Chapter 12. Introduction to Para-virtualized Drivers
provide increased performance for fully virtualized Red Hat Enterprise Linux guests. Use these drivers if you are using fully virtualized Red Hat Enterprise Linux guests and require better performance.
The RPM packages for the para-virtualized drivers include the modules for storage and networking para-virtualized drivers for the supported Red Hat Enterprise Linux guest operating systems. These drivers enable high performance throughput of I/O operations in unmodified Red Hat Enterprise Linux guest operating systems on top of a Red Hat Enterprise Linux 5.1 (or greater) host.
The supported guest operating systems are:
Red Hat Enterprise Linux 3
Red Hat Enterprise Linux 4
Red Hat Enterprise Linux 5
Architecture support for para-virtualized drivers
The minimum guest operating system requirements are architecture dependent. Only x86 and x86-64 guests are supported.
The drivers are not supported on Red Hat Enterprise Linux guest operating systems prior to Red Hat Enterprise Linux 3 .
Using Red Hat Enterprise Linux 5 as the virtualization platform allows System Administrators to consolidate Linux and Windows workloads onto newer, more powerful hardware with increased power and cooling efficiency. Red Hat Enterprise Linux 4 (as of update 6) and Red Hat Enterprise Linux 5 guest operating systems are aware of the underlying virtualization technology and can interact with it efficiently using specific interfaces and capabilities. This approach can achieve similar throughput and performance characteristics compared to running on the bare metal system.
As this approach requires modifications in the guest operating system not all operating systems and use models can use para-virtualized virtualization. For operating systems which can not be modified the underlying virtualization infrastructure has to emulate the server hardware (CPU, Memory as well as IO devices for storage and network). Emulation for IO devices can be very slow and will be especially troubling for high-throughput disk and network subsystems. The majority of the performance loss occurs in this area.
The para-virtualized device drivers part of the distributed RPM packages bring many of the performance advantages of para-virtualized guest operating systems to unmodified operating systems because only the para-virtualized device driver (but not the rest of the operating system) is aware of the underlying virtualization platform.
After installing the para-virtualized device drivers, a disk device or network card will continue to appear as a normal, physical disk or network card to the operating system. However, now the device driver interacts directly with the virtualization platform (with no emulation) to efficiently deliver disk and network access, allowing the disk and network subsystems to operate at near native speeds even in a virtualized environment, without requiring changes to existing guest operating systems.
The para-virtualized drivers have certain host requirements. 64 bit hosts can run:
The para-virtualized drivers only work on 32 bit Red Hat Enterprise Linux hosts for 32 bit guests.
12.1. System requirements
This section provides the requirements for para-virtualized drivers with Red Hat Enterprise Linux.
Before you install the para-virtualized drivers the following requirements (listed below) must be met.
Red Hat Enterprise Linux 4.7 and 5.3 and newer
All version of Red Hat Enterprise Linux from 4.7 and 5.3 have the kernel module for the para-virtualized drivers, the
pv-on-hvm module, in the default kernel package. That means the para-virtualized drivers are available for Red Hat Enterprise Linux 4.7 and newer or 5.3 and newer guests.
You will need the following RPM packages for para-virtualized drivers for each guest operating system installation.
Red Hat Enterprise Linux 5 requires:
Red Hat Enterprise Linux 4 requires:
Red Hat Enterprise Linux 3 requires:
Minimum host operating system version
Minimum guest operating system version
Red Hat Enterprise Linux 5.1 and higher
Red Hat Enterprise Linux 4 Update 6 and higher
Red Hat Enterprise Linux 3 Update 9 and higher
You require at least 50MB of free disk space in the