i have two servers (one mysql db server, one client server) with direct ethernet link. The "remote" access used to be lighting fast (neglectable latency for query), no matter using IP addr or DNS.
to fine tune the performance, i modified my.cnf (redhat, /etc/my.cnf) [mysqld] category on the db server (by changing the key and innodb buffer related size). since the test result was not good enough, i changed my.cnf back to its default status.
however since then, it became extremely slow to establish the connection to the db server from remote (local access seems fine). any idea what's the reason behind?
ps:
- once connected, remote query seems working as fast as before. it's just slow to establish the connection.
- the common DNS issue seems not valid here, given it cannot explain (a) why the connection through DNS was fast; (b) why [mysqld] changes in key/innodb buffer size would affect the DNS, even with my.cnf changed back to its default status; (c) connection establishment became slow through either IP or DSN after the change/change-back of my.cnf
UPDATE:
After hours of struggling, i restarted the db server and now it seems my.cnf functions as expected...