<div dir="ltr">Dear Amupama,<div><br></div><div>Just my two cents, as long as you only had single physical server to contain tomcat and pgpool, then option 1 is the best one.</div><div>Since HA (High Availability) conceptually counts about Physical Server Disaster avoidance. then separating 2 PgPool instances but still share resources with other apps like Tomcat is not meet the ideal condition of HA.</div>
<div><br></div><div>Regards, </div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Feb 20, 2014 at 7:18 AM, Anupama Ramaswamy <span dir="ltr"><<a href="mailto:anumr_0123@yahoo.com" target="_blank">anumr_0123@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-size:12pt;font-family:HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif"><div>
My current setup involves a Tomcat Web Application on a Postgres backend. I need to have a load balanced / highly available application. <span style="background-color:transparent">So I have setup postgres with streaming replication and 2 Tomcat server load balanced in a cluster. I have pgpool to load balance the postgres read-only queries.</span></div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif"><br></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
I do not want pgpool to be a single
point of failure. So I need to setup 2 pgpool instances. <span style="background-color:transparent">Here is my question.</span></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
Of the 2 configurations below, which is recommended and why ?</div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
<br></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">1) Application server = Tomcat + pgpool ---> Each tomcat connects to the local instance of pgpool which load balances against the 2 DB servers. So when one of the
app servers is down, the other will continue to operate.</div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
<br></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">2) Application Server 1 = Tomcat (active) + active PgPool. Web app connects to local instance of PGpool (through Virtual IP)</div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">Application Server 2 = Tomcat (active) + passive PgPool. The web app connects to remote instance of pgpool (through Virtual IP). The local instance is configured as "Other
PgPool" with a watchdog. This takes over only if the first instance goes down.</div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
<br></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">Not able to figure out if the first approach has any pitfalls - 2 disparate pgpools supporting 2 front-ends will cause any inconsistencies. Any help/ suggestions welcome.</div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif"><br></div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">
Regards,</div><div style="font-style:normal;font-size:16px;background-color:transparent;font-family:HelveticaNeue,'Helvetica Neue',Helvetica,Arial,'Lucida Grande',sans-serif">Anupama.</div><div><br></div></div>
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