How to calculate production configuration values with msm

[rdp]

Hi Martin

First of all thank you for msm .It makes thing so easy.

I have been working on msm for last two weeks.

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

I will be setting memcache nodes of individual servers seperate from tomcats so each memcache node will have a dedicated server

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"

2) How many memcache nodes will be ideal for 6 tomcats. Is there any rule I can follow to decide number of memcache node ?

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

4) Will sticky option give better performance compared to non sticky ? 

   Is the reason for stickys better performance that ,as we avoid hitting memcache in sticky option and use session from local tomcat and only hit  memcached tomcat is down 

5) 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

Regards,