ORA-27102: out of memory Linux-X86_64 Error

Shared Memory – startup database – ORA-27102: out of memory Linux-X86_64 Error: 28: No space left on device

SQLgt startupORA-27102 out of memoryLinux-x8664 Error 28 No space left on deviceI have used RHEL X8664 memory 32GB and setted sgamaxsize20G sgatarget20G and … cat procsyskern

SQL> startup 

ORA-27102: out of memory 

Linux-x86_64 Error: 28: No space left on device 

I have used RHEL X86_64 + memory (32GB) and setted sga_max_size=20G + sga_target=20G and … 

$ cat /proc/sys/kernel/shmmax 

26843545600 

What wrong with my kernel tuning… 

So, I checked metalink (301830.1) and some recommend from RHEL 

They told; set SHMALL to the total amount of physical RAM divided by page size. 

SHMALL => Total amount of shared memory available (bytes or pages) 

then: 

Check Page Size: 

$ getconf PAGE_SIZE 

4096 

Determine the system wide maximum number of shared memory pages: 

$ cat /proc/sys/kernel/shmall 

2097152 

=> My system 64bits with memory 32GB, 

then 1024*1024*1024*32/4096 = 8388608 

So, change kernel.shmall = 8388608 

$ su – root 

# echo 8388608 > /proc/sys/kernel/shmall 

Or 

modify /etc/sysctl.conf file: 

kernel.shmall=8388608 

and 

# sysctl -p 

After changed… check and startup database again: 

$ cat /proc/sys/kernel/shmall 8388608 

SQL> startup . . . 

— NO ERROR — 

From this idea with memory 32GB 

mem=$(free|grep Mem|awk ‘{print$2}’) 

totmem=$(echo “$mem*1024″|bc) 

huge=$(grep Hugepagesize /proc/meminfo|awk ‘{print $2}’) 

max=$(echo “$totmem*75/100″|bc) 

all=$(echo “$max/$huge”|bc) 

echo “kernel.shmmax = $max” 

echo “kernel.shmall = $all” 

Result: 

kernel.shmmax = 25213120512, 

kernel.shmall = 12311094 

However, This case “ORA-27102: out of memory Linux-X86_64 Error: 28: No space left on device” , 

solved by setting

SHMALL = MemTotal(byte)/PAGE_SIZE