Tuesday, July 27, 2010

Enabling hugemem support in 32 bit RHEL

 

 

Here I have taken 32 bit RHEL 4.8 and upgraded the kernel to support “hugemem”:

1.

Pick the “hugemem” kernel:kernel-hugemem-2.6.9-89.EL.i686.rpm

2. It will put the entry for “hugemem” kernel in the file below then editing the file make “hugemem” kernel the default kernel for the AppServer.

cat /boot/grub /menu.lst

# grub.conf generated by anaconda

#

# Note that you do not have to rerun grub after making changes to this file

# NOTICE:  You have a /boot partition.  This means that

#          all kernel and initrd paths are relative to /boot/, eg.

#          root (hd0,0)

#          kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00

#          initrd /initrd-version.img

#boot=/dev/cciss/c0d0

default=1-- that  is it’s picking the second entry in the file which does not support hugemem

 

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Red Hat Enterprise Linux ES (2.6.9-89.ELsmp)

        root (hd0,0)

        kernel /vmlinuz-2.6.9-89.ELsmp ro root=/dev/VolGroup00/LogVol00 rhgb quiet

        initrd /initrd-2.6.9-89.ELsmp.img

title Red Hat Enterprise Linux ES-up (2.6.9-89.EL)

       root (hd0,0)

        kernel /vmlinuz-2.6.9-89.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet

        initrd /initrd-2.6.9-89.EL.img

======================== Install log =====================================================

[root@server kernel_rpms]# rpm -ivh kernel-hugemem-2.6.9-89.EL.i686.rpm > kernel-hugemem-log

warning: kernel-hugemem-2.6.9-89.EL.i686.rpm: V3 DSA signature: NOKEY, key ID db42a60e

[root@server1 kernel_rpms]# cat kernel-hugemem-log

Preparing...                ##################################################

kernel-hugemem              ##################################################

Now, after editing   “/boot/grub /menu.lst “

 

default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux ES (2.6.9-89.ELhugemem)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-89.ELhugemem ro root=/dev/VolGroup00/LogVol00 rhgb quiet
        initrd /initrd-2.6.9-89.ELhugemem.img
title Red Hat Enterprise Linux ES (2.6.9-89.ELsmp)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-89.ELsmp ro root=/dev/VolGroup00/LogVol00 rhgb quiet
        initrd /initrd-2.6.9-89.ELsmp.img
title Red Hat Enterprise Linux ES-up (2.6.9-89.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-89.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet
        initrd /initrd-2.6.9-89.EL.img

So,

[root@app1 grub]# uname -a
Linux siebelapp1 2.6.9-89.ELhugemem #1 SMP Mon Apr 20 10:45:44 EDT 2009 i686 i686 i386 GNU/Linux

 

If you don’t edit the menu.lst as per thr kernel sequence in that case though you have installed the kernel but it will not load and thus “uname –a” will not reflect the same.

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