Under Nginx/PHP-FPM, I can't get PHP errors logged to craft/storage/runtime/logs/phperrors.log
as they should be.
Initially, errors weren't logging anywhere, but I discovered I needed:
catch_workers_output = yes
in our PHP-FPM config.
Errors are now logging to /var/log/php7.0-fpm.log
, but not to Craft's custom location.