3 Replies Latest reply on May 4, 2012 9:19 AM by Brent Harlow

    OEL5 not recognising newly installed RAM

    Brent Harlow
      Hi all,

      I've just replaced all the existing 4x1GB RAM modules with 4x2GB ones on OEL5 but the system is not showing anymore than the original 4GB.

      *[oracle@test2 ~]$ uname -a*
      Linux test2.hmdclinical.com 2.6.18-194.el5 #1 SMP Mon Mar 29 20:06:41 EDT 2010 i686 i686 i386 GNU/Linux

      *[oracle@test2 ~]$ sudo dmidecode -t 16*
      # dmidecode 2.10
      SMBIOS 2.3 present.

      Handle 0x1000, DMI type 16, 15 bytes
      Physical Memory Array
      Location: System Board Or Motherboard
      Use: System Memory
      Error Correction Type: Multi-bit ECC
      Maximum Capacity: 8 GB
      Error Information Handle: Not Provided
      Number Of Devices: 4

      *[oracle@test2 ~]$ sudo dmidecode -t 17 | grep Size*
      Size: 2048 MB
      Size: 2048 MB
      Size: 2048 MB
      Size: 2048 MB


      *[oracle@test2 ~]$ cat /proc/meminfo*
      MemTotal: 3893868 kB
      MemFree: 3181000 kB
      Buffers: 28404 kB
      Cached: 335580 kB
      SwapCached: 0 kB
      Active: 391172 kB
      Inactive: 291220 kB
      HighTotal: 3014492 kB
      HighFree: 2351764 kB
      LowTotal: 879376 kB
      LowFree: 829236 kB
      SwapTotal: 5931000 kB
      SwapFree: 5931000 kB
      Dirty: 104 kB
      Writeback: 0 kB
      AnonPages: 318384 kB
      Mapped: 19184 kB
      Slab: 18592 kB
      PageTables: 1916 kB
      NFS_Unstable: 0 kB
      Bounce: 0 kB
      CommitLimit: 7877932 kB
      Committed_AS: 460624 kB
      VmallocTotal: 114680 kB
      VmallocUsed: 5564 kB
      VmallocChunk: 108900 kB
      HugePages_Total: 0
      HugePages_Free: 0
      HugePages_Rsvd: 0
      Hugepagesize: 4096 kB

      I read on the red hat installation troubleshooting about adding a line to the grub.conf file so tried that but made no difference


      *[oracle@test2 ~]$ sudo cat /boot/grub/grub.conf*
      # 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/sda
      default=0
      timeout=5
      splashimage=(hd0,0)/grub/splash.xpm.gz
      hiddenmenu
      title Enterprise Linux (2.6.18-194.el5)
      root (hd0,0)
      kernel /vmlinuz-2.6.18-194.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
      initrd /initrd-2.6.18-194.el5.img
      append="mem=8192M"

      Help please !

      Cheers,
      Brent
        • 1. Re: OEL5 not recognising newly installed RAM
          Dude!
          The problem could be your CPU or installed kernel.

          The original first i686 CPU's can only address up to 4GB of memory.
          The 32-bit no-PAE kernel can only address up to 4 GB of memory.

          Intel introduced the PAE extensions for later i686 CPU's allowing 36-bit addressing and memory up to 64 GB.
          The 32-bit PAE kernel can address up to 16 GB reliably.

          1. Check if your CPU supports PAE:

          <pre>
          grep --color=always -i PAE /proc/cpuinfo
          </pre>

          2. Update the kernel

          Setup Oracle Public Yum repository http://public-yum.oracle.com/
          <pre>
          yum install kernel-PAE
          </pre>
          • 2. Re: OEL5 not recognising newly installed RAM
            Brent Harlow
            Hi Dude,

            Thanks for that ! I've run the command, the output is ...

            *[oracle@test2 ~]$ grep --color=always -i PAE /proc/cpuinfo*
            flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr
            flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr
            flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr
            flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr

            I assume that this means that the CPU odes support PAE ?
            • 3. Re: OEL5 not recognising newly installed RAM
              Brent Harlow
              Hi Dude,

              Using yum I installed the PAE kernel. To my disappointment on reboot nothing had changed but then on checking the grub.conf file I saw that there was now 2 entries, one for the old kernel and one for the new PAE one. I changed the default parameter from 1 back to 0 to use the first (PAE) kernel in the list, rebooted and like magic, I now have access to all of my 8Gb.

              Thanks very much !!