I hava a db server (mysql) in my web application, it include 550 tables and about 100000 rows in each table. Now, I want to change the db server to postgresql and construct a HA environment. I have two 2U servers to build postgresql server (one is master, the other is slave), and two 1U servers for any purpose about the ha environment. And I expect to use the FreeBSD as the operation system. My request is, when a server fail (no matter the master or slave), the web server can still access (read/write) the database correctly. I have three ideas about the HA environment, does anyone give me some advices? Or guide me to learn more advanced ideas. Thanks. :) First idea: I install the pgpool on each web server (the web server farm include 16 web servers), and configure the pgpool as replication mode. The web application (written by php) access to the db server through the local pgpool daemon. The idea sounds a little unusual, dose it seems workable? I just use very simple sql statment in the web application, no any complex statment. Second idea: I install the pgpool and linux-ha on the two 1U server, and configure the pgpool as replication mode. The web application access to the db server through the pgpool daemon. Third idea: I install the Slony-I, linux-ha and postgresql on the same server of the two 2U servers. The web application access to the db server directly and without pgpool. sincerely, proace
