Installation guide

Technology Previews

• non-exclusive access to storage devices

In addition, the following issues still exist in FireWire:

• a memory leak in the SBP2 driver may cause the machine to become unresponsive.

• a code in this version does not work properly in big-endian machines. This could lead to

unexpected behavior in PowerPC.

ktune

This release includes ktune (from the ktune package), a service that sets several kernel tuning

parameters to values suitable for specific system profiles. Currently, ktune only provides a profile

for large-memory systems running disk-intensive and network-intensive applications.

The settings provides by ktune do not override those set in /etc/sysctl.conf or through the

kernel command line. ktune may not be suitable on some systems and workloads; as such, you

should test it comprehensively before deploying to production.

You can disable any configuration set by ktune and revert to your normall settings by simply

stopping the ktune service using service ktune stop (as root).

SGPIO Support for dmraid

Serial General Purpose Input Output (SGPIO) is an industry standard communication method

used between a main board and a variety of internal and external hard disk drive bay enclosures.

This method can be used to control LED lights on an enclosure through the AHCI driver interface.

In this release, SGPIO support in dmraid is included as a technology preview. This will allow

dmraid to work properly with disk enclosures.

GCC 4.3

The Gnu Compiler Collection version 4.3 (GCC4.3) is now included in this release as a

Technology Preview. This collection of compilers include C, C++, and Fortran 95 compilers along

with support libraries.

Note that in the gcc43 packages, the default for the gnu89-inline option has been changed

to -fgnu89-inline, whereas upstream and future updates of Red Hat Enterprise Linux 5 will

default to -fno-gnu89-inline. This is necessary because many headers shipped as part of

Red Hat Enterprise Linux 5 expect GNU in-line semantics instead of ISO C99 semantics. These

headers have not been adjusted to request GNU in-line semantics through attributes.

Kernel Tracepoint Facility

In this update, a new kernel marker/tracepoint facility has been implemented as a Technology

Preview. This interface adds static probe points into the kernel, for use with tools such as

SystemTap.

Device Failure Monitoring of RAID sets

Device Failure Monitoring, using the tools dmraid and dmevent_tool, is included in Red Hat

Enterprise Linux 5.3 as a Technology Preview. This provides the ability to watch and report device

failures on component devices of RAID sets.