

I used new 2.2GHz AMD Opteron 248 CPUs, but the default SMP (symmetric multiprocessing) kernel wouldn't boot -- yet the uniprocessor kernel did. Compilation of several 2.4 branch kernels also exhibited this behavior, and an installation of SuSE SLES (SuSE Linux Enterprise Server) experienced the same behavior. I determined the issue is related to a bug in the mainboard BIOS of my reference system. Passing idle=poll to the kernel at boot permits the Red Hat 2.4.21ELsmp kernel to boot but forces the kernel’s idle loop to poll on the Need Reschedule flag, rather than waiting for an interrupt, which can result in performance degradation under some workloads.

On the service front, Red Hat updated Samba to the current Version 3.0 and included Apache 2.0.46 with some custom tweaks and improvements in scalability and application delivery far beyond the Apache 1.x version. Samba 3.0 includes support for full Windows 2000 integration. Prior to 3.0, Samba would integrate into an AD (Active Directory) network emulating a Windows NT server, relying on NetBIOS. With Samba 3.0, a Samba server can fully participate in an AD network, masquerading as a Windows 2000 server to Windows clients.