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Version 3.1-en Solaris 10 Container Guide - 3.1 2. Functionality Effective: 30/11/2009
2.2.2. Logical partitions
[ug] A minimal operating system called the hypervisor, that virtualizes the interface between the
hardware and the OS of a computer, runs on the computer's hardware. A separate operating system
(guest operating system) can be installed on the arising so-called virtual machines.
In some implementations, the hypervisor runs as a normal application program; this involves
increased overhead.
Virtual devices are usually created from real devices by emulation; real and virtual devices are
assigned to the logical partitions by configuration.
Advantages:
• Application: All applications of the guest operating system are executable.
• Scalability: The capacity of a logical partition can be modified in some cases while running,
when the OS and the hypervisor support this.
• Separation: Applications are separated from each other; direct mutual influence via the OS is
not possible.
• OS versions: The partitions are able to run different operating systems/versions.
Disadvantages:
• HW maintenance: If a shared component fails, many or all logical partitions may be affected. An
attempt is made, however, to recognize symptoms of future failure by preventive analysis, in
order to segregate errors in advance.
• Separation: The applications can influence each other via shared hardware. One example for
this is the virtual network since the hypervisor has to emulate a switch. Virtual disks which are
located together on a real disk are “pulling away” the disk head from each other are another
example of this behavior. To prevent this from happening, real network interfaces or dedicated
disks can be used which, however, increases the cost for using logical partitions.
• OS maintenance: Each partition has to be administered separately. OS installation, patches and
the implementation of in-house standards must be done separately for each partition.
• Delegation: If the department responsible for the application/service requires root privileges, or
must communicate with computer operations regarding modifications. All aspects of the
operating system can be administered in the logical partition. This can affect security and can
become costly/time-consuming.
• Overhead: Each logical partition has its own operating system overhead; in particular the main
memory requirements of the individual systems are maintained.
Logical partitioning systems include the IBM VM operating system, IBM LPARs on z/OS and AIX, HP
vPars, as well as VMware and XEN. Sun offers Logical Domains (SPARC: since Solaris 10 11/06) as
well as Sun xVM VirtualBox (x86 and x64 architectures).
The Sun xVM server is in collaboration with the XEN community for x64 architectures in development.
The virtualization component (xVM Hypervisor) can already be used since OpenSolaris 2009.06.
11
Figure 3: [dd] Logical partitions
Server
OS
App
App 3App 2App 1