How does tmpfs value in df -h relate to ipcs -a?
Hello Linux experts,
I seem to be having issues understanding Linux shared memory. I have setup shared memory usage for my Oracle database 11g. We use hugepages and therefore don't use AMM. Typing in ipcs -a shows that shared memory is being used as directed. When I type in df -h though the /dev/shm (tmpfs) usage shows 0. Can anyone explain why this is so?
My concern was that I allocated 40G to shared memory in the kernel params but the /dev/shm partition is only 24GB (1/2 ram). IPCS is showing the full 40GB being used.
I'm confused.
Much thanks in advance!
Ilya