No, hardware must meet certain requirements to support full virtualization in Red Hat Enterprise Linux 5. For x86_64-based systems, the processor must support Intel VT-x or AMD-V technology. For Itanium2-based systems, the system must use a Montecito (or newer) processor.
In addition to CPU support, the system BIOS must also support full virtualization. Please contact the system vendor to determine if the BIOS supports full virtualization.
(Note that if this Knowledgebase article was linked from a system listing on the Red Hat Hardware Catalog, the system in question does not support full virtualization.) » Read more
Release Found: Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 4 Update 5
This is a new feature that has been requested in the Red Hat Enterprise Linux product line. The supported algorithms are DES, MD5, and SHA-256/512. They will be available after the upcoming updates releases as well as in Rawhide. The new algorithms will be configurable via Kickstart only. Here is the correct code. » Read more
At the moment, JBoss Technical Support is available in English. Support for other languages may be added at a future time.
When transferring an existing Red Hat Support case in another language to JBoss Support, please be prepared to provide a description of the case in English for the JBoss engineer.
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In the event that a process is not achieving the desired performance performance benchmarks, it can be helpful to set CPU affinity, real-time scheduling policy and real-time scheduling priority. Experimenting with different options using the taskset and chrt commands can help determine if this approach will provide the desired results.
The taskset sets CPU affinity for a process. The chrt sets real time scheduling options. The two commands can be used in tandem. For example:
taskset -c 2-3 chrt -f 1 <command>
The above usage would force <command> to run on CPUs 2 through 3, using the “fifo” scheduling policy at priority level 1. The results of using these options depend on the workload of the application, as well as the load of the system in general.
For more information on the taskset and chrt commands, see their respective man pages. For more information on setting these attributes within an application, rather than when launching the application, see man 2 sched_setaffinity and man 2 sched_setscheduler.
In Red Hat Enterprise Linux 5, device-mapper-multipath is installed by default. This is a change from Red Hat Enterprise Linux 4. If a third party multipathing solution is in use, device-mapper-multipath should be disabled to avoid any conflict between multiple multipathing technologies. To disable device-mapper-multipath, turn it off with the following command:
chkconfig multipathd off
In addition, make sure the /etc/sysconfig/mkinitrd/multipath file has the following line:
MULTIPATH=NO
By default, /etc/multipath.conf has all devices blacklisted. If this default configuration has been changed, the change should be reverted. If the devices are not blacklisted, then running the multipath command could cause a conflict with other multipathing software. The /etc/multipath.conf file should contain the following:
# Blacklist all devices by default. Remove this to enable multipathing
# on the default devices.
blacklist {
devnode "*"
}
These steps will ensure that device-mapper-multipath does not conflict with any other multipathing solution in use.
If the parmfile is loaded directly to memory like when using the LPAR load mechanism, the kernel cannot handle parmfile formats with multiple lines. It is recommended to place all boot parameters on one line. » Read more
I have noticed that my Red Hat Enterprise Linux 5 and/or Red Hat Enterprise Linux 5.1 system very occasionally hang at the end of the reboot / shutdown process. What can I do to avoid this?
This issue affects Red Hat Enterprise Linux 5 releases before Red Hat Enterprise Linux 5.2 and is due to a bug in cpufreq locking that may deadlock when the modules are unloaded, which is what happens at reboot and shutdown very late in the process.
To resolve this issue, update the systems kernel to at least the Red Hat Enterprise Linux 5.2 kernel. Alternatively, work around the problem by disabling cpuspeed with:
# chkconfig cpuspeed off # service cpuspeed stop
This does means the loss of some energy efficiency.