ORA-27102: handling of outofmemory errors

ORA-27102: handling of outofmemory errors

Problem description:

Originally, SGA 4G and PGA 2G.

Alter system set sga_max_size = 30G scope = spfile;

Alter system set sga_target = 30G scope = spfile;

After,

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
Start again

SQL> startup
ORA-27102: out of memory
Linux-ia64 Error: 28: No space left on device

Solution:

(1)Getconf PAGE_SIZE in linux
16384 = 8 K

Indicates that the size of a page in the virtual memory is 8 KB.

(2)View cat/proc/sys/kernel/shmall

524288

Indicates that a maximum of 524288 pages are allowed to be shared.

(3) Calculate the page that can be shared:

524288*(16384/1024)/1024/1024 = 8G

No error is reported because SGA + PGA = 6G <8G. After sga = 30g is modified, ORA-27102: out of memory is reported only when the instance is started
Linux-ia64 Error: 28: No space left on device

(4)Change the shared memory to 128 GB.

128x1024*1024/8 K = 8388608

In linux: echo "8388608">/proc/sys/kernel/shmall

(5)Startup again. The instance can be started.