ORA-27125 on linux

For a 2.6.x kernel with HUGETLB enabled you can obtain an ORA-27125: unable to create shared memory segment.

A proposed solution is to insert in /etc/sysctl.conf

vm/disable_cap_mlock=1
vm/nr_hugepages=2048

Where nr_hugepages has to be set accordly with your available RAM.

However it only works on kernel patched to have disable_cap_mlock in proc (suse is an example) and it could represent a security issue.

Instead if you are using other distribution and a standard kernel from 2.6.7 (maybe you can find some backport) you could modify your sysctl.conf in this fashion:

vm/nr_hugepages=2048
vm/hugetlb_shm_group=55

Where hugetlb_shm_group contains the group of you oracle user (the one, other than root, that should access hugetlb.

I'm testing on kernel 2.6.8.1 and it works but I'd like a double check.

Waiting for a feedback...

-- 
Fabrizio Magni

fabrizio.magni_at_mycontinent.com

replace mycontinent with europe