ORA-12631: Username retrieval failed

After Windows 2008 R2 patches were applied, SQL*Plus connections failed with ORA-12631. I couldn't find a match on the Oracle support site, so I had to do more digging. By enabling SQL Tracing on the server side, I tracked down OS error messages that matched in KB4480970 and KB4480960. Microsoft has a fix, KB4487345, which worked for us.


Windows Large Pages vs LOCK_SGA

Large pages are important for performance of instances with large SGAs, and the mixed mode of allocation in Windows is a good idea. Unfortunately, it has been poorly implemented, leaving Oracle DBAs without an ideal configuration option.