>From /proc/meminfo & top & dmesg, our 64-bit hardware
showed only a total of 3GB RAM.
Physically 16GB RAM were inserted.
Q1:
Is top/dmesg/meminfo giving the right info or how to get
RHEL 5.1 to fully utilize the 16GB
Q2:
Is 32 or 64 bit RHEL 5.x better at utilizing memory?
The box hosts 7 Oracle instances
Is there a lot of effort involved to upgrade from 32 bit
to 64 bit RHEL 5.1?
Tks
U
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> >From /proc/meminfo & top & dmesg, our 64-bit hardware
> showed only a total of 3GB RAM.
>
> Physically 16GB RAM were inserted.
>
> Q1:
> Is top/dmesg/meminfo giving the right info or how to get
> RHEL 5.1 to fully utilize the 16GB
Use a PAE kernel or the 64 bit version of RHEL.
> Q2:
> Is 32 or 64 bit RHEL 5.x better at utilizing memory?
> The box hosts 7 Oracle instances
64 bit OS will support 64 bit processes (i.e. your oracle instances), which can address more than 4GB of memory each. PAE will only support 32 bit processes, which can only see 4GB of memory, but the system itself will recognize all 16GB.
> Is there a lot of effort involved to upgrade from 32 bit
> to 64 bit RHEL 5.1?
I'm not sure that's a supported upgrade path. Your best bet will be a fresh install of 64 bit RHEL and migrate to it.
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> 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
I don't know exactly how Linux counts memory but on other platforms you will often see this because RAM of other adapters (video being the main culprit) counts as part of the 4GB so only 3 to 3.5GB of system RAM ends up being addressable. So that would be my guess in this circumstance.
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>> 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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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@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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On Wed, Dec 23, 2009 at 8:35 AM, Ramakrishnan Seshadhri <
ramakrishnan42@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@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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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@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 donīt know why other servers show
> you the memory correctly
>
> Greetings
>
> ESG
>
> 2009/12/23 sunhux G <sunhux@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@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@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"
> > > >
> > > > --
> > > > redhat-list mailing list
> > > > unsubscribe mailto:redhat-list-request@redhat.com
> ?subject=unsubscribe
> > > > https://www.redhat.com/mailman/listinfo/redhat-list
> > > >
> > > --
> > > redhat-list mailing list
> > > unsubscribe mailto:redhat-list-request@redhat.com?subject=unsubscribe
> > > https://www.redhat.com/mailman/listinfo/redhat-list
> > >
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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@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@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 donīt know why other servers show
> > you the memory correctly
> >
> > Greetings
> >
> > ESG
> >
> > 2009/12/23 sunhux G <sunhux@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@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@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"
> > > > >
> > > > > --
> > > > > redhat-list mailing list
> > > > > unsubscribe mailto:redhat-list-request@redhat.com
> > ?subject=unsubscribe
> > > > > https://www.redhat.com/mailman/listinfo/redhat-list
> > > > >
> > > > --
> > > > redhat-list mailing list
> > > > unsubscribe mailto:redhat-list-request@redhat.com
> ?subject=unsubscribe
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> > > >
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RHEL 5.1 (32 bit) shows 3GB RAM though there's 16GB physical
