
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