Archive for the tag 'linux'

Red Hat Enterprise Linux 6 FCoE Support.

FCoE Support in the Kickstart File

When using a kickstart file to install Red Hat Enterprise Linux 6.4, with the new fcoe kickstart option you can specify which Fibre Channel over Ethernet (FCoE) devices should be activated automatically in addition to those discovered by Enhanced Disk Drive (EDD) services.

Red Hat Enterprise Linux 6 Installation Guide has more Kickstart Options.

How to generate a crash dump on Redhat Linux

The Red Hat Crash Utility is a kernel-specific debugger. It is usually used for performing postmortem system analysis when the system panicked, locked up, or appears unresponsive.

Starting with the Red Hat Enterprise Linux 3 release, the crash utility is automatically installed during the system installation if the Development Tools package set is selected.

Test that Diskdump works. The following commands will crash your machine:

# echo 1 > /proc/sys/kernel/sysrq
# echo c > /proc/sysrq-trigger

Make sure that you run the above two commands in console (press Ctrl + Alt + F1), so that we can see what is happening when your system crashes. You have to perform this so that you can have a vmcore file to follow the rest of the paper. It will be located at /var/crash.

Red Hat Enterprise Linux 64-Bit Support

Red Hat Enterprise Linux 6 supports 64-bit processors; these processors can theoretically use up to 18 exabytes of memory. As of general availability (GA), Red Hat Enterprise Linux 6 is tested and certified to support up to 8TB of physical memory.

The size of memory supported by Red Hat Enterprise Linux 6 is expected to grow over several minor updates, as Red Hat continues to introduce and improve more features that enable the use of larger memory blocks. Examples of such improvements (as of Red Hat Enterprise Linux 6 GA) are:

Huge pages and transparent huge pages

Non-Uniform Memory Access improvements


Linux Network Time Protocol Setup

Linux Network Time Protocol Setup

We can also synchronize the system clock with a remote server over the Network Time Protocol ( NTP).

For the one-time synchronization only, use the ntpdate command:

Check whether the selected NTP server is accessible:

[root@fedora ~]# ntpdate -q
server, stratum 2, offset 0.014709, delay 0.25420
server, stratum 2, offset -0.007991, delay 0.21991
3 Oct 09:40:35 ntpdate[4083]: adjust time server offset -0.007991 sec
[root@fedora ~]#

Run the ntpdate command followed by one or more server addresses:

[root@fedora ~]# ntpdate
3 Oct 09:41:36 ntpdate[4092]: adjust time server offset 0.000724 sec

Enable the service.

[root@fedora ~]# systemctl status ntpd.service
ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled)
Active: inactive (dead) since Wed, 03 Oct 2012 09:42:42 +0530; 36s ago
CGroup: name=systemd:/system/ntpd.service

Oct 03 09:42:42 ntpd[4105]: ntpd 4.2.6p5@1.2349-o Fri Apr 27 08:37:16 UTC 2012 (1)

virtualization with Red Hat Enterprise Linux - System requirements.

This chapter lists system requirements for successfully running virtualization with Red Hat Enterprise Linux. Virtualization is available for Red Hat Enterprise Linux 5 Server.

The requirements for virtualization vary depending on the type of hypervisor. The Kernel-based Virtual Machine (KVM) and Xen hypervisors are provided with Red Hat Enterprise Linux 5. Both the KVM and Xen hypervisors support Full virtualization. The Xen hypervisor also supports Para-virtualization.

Minimum system requirements

6GB free disk space
2GB of RAM.

Recommended system requirements

6GB plus the required disk space recommended by the guest operating system per guest. For most operating systems more than 6GB of disk space is recommended.
One processor core or hyper-thread for each virtualized CPU and one for the hypervisor.
2GB of RAM plus additional RAM for virtualized guests.

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