I have a client which went through a switchover practice for the first time.
After switching over to a standby box, I realized a performance issue in terms of IO write.As the result, it was decided to bump up database memory footprint for SGA and PGA since the box has enough memory.
Changes were made on spfile and new SGA was bumped up to 24GB and PGA to 4GB from total 32GB. After bouncing database, database hung in nomount and after a minute,the box was totally freezed which did not allow connection anymore.
The following was reported in Alert log :
ORA-27300: OS system dependent operation:fork failed with status: 12
ORA-27301: OS failure message: Not enough space
ORA-27302: failure occurred at: skgpspawn3
According to Oracle (Metalink note 560309.1), This could be lack of memory or improper setting of swap. Since in my case, physical memory was enough, it turned out that the issue was because of improper setting of swap. Swap needs to be set at least 0.75 times of physical RAM when memory>8GB
In my case, swap was 16GB while physical memory was 32GB which explained the case.
This issue could happen on any platform, my case was on Sun Solaris 64bit.