Hi, > I am using memcache for tomcat websession clusering with help of memcached > session manager library .I got it working for sticky and non sticky for 2 > tomcats with 2 memcache nodes > > I need to implement session replication for 6 tomcat servers in production > > I would like to know how the configuration values for production memcache > nodes should be evaluated > > > > 1) -m config value > > - As I understand "-m" will be amount of memory allocate to memcache node > to hold session. When this is full LRU session will be removed and will be > unavailable. > - Lets say if one tomcat server has 200 session during peak traffic and > average session size in 2kb > - Are below calculations correct to decide value to "-m" parameter for a > memcache node > > (number of tomcats) X (number of session during peak) X (average session > size) > > 6 X 200 X 2kb = 24 MB > > to be safe i will make this double which is 48 MB > > Are there any rules you follow when assigning value "-m"
48MB is less than the default, even. You could just leave it there. There's some overhead per item: 48-56 bytes for headers, plus the key, plus a few other things. So it's not just 2k each, more like 2.1k depending on how long your keys are. Either way, that's a tiny amount of memory. > > 2) How many memcache nodes will be ideal for 6 tomcats. Is there any rule I > can follow to decide number of memcache node ? Keep enougn nodes so you can tolerate one failing. You'll have a better idea of this once you see your load, but I have a feeling your memcached's will be very idle. > 3) Number of connection allowed per memcached nodes - How can i determine > this ? Is it safe to just make it > > (number of tomcat) X (number of session during peak traffic ) > > 6 X 200 = 1200 and to be safe I will double this so 2400 > > So 2400 connections per memcache node > > Are there any rules you follow when assigning value number of connection > on memcache node Not really. Each connection structure uses some memory, so just don't set it super high. > 4) Is there a performance impact if memcache nodes sit on different server > than tomcat server . Will performance be better if primany memcache node and > tomcat are on same server Having nodes on a different server is how memcached was designed to be used. have fun, -Dormando -- --- You received this message because you are subscribed to the Google Groups "memcached" group. To unsubscribe from this group and stop receiving emails from it, send an email to memcached+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
