On Wed, May 30, 2018 at 02:01:05PM +0500, Muhammad Yousuf Khan wrote: > Dear Sir, > > As you have mentioned earlier below. > > wtprd0X (search for ‘wtprd0’) - these are front end web server nodes for an > HA cluster (uses HAProxy in pfSense) > wtsqlprd01-3 (search for wtsql) - these are 3 MySQL servers for the backend > of a site in HA > > I can understand the purpose of 3 frontends but how 3 Mysqls are designed > are they replicating to each other get updated or or is this a enterprise > cluster. > Cluster in a sense where you are running multple nodes of MYSQL but > application sees only one and if any of the instance goes down the other > stands for backup. is it like. > > how does the 3 MYsql stack works. ? >
There's lots of information here: https://mariadb.com/blog-tags/high-availability The basic options for databases are: - single write master, multiple read-only replicas - single write which is also single read, with a standby replica that can be substituted in case of a disaster - multiple read/write replicas available simultaneously, but performance is often slower because they all need to coordinate potential conflicts - multiple read/write replicas with "sharding", so conflicts are less likely - and then there are combinations of the above. The information you have given is insufficient to tell which scenario is happening. -dsr-
