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Could virtualization take advantage of the wave of
multicore processors now being offered? Sun Microsystems has developed
a technology, Logical Domains (LDoms), that can be used to dedicate
each core of a processor to running its own operating system.
When most people think of Suns virtualization,
they probably think of Sun Solaris Containers. With this form of
virtualization, a server runs a single instance of Solaris, which an
administrator could add additional virtual zones, each of which can run
additional operating system-based virtual environments.
Could virtualization take advantage of the wave of
multicore processors now being offered? Sun Microsystems has developed
a technology, Logical Domains (LDoms), that can be used to dedicate
each core of a processor to running its own operating system.
When most people think of Suns virtualization,
they probably think of Sun Solaris Containers. With this form of
virtualization, a server runs a single instance of Solaris, which an
administrator could add additional virtual zones, each of which can run
additional operating system-based virtual environments.
LDoms takes a different approach, one that in the right circumstances could be more efficient than the Containers approach.
Logical Domains is another form of
virtualization, said Harry Foxwell, a senior system engineer at Sun
Federal, in a presentation at last years Washington Open Solaris Users
Group meeting.
Sun started offering LDoms with OpenSolaris 10
build 61 and Solaris 10 11/06, to better harness its multicore,
multithreaded UltraSparc processors. The current UltraSparc T2 has
eight cores, and each core is capable of handling eight threads
simultaneously.
LDoms was designed to run a separate virtualized
environment with each thread. As a result, A single Sun UltraSparc
T2-based server can run as many as 64 virtualized instances.
Like the virtualization approaches from Advanced
Micro Devices and Intel, LDoms is based on hypervisor management, or a
thin layer of software that interacts with the hardware directly.
However, the LDoms hypervisor does not reside on the CPU. It resides in
the firmware of the machine.
Unlike Container Zones, each LDoms gets its own
operating system kernel. The administrator sets up a control domain
which can be used to manage the other domains, though each domain
interacts directly with the hardware, eliminating the middle layer of
software that slows performance in software-based virtualization
approaches.
There are a number of advantages to this approach,
Foxwell said. One is what he called complete CPU isolation. A heavy
load in a virtual environment will not hamper the performance of the
others.
Yet another benefit is a fine-grained flexibility
of resources. Administrators are not limited to dedicating only a
single thread to a single virtual environment.
Administrators can allocate multiple CPUs for each domain. They can
also shift resources among different domains on the fly.
You can shift back and forth the CPUs from one
domain to another, Foxwell said. If I make a mistake and
over-provision one and under-provision another, I can use the command
line or even a script to shift resources back and forth between the
two.
There are additional benefits for Sun shops, too.
Foxwell said Suns Network File System cannot run within a Container,
because it requires global control of the server itself. However, an
NFS file server can run within an LDoms.
LDoms supports virtualization of Solaris,
OpenSolaris and Ubuntu Linux. For more information on LDoms from Sun
Microsystems, see GCN QuickFind 891.
Read the original article: http://www.gcn.com/print/27_1/45651-1.html
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