Redhat Enterprise 5.6 memory upgrade not recognized.
I recently upgraded the RAM in a Dell T610 Server from 32GB to 96GB and when I run a freemem or /cat/meminfo is still shows the original RAM amount. I already:
1. installed all Redhat system and kernel updates.
2. Updated the Grub.conf file to reflect the new memory size.
3. Applied all firmware and bios updates.
4. The BIOS does recognize and passes the memory test.
5. The memory type is Dell original RAM and compatible.
6. Redhat 5.6 supposed to recognize upto 1TB.
What's Next!
Nick
Responses
Community Member
70 points
Did you also try to edit the Grub settings directly from the boot screen by typing e on the selected kernel and add mem=xxm? Link below talked about that.
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Installation_Guide/s2-trouble-ram.html
Guru
6863 points
Hey Nick, can you please provide us with
uname -a
cat /etc/redhat-release
cat /proc/cmdline
dmidecode -s bios-version
dmidecode | grep "Memory Device" | wc -l
-- see if that last line matches the number of DIMMS you just installed. Or, better yet...
dmidecode | grep -A5 "Memory Device" | grep Size
Then, do the following and see if any of the modules are detected, but not online:
grep line /sys/devices/system/memory/*/state
Guru
6863 points
Nick - I have to admit, I'm a bit stumped. To be fair, I have never used a "xen" kernel (I'm a KVM/RHEV guy myself). The XEN kernel may alter the OS in a way that my troubleshooting might not be the best method. I apologize we haven't come to a solution/conclusion yet.
I just checked my R610 with the same memory 12x8GB (which your OS sees from the dmidecode output). However, my bios is still a 2.x release.
The fact that /sys/devices/system/memory/memory*/state is missing is bizarre to me.
Do you have 2 processors installed in that system? I would be surprised that dmidecode could "see" the memory, but not access it - if it was due to only a single processor configuration. Even still - I would expect top or free to show 48GB, not 32GB.
Another thing to consider - I know you mentioned you tried a few different values - have you tried using mem=98304M - which is 8192x12 (I'm grasping at straws here) or remove it altogether. I did not need to specify my memory by hand. If you are able, I would try to boot to the non-xen kernel (just to see if it recognizes the memory).
[root@rhnsat01 ~]# uname -n; cat /etc/redhat-release; dmidecode -s bios-version; dmidecode | grep "Memory Device" | wc -l; dmidecode | grep -A5 "Memory Device" | grep Size
uname -n: Linux rhnsat01.company.com 2.6.18-348.12.1.el5 #1 SMP Mon Jul 1 17:54:12 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux
redhat-release: Red Hat Enterprise Linux Server release 5.9 (Tikanga)
bios-version: 2.0.13
mem number: 12
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
Size: 8192 MB
I think this is important - note how many "memory devices" I have
[root@rhnsat01 ~]# grep online /sys/devices/system/memory/memory*/state | wc -l
774
Guru
6863 points
Hey Nick - I hate to hijack a thread as I know you are certainly looking for an answer. Do you actually need Xen? Red Hat selected KVM and it's fully supported by them. I believe converting your XEN Virtual Machines to KVM should be fairly straight-forward. I do not know your requirements, but I thought I would offer that as a possible solution. As I admitted previously, I do not know XEN, but I suspected that was the issue.
Your system likely has the non-XEN kernels installed and you can try to boot to them by selecting the other kernel at boot.
You can see if the non-XEN kernels are a.) installed and b.) addressed in your grub
rpm -qa kernel
grep kern /boot/grub/grub.conf |awk '{ print $2 }'
Red Hat
Active Contributor
307 points
Hello,
According to Red Hat's knowledgebase article, https://access.redhat.com/site/articles/3976, On RHEL5, the maximum support memory is 512G. The minimum requirement of memory is 512MB. This particular article doesn't mention the xen kernel though. However, you should be able to install the non-xen kernel and then check to see if the extra memory does show up.
Guru
6222 points
sosreport can be uploaded to dropbox.redhat.com in the directory /incoming
add the file-name to the Red Hat case.
Does the DELL post show the new amount of memory?
Does the server have enough CPU's to support this new number of DIMMs?
For if you use AMD processors you have distributed memory management.
Kind regards,
Jan Gerrit Kootstra
Guru
6863 points
In almost any case, KVM is the preferable option. To answer your question: 1TB for RHEL 5.
http://www.redhat.com/resourcelibrary/articles/virtualization-limits-rhel-hypervisors
The different hypervisor vendors seem to go back-and-forth regarding which is the best, but you will often find that KVM (and RHEV) supports more memory, more CPUs, more vCPUs, has better benchmarks, etc...
So - a better question: If your physical node is simply a Hypervisor, could you run RHEL 6 instead?
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