How to Make ASM Instance to Use HugePages

The ASM instance is configured in the same way as normal databases instance for using hugepages in Linux 7. But ASM is not using hugepages, while the normal instance is using hugepages. There are enough free hugepages available  as per /etc/meminfo.

Let’s configure ASM to use HugePages.

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Reconfigure OS Parameters After Linux Server Memory Upgrade

Adjust OS memory parameters after more or less memory available

One of the Oracle database server ‘s memory is to be upgraded from 48GB to 72GB, so some parameters should be adjusted to take advantage of the newly added memory.

Change memlock Parameter

Modify “memlock” parameter in /etc/security/limits.conf to 70G, which is for hugepage purpose. This parameter can be bigger than SGA, up to or even bigger than memory size.

oracle  soft      memlock  73400320
oracle  hard      memlock  73400320
  grid  soft      memlock  73400320
  grid  hard      memlock  73400320

Change nr_hugepages Parameter

Change parameter ‘nr_hugepages’  in /etc/sysctl.conf.
43GB memory( 60% of whole memory ) is allocated to hugepages.

vm.nr_hugepages = 22016

Change shmmni, shmall and shmmax  values in /etc/sysctl.conf

 a)Keep kernel.shmmni = 4096

b) kernel.shmall=13369344 (51GB)  = 70% of whole memory divided by page size 4096.

c ) kernel.shmmax=38654705664( 36GB) =  50% of the whole memory size.

kernel.shmmni = 4096
kernel.shmall = 13369344
kernel.shmmax = 38654705664


Make sure the total SGA usage is less than vm.nr_hugepages = 22016( 43GB).