RHEL 5.1 (32 bit) shows 3GB RAM though there's 16GB physical

Ramakrishnan Seshadhri ramakrishnan42 at gmail.com
Thu Dec 24 05:05:02 UTC 2009 

Hi,

Yes ! there is no harm in commenting out the kernel without PAE.
The change in the kernel will absolutely not have any impact on your oracle
environment.
I had done this many times on my oracle environment and nothing has gone
wrong.
Is your physical memory correctly showing up now?

Cheers,
Ram


On 12/24/09, sunhux G <sunhux at gmail.com> wrote:
>
> Hi Chaps,
>
>
> rpm -qa | grep -i pae       gave
> kernel-PAE-2.6.18-53.el5
>
> &    ls -d  /boot/vm*      gave
> vmlinuz-2.6.18-53.el5
> vmlinuz-2.6.18-53.el5PAE
>
> & /etc/grub.conf has both the above.
>
>
> So can I say the best thing to do now is :
> comment out in grub.conf the non-Pae entry so that by default
> it boots up from the PAE kernel & nobody would accidentally
> boots up from the non-PAE
>
> Also, is there any impact to Oracle & web applications
> if I boot up from the PAE kernel?  Any precautions?
>
>
> Thanks
>
> On Wed, Dec 23, 2009 at 7:39 PM, Ramakrishnan Seshadhri <
> ramakrishnan42 at gmail.com> wrote:
>
> > Hi Sunhux,
> >
> > As I told you earlier you need to install PAE kernel so that Linux shows
> > the
> > correct memory.
> >
> > Install these packages
> >
> > kernel-PAE-2.6.18-128.1.14.el5
> > kernel-PAE-2.6.18-164.el5
> > kernel-PAE-2.6.18-128.1.1.el5
> >
> > They are present in the Linux DVD under "<DVD DRIVE>\server" directory.
> >
> > Once you install this follow the below steps
> >
> > 1. Install the RPM
> > 2. Reboot the system
> > 3. during the boot loaded screen press arrow keys
> > 4. Here you will find 2 options, one with the normal Kernel and one with
> > PAE
> > 5. Choose the PAE kernel version and press enter.
> > 6. Now your system should load the PAE kernel and the memory shows up.
> > 7. Use "free" command to check the physical memory.
> >
> > Hope this helps. Once your memory is showing correctly go to grub.conf to
> > set the PAE kernel as the default option to boot your system. If you dont
> > do
> > that everytime you reboot it will take the normal kernel and your phy.
> > memory will not show up again.
> >
> > Regards,
> > Ram
> >
> >
> > On 12/23/09, ESGLinux <esggrupos at gmail.com> wrote:
> > >
> > > Hi,
> > >
> > > just one thing, in my servers with 32 bits I need to install de kernel
> > PAE
> > > as they have said you:
> > >
> > > uname -a
> > > Linux server 2.6.18-164.el5PAE #1 SMP Tue Aug 18 15:59:11 EDT 2009 i686
> > > i686
> > > i386 GNU/Linux
> > >
> > > rpm -qa | grep -i pae
> > > kernel-PAE-2.6.18-128.1.14.el5
> > > kernel-PAE-2.6.18-164.el5
> > > kernel-PAE-2.6.18-128.1.1.el5
> > >
> > > I think you need this kind of kernel, I don´t know why other servers
> show
> > > you the memory correctly
> > >
> > > Greetings
> > >
> > > ESG
> > >
> > > 2009/12/23 sunhux G <sunhux at gmail.com>
> > >
> > > > For other RHEL servers that shows the RAM amt correctly,
> > > > "uname -a" & "dmesg" show the following :
> > > >
> > > > # uname -a
> > > > Linux SvrWith_8GBRam 2.6.9-67.0.7.ELsmp #1 SMP Wed Feb 27 04:48:20
> EST
> > > 2008
> > > > i686 i686 i386 GNU/Linux
> > > >
> > > > # dmesg | grep -i mem
> > > > 8320MB HIGHMEM available.
> > > >
> > > >
> > > > For the "weird" server, the uname, dmesg & top are as follows :
> > > > (I'll collect "dmidecode | grep -e Memory\ Device$ -A5" tomorrow)
> > > >
> > > > # uname -a
> > > > Linux SvrWith_3GbRam 2.6.18-53.el5 #1 SMP Wed Oct 10 16:34:02 EDT
> 2007
> > > i686
> > > > i686 i386 GNU/Linux
> > > >
> > > > # dmesg | grep -i mem
> > > > 3200MB HIGHMEM available.
> > > > 896MB LOWMEM available.
> > > > Memory for crash kernel (0x0 to 0x0) notwithin permissible range
> > > >  HighMem zone: 819200 pages, LIFO batch:31
> > > > Memory: 3365612k/4194304k available (2080k kernel code, 40228k
> > reserved,
> > > > 869k data, 220k init, 2489644k highmem)
> > > > Freeing initrd memory: 2468k freed
> > > >  MEM window: f2000000-f5ffffff
> > > >  MEM window: f6000000-f60fffff
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > >  MEM window: disabled.  <== anything wrong with this?
> > > > highmem bounce pool size: 64 pages
> > > >
> > > >
> > > > top - 00:18:20 up 3 days, 12:32,  2 users,  load average: 0.14, 0.07,
> > > 0.02
> > > > Tasks: 155 total,   1 running, 154 sleeping,   0 stopped,   0 zombie
> > > > Cpu(s):  0.0%us,  0.2%sy,  0.0%ni,
> 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,
> > > >  0.0%st
> > > > Mem:   3369208k total,  3284572k used,    84636k free,   185648k
> > buffers
> > > > Swap:  8193108k total,      200k used,  8192908k free,  2756496k
> cached
> > > >
> > > >
> > > > # more /proc/meminfo
> > > > MemTotal:      3369208 kB
> > > > MemFree:         84760 kB
> > > > Buffers:        185668 kB
> > > > Cached:        2756484 kB
> > > > SwapCached:          0 kB
> > > > Active:         508672 kB
> > > > Inactive:      2635140 kB
> > > > HighTotal:     2489644 kB
> > > > HighFree:        12244 kB
> > > > LowTotal:       879564 kB
> > > > LowFree:         72516 kB
> > > > SwapTotal:     8193108 kB
> > > > SwapFree:      8192908 kB
> > > >
> > > >
> > > > On Wed, Dec 23, 2009 at 8:35 AM, Ramakrishnan Seshadhri <
> > > > ramakrishnan42 at gmail.com> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > What is your Linux Kernel Version. Is it a PAE kernel (Physical
> > Address
> > > > > xtension)
> > > > >
> > > > > Provide the output of  # uname -a.
> > > > >
> > > > > If your kernel is not a PAE kernel it wont detect your physical
> > memory
> > > > more
> > > > > than 3072 MB.
> > > > >
> > > > > Hope it helps your situation.
> > > > >
> > > > > Ram
> > > > >
> > > > > On Tue, Dec 22, 2009 at 10:32 PM, Eugene Vilensky <
> > evilensky at gmail.com
> > > > > >wrote:
> > > > >
> > > > > > >> why is "top" or "dmesg" showing only 3GB RAM
> > > > > > >> instead of 4GB if 4GB is the max the 32 bit RHEL
> > > > > > >> can support?
> > > > > > >>
> > > > > > >> Supposedly there's 16GB physical RAM inserted
> > > > > > >> in the hardware
> > > > > >
> > > > > > Could you copy/paste your exact top output as well as the output
> of
> > > > > > "dmidecode | grep -e Memory\ Device$ -A5"
> > > > > >
> > > > > > --
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