Red Hat Enterprise Linux 4: Installation Guide for x86, Itanium™, AMD64, and Intel® Extended Memory 64 Technology (Intel® EM64T)
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# Appendix C. Troubleshooting Your Installation of Red Hat Enterprise Linux

This appendix discusses some common installation problems and their solutions.

# C.1. You are Unable to Boot Red Hat Enterprise Linux

## C.1.1. Are You Unable to Boot With Your RAID Card?

If you have performed an installation and cannot boot your system properly, you may need to reinstall and create your partitions differently.

Some BIOSes do not support booting from RAID cards. At the end of an installation, a text-based screen showing the boot loader prompt (for example, `GRUB:`) and a flashing cursor may be all that appears. If this is the case, you must repartition your system.

Whether you choose automatic or manual partitioning, you must install your `/boot` partition outside of the RAID array, such as on a separate hard drive. An internal hard drive is necessary to use for partition creation with problematic RAID cards.

You must also install your preferred boot loader (GRUB or LILO) on the MBR of a drive that is outside of the RAID array. This should be the same drive that hosts the `/boot/` partition.

Once these changes have been made, you should be able to finish your installation and boot the system properly.

## C.1.2. Is Your System Displaying Signal 11 Errors?

A signal 11 error, commonly know as a segmentation fault, means that the program accessed a memory location that was not assigned.

If you receive a fatal signal 11 error during your installation, it is probably due to a hardware error in memory on your system's bus. A hardware error in memory can be caused by problems in executables or with the system's hardware. Like other operating systems, Red Hat Enterprise Linux places its own demands on your system's hardware. Some of this hardware may not be able to meet those demands, even if they work properly under another OS.

Ensure that you have the latest installation updates and images from Red Hat. Review the online errata to see if newer versions are available. If the latest images still fail, it may be due to a problem with your hardware. Commonly, these errors are in your memory or CPU-cache. A possible solution for this error is turning off the CPU-cache in the BIOS. You could also try to swap your memory around in the motherboard slots to check if the problem is either slot or memory related.

You can also try running the installation with only 256 MB of memory. This can be done by booting the installation program with the `mem=256M` boot option. To try this option, at the installation boot prompt, type:

    mem=xxxM

where xxx should be replaced with the amount of memory in megabytes.

This command allows you to override the amount of memory the kernel detects for the machine. This may be needed for some older systems where only 16MB is detected by the installation program (but more RAM is present in the system), and for some new machines where the video card shares the video memory with the main memory.

Another option is to perform a media check on your installation CD-ROMs. The Red Hat Enterprise Linux installation program has the ability to test the integrity of the installation media. It works with the CD, DVD, hard drive ISO, and NFS ISO installation methods. Red Hat recommends that you test all installation media before starting the installation process, and before reporting any installation-related bugs (many of the bugs reported are actually due to improperly-burned CDs). To use this test, type the following command at the `boot:` prompt (prepend with `elilo` for Itanium systems):

    linux mediacheck

For more information concerning signal 11 errors, refer to:

    http://www.bitwizard.nl/sig11/

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