HugePage Implementation

- Single database instance 

- Mem: 528265812k (528 GB) 

Recommended values for SGA, PGA, SHARED_POOL, DB_CACHE and hugepages

SGA_TARGET=150G

SGA_MAX_SIZE=150G

PGA_AGGREGATE_TARGET=100G

SHARED_POOL_SIZE=50G

DB_CACHE_SIZE=70G

vm.nr_hugepages=77000

STEPS

• Log into DB as SYS user.
• create pfile from spfile;
• Take the backup of pfile;
• Change parameters 

              ALTER SYSTEM SET USE_LARGE_PAGES=ONLY SCOPE=SPFILE; 
                  ALTER SYSTEM SET SGA_TARGET=150G SCOPE=SPFILE; 
                  ALTER SYSTEM SET SGA_MAX_SIZE=150G SCOPE=SPFILE; 
                  ALTER SYSTEM SET PGA_AGGREGATE_TARGET=100G SCOPE=SPFILE; 
                  ALTER SYSTEM SET SHARED_POOL_SIZE=50G SCOPE=SPFILE; 
                  ALTER SYSTEM SET DB_CACHE_SIZE=70G SCOPE=SPFILE; 
                  ALTER SYSTEM SET MEMORY_MAX_TARGET=0 SCOPE=SPFILE; 
                  ALTER SYSTEM SET MEMORY_TARGET=0 SCOPE=SPFILE; 
                  ALTER SYSTEM SET SORT_AREA_SIZE=0 SCOPE=SPFILE;

• create pfile from spfile
• shut immediate;
• As root add below valules in sysctl.conf

              vm.nr_hugepages=77000

                  vm.hugetlb_shm_group=501 (To know the group use fgrep dba /etc/group)  

• As a root sysctl -w vm.max_map_count=262144
• As a root sysctl -p
• reboot server
• Edit pfile and Remove memory_max_target, memory_target and sort_area_size from pfile
• start database with pfile

                startup pfile=/u01/app/oracle/product/11.3.0/db_1/dbs/initXXX.ora

• create spfile from pfile
• shut immediate
• startup

Large Pages used by this instance (#pages) = HugePages_Total – HugePages_Free + HugePages_Rsvd

Ref.

• Huge Page Implementation Note 361468.1
• Large Pages Information in the Alert Log Note: 1392543.1
• Oracle Not Utilizing Hugepages (Doc ID 803238.1)
• Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration (Doc ID 401749.1)
• USE_LARGE_PAGES To Enable HugePages (Doc ID 1392497.1)
• Maximum SHMMAX values for Linux x86 and x86-64 (Doc ID 567506.1)
• Upon startup of Linux database get ORA-27102: out of memory Linux-X86_64 Error: 28: No space left on device (Doc ID 301830.1)