Introduction to Virtualization - Oracle Solaris 10 System Virtualization Essentials - page 31

1.2.1.6 Relative Strengths of Hardware Partitions
Hardware partitions offer the best isolation in the virtualization spectrum.
Whenever isolation is the most important factor, hardware partitions should be
considered.
Partitions are the only virtualization method that achieves native performance
and zero performance variability. Whether the workload is run in an eight-CPU
partition or an eight-CPU nonpartitioned system, the performance will be exactly
the same.
Partitions offer other advantages over other virtualization methods. Most no-
tably, few changes to data center processes are required: Operating systems are
installed and maintained in the same fashion as on non-virtualized systems.
1.2.1.7 Industry Examples
Several products offer excellent hardware isolation. This section provides a repre-
sentative list of examples.
The first server to use SPARC processors and Solaris to implement hard par-
titioning was the Cray CS6400, in 1993. Sun Microsystems included Dynamic
Domains on the Enterprise 10000 in 1997 and also in the Sun Fire family—the
midrange 4800, 4900, 6800, and 6900, and the large-scale F12K, F15K, E20K,
and E25K systems. Dynamic Domains are also available in the follow-on M4000,
M5000, M8000, and M9000 systems. Their implementation in the most recent
generation is described in Chapter 2, “Hard Partitioning: Dynamic Domains.”
On the CS6400, E10000, and the following generation (4800-25K) of systems,
this implementation provides complete electrical isolation between Dynamic
Domains. There is no single point of failure in a domain that would affect all of
the domains. However, a hardware failure of a component in the shared backplane
can affect multiple domains. Starting in 1993, Dynamic Domains could be recon-
figured without rebooting them.
Hewlett-Packard's (HP's) nPars feature was first made available on some mem-
bers of the PA-RISC-based HP 9000 series. It is also a feature of some of HP's
Integrity systems. In 2007, HP added the ability to reconfigure these partitions
without rebooting them.
Amdahl's Multiple Domain Facility (MDF) and subsequently IBM's mainframe
Logical Partitions (LPARs) are among the earliest implementations of hardware-
based partitioning, available since the 1980s. MDF and LPARs use specialized
hardware and firmware to create separate execution contexts with assigned
CPUs, RAM, and I/O channels. A domain or partition may have dedicated physical
CPUs or logical CPUs that are implemented on a physical CPU shared with other
domains and shared according to a priority weighting factor. Physical RAM is
assigned to one partition at a time, and can be added or removed from a partition
without rebooting it.