Hi, As a Java developer, I'd say that adding more RAM to a JVM may probably incur longer GC pauses while on the other hand I'd trust Varnish to gracefully scale with more RAM and CPU. Please do not interpret that as a bad opinion on modern JVMs or Tomcat, you'd be very wrong :-)
Architecture-wise, my first advice would be to think about removing your httpd servers and put your Tomcat instances right behind Varnish. Unless you need it for something other than a reverse proxy for your webapp of course. Regarding solutions a and b, my intuition goes towards b. Instead of pinning one apache/tomcat pair for one Varnish instance, I'd put them all in a director. If one backend is sick, Varnish can try again with a healthy backend. Performance-wise, measure, don't guess. Cheers, Dridi On Wed, Aug 20, 2014 at 4:02 PM, Hernán Marsili <[email protected]> wrote: > Hi, > > > A couple of month ago I asked a question here regarding the best VARNISH > architecture for a high traffic site. We then do some testing and we are > still unsure of the best scenario, so I ask again with a little more > information. > > We have a 40.000 concurrent users sites. This is handled by 5 boxes. On each > box we have TOMCAT, APACHE and VARNISH using malloc. > > What we want to determine, is the impact on each server VARNISH makes, > mostly at a 'connections' level and determine if is best to: > > a) growth adding same kind of servers (boxes with all 3 services) > b) separete Varnish from the boxes and have, for example, 2 varnishes > balacing with 4 backend servers > > On the b scenario, we can assign more memory to the TOMCAT and handle more > load. The CACHE HIT RATE is not an issue, since all the boxes have a very > high hitrate. > > Any advice on this matter will be appreciated. We are inclining now for the > A option. > > _______________________________________________ > varnish-misc mailing list > [email protected] > https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc _______________________________________________ varnish-misc mailing list [email protected] https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
