Reconfigure OS Parameters After Linux Server Memory Upgrade


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

1) Change ëmemlockí 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
2) Change ënr_hugepagesí in /etc/sysctl.conf. 43GB memory( 60% of whole memory ) is allocated to hugepages.

vm.nr_hugepages = 22016
3) 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
4) Reconfigure SGA_TARGET and SGA_MAX_SIZE of database instances. Make sure the total SGA usage is less than vm.nr_hugepages = 22016( 43GB).