The enterprise environment and the new Linux 2.4 kernel

[Bruce F Lucca]

Linux 2.4 is enterprise-ready
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Don't look now, but Linux 2.4 is enterprise-ready

Feb 13, 2001
Jason Hiner
(C) 2001 TechRepublic, Inc.

The long-awaited Linux 2.4 kernel has finally made its appearance?and it
has given the operating system a lot more ammunition in its server war
against Novell Netware, Microsoft Windows NT/2000, and commercial UNIX
vendors such as Sun Microsystems. The 2.4 kernel systematically addresses
and remedies the main weakness that has kept Linux from winning more
servers in the enterprise: scalability. Let's compare Linux to the network
operating systems that currently dominate the enterprise. Table A shows how
they stack up.

Table A
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Improvements
The changes in Linux 2.4 deal mainly with the internal infrastructure that
governs how the OS gets things done. 

The most notable improvements occur in the following areas:

- Optimization for symmetrical multiprocessing (SMP)
- Support for up to 64 gigabytes of RAM
- Rewritten network layer for better performance and throughput
- Expanded hardware support
- Support for a large number of users and for larger file sizes

With the 2.2 kernel, Linux's most acute enterprise problems were in the
area of SMP. Although Linux 2.2 technically supported SMP up to four
processors, the additional processors did not help Linux get things done
any faster, and the OS's internal dealings with multiple processors were
clunky at best. In other words, Linux 2.2 was not optimized for SMP, a
necessity for enterprise environments.

The 2.4 kernel has effectively removed this obstacle. Linux 2.4 is well
optimized and tested on SMP machines with up to eight processors. There
have even been reports of development and deployment teams using the kernel
on SMP machines with anywhere from 32 to 64 processors. Officially, the
number of processors supported by Linux 2.4 is still eight but look for
this number to expand with further testing in the coming months.

Another SMP-related Linux 2.4 improvement is support for multiple Advanced
Programming Interrupt Controllers (APICs). These I/O controllers are used
in SMP to spread the load for processing interrupt requests among the
various CPUs, thus allowing for faster and better use of multiprocessing.
Memory support had been another Linux drawback. Enterprise servers,
especially database servers, require very large amounts of RAM, and Linux
2.2 was limited to 2 gigabytes. With the 2.4 kernel, Linux now supports up
to 64 gigabytes.

Benchmarks such as the one done by Mindcraft a couple years ago showed that
the Linux 2.2 kernel also had some networking limitations. As a result,
Linux developers completely rewrote the networking layer for the 2.4 kernel
to better handle multi-threading and thus improve the networking speed and
efficiency of the kernel.

The expanded hardware support of the Linux 2.4 kernel will also have
implications for the enterprise. Linux 2.4 can support up to 10 IDE
controllers, up to 20 hard disks, and up to 16 network cards. (Linux 2.2
did not handle multiple network cards very well.) Linux 2.4 also improves
RAID support and performance, another key for enterprise SMP servers.
Additionally, the kernel has been expanded to support the Intel 64-bit
Itanium processor and the IBM S/390 mainframe.

In terms of storage, the 2.4 kernel contains support for Logical Volume
Management (LVM), which enables administrators to manage and make changes
to storage systems while they are live. Obviously, this is very important
in a 24/7 enterprise environment, and this feature has been a mainstay of
other UNIX-based enterprise operating systems.

Another key in making Linux ready for the enterprise was addressing
limitations in file size and volume of users and groups. In Linux 2.2, file
size was limited to 2 gigabytes, and the number of user and group objects
was limited to 65,563. Linux 2.4 allows up to 1-terabyte files and up to
4.2 billion user and group objects.

Additional 2.4 kernel enhancements include faster I/O between the kernel
and peripherals, support for NFS version 3 (which boasts increased
performance and stability), support for ISA Plug and Play cards, built-in
kernel Web daemon (kHTTP), which will increase performance in serving
static Web pages and will integrate with Apache, and PPP support for DSL
and ATM.

Measuring up 
So how does Linux now measure up against its enterprise competitors, such
as Novell, Microsoft, and Sun? Well, the big boys definitely have reason
for concern. Linux 2.4 matches, and in some areas exceeds, the enterprise
capabilities of its competitors. Let's compare Linux with some of the other
enterprise products.

Despite its steep decline in recent years, Novell Netware still makes its
home on a lot of enterprise servers. Windows NT stole nearly all of the
small and midsize business accounts from Novell, but NT's scalability
problems kept it out of most enterprise shops, at least as the network
backbone. 

However, NetWare is still a very expensive product. And with Novell's PR
problems and Linux matching it feature for feature for a lot less money,
NetWare could be in trouble.

Linux even beats NetWare in some categories. NetWare 5.1 currently supports
up to 32 processors and 4 gigabytes of RAM. Linux 2.4 would clearly have
much more strength running an enterprise database server because of its RAM
capacity. However, NetWare's saving grace may be its popular directory
services -=- NDS -=- which Novell has been rumored to be marketing to Linux
vendors, such as Red Hat.

When all is said and done, Novell may end up becoming a Linux ally.

With the release of Windows 2000, Microsoft is trying to do much of what
Linux is attempting with the 2.4 kernel -=- win more enterprise servers.
With Active Directory and Windows 2000 Datacenter, Microsoft has greatly
increased the scalability of Windows servers. Windows NT 4.0 Enterprise
Edition could handle up to eight processors and 4 gigabytes of RAM. Win2K
Datacenter supports up to 32 processors and 64 gigabytes of RAM.

However, Win2K Datacenter is still an immature product, and it doesn't have
much Windows software that natively scales up to enterprise capacity.
Linux, on the other hand, benefits from binary compatibility with the many
UNIX-based applications that have developed and matured over the years. 

All things considered, at this point Linux 2.4 will be better prepared to
win enterprise server space than Windows 2000 Datacenter. Nevertheless,
with the pending advent of Microsoft .NET and the company's venerable
marketing muscle, Windows could still make some major enterprise gains.
Look for Windows and Linux to battle each other fiercely for enterprise
space in the coming years.

Before we get too wrapped up in the coming Linux vs. Windows war, let's not
forget about "the dot in dot com." Sun Microsystems' Solaris operating
system is currently the gold standard for enterprise servers. It scales up
to 64 processors and 64 gigabytes of memory, and it has pulled ahead of its
UNIX competitors from IBM, HP, Compaq, and others in recent years as the
leader in high-end enterprise servers. 

Sun has formed a somewhat tenuous relationship with Linux vendors, mostly
to help develop standards for UNIX and Linux desktops that can battle
Microsoft on that front. They need to keep an eye on Linux so that it
doesn't take too big a share of new enterprise contracts, but don't look
for many companies to scrap their current Solaris environment for Linux any
time soon.

When it comes down to it, Linux's best chance of making serious headway in
the enterprise may rest with Big Blue. IBM has been investing heavily in
Linux in recent years, and they have well established relationships with
many large organizations. 

Enterprises like to buy hardware and software in a package deal from one
vendor, especially when they are buying a UNIX OS. HP, Sun and IBM have
been very successful in marketing their hardware/software packages to
enterprise customers. With the arrival of the 2.4 kernel, watch for IBM to
leverage its Linux investments to make a strong play for new enterprise
contracts with robust and well-priced enterprise servers based on Linux.
Other companies, such as HP and Compaq, may follow suit.

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editor an e-mail.

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