How to Increase size of tmpfs file system ( OEL 6.3) for Oracle SGA mapping ?
tmpfs filesystem keeps the entire filesystem (with all it’s files) in virtual memory. All data is stored in memory, which means the data is temporary and will be lost after a reboot. If you unmount the filesystem, all data in there is gone. Typically it is mounted to /dev/shm .
- The default size of the filesystem is half of the installed memory in the system.
Temporary increase tmpfs filesystem
To increase the size, do the following: Modify /etc/fstab line to look something like this: tmpfs /dev/shm tmpfs defaults,size=16g 0 0 Remount tmpfs and verify : # mount -o remount tmpfs Verify : # df -h Filesystem Size Used Avail Use% Mounted on tmpfs 16G 232M 16G 2% /dev/shm
Make temporay changes permanent even after a reboot
- After a reboot the tmpfs filesystem is back to half of the system’s memory !
Strange, isn’t it ?
According to https://bugzilla.redhat.com/show_bug.cgi?id=669700 the following WA can be used to get this changed permanently.
Change /etc/rc.d/rc.sysinit from mount -f /dev/shm >/dev/null 2>&1 to mount /dev/shm >/dev/null 2>&1 or add to /etc/rc.local # remount tmpfs to read the size parameter mount -o remount tmpfs