Linux System Administration

High-Performance Computing

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characteristics. The 2.6 kernel fixed that problem and greatly expanded the number

of processors on which the kernel could run.

This is important for two reasons. First, as a host for virtual machines, Linux has to

perform well and excel at managing its hardware. Second, as a guest divorced from

its physical hardware, it has to maintain its performance and capacity to handle vari-

ous processes as the host. Today, Linux makes both a great host and a great guest

OS. It manages hardware and virtual partitioning and runs well in the guest parti-

tions, thanks to HP and IBM.

If you’ve ever wondered why companies like XenSource and Virtual Iron suddenly

appeared out of thin air, now you know: it’s because of open source hypervisor con-

tributions. Like the hardware vendors that realized Linux could enhance PC and data

center component sales, software vendors jumped on the bandwagon. Even

Microsoft eventually realized it needed to get in on the Linux game, contributing to

both XenSource and Virtual Iron.

Business Continuity and Workload Management

Even on a small scale, your organization will benefit from separating email, DNS,

and web servers and directories, gateways, and databases. Placing each of these ser-

vices on a unique server ensures that if one server goes down, your entire infrastruc-

ture doesn’t collapse. But separating your services on physical hardware