Question
SedgwickCMS
US
Last activity: 23 Feb 2016 22:00 EST
high availability in conjunction with load balancer (with 2 nodes behind the load balancer), do we really need to setup the load balancer with sticky session configuration?
We are actually going towards high availability direction.
1. Our production instance had load balancer with 2 nodes behind the load balancer.
2. When our internal team setup that load balancer, we requested them to setup with sticky session
3. https://pdn.pega.com/performance/load-balancing-a-multi-node-cluster
4. Since we are going towards high availability, passivation setup set up in pega through (database/share didrive)
Someone told me that sticky session needs to be switch off, when we have the capability of passivation etc. on the pega side.
But my understanding is different that we need sticky session is needed basing on the articles i have gone through.
1. Can somebody confirm that sticky session in F5 load balancer is needed or not in conjunction with high availability?
2. Also it would be better to explain how they are tied together and the purpose technically
Thanks
Accepted Solution
Pegasystems Inc.
US
Thanks for the quick response and we are using Tomcat. - Ah, no JSESSION to speak of... Good.
In the first statement we said that sticky session is needed for session affinity.
But I am little bit confused with statement "HA requires that you delete the "sticky" cookie that the F5 uses so you break affinity when you passivate that requestor"
1. If I have 2 nodes and when i quiesce on 1st node, considering that I have sticky session in F5 load balancer in place, the new requests will go to 2nd node right ?
To keep it simple, i can keep my current F5 load balancer setup with stick sessions as is right ? and can achieve high availability with other set of configurations from Pega right?
F5 Should not have to change - how you destroy the cookie within PRPC is what makes this work. You may need to do something at the Tomcat level (like remove keepalive.html or whatever the F5 uses to probe "alive" that makes it send traffic to it - might be slightly creative.
Is there any deviation in my understanding, please let me know
You're good, check out https://pdn.pega.com/documents/pega-72-high-availability-guide
Best Regards, Dean
Pegasystems Inc.
US
Greetings,
Sticky is needed - you must have session affinity.
"Sticky" affinity is used to ensure that your requests go to the same JVM instance (session) - Your requestor is only active in a single JVM - hence you need all following http requests to hit the same instance.
HA requires that you delete the "sticky" cookie that the F5 uses so you break affinity when you passivate that requestor and when that user hits the load balancer again, (hopefully) the load balancer has an idea that the node is no longer taking connections (different ways to do it) and your users get routed to different JVMs and become 'sticky' to those.
If you have WebSphere IHS load balancing (usually any shop using WAS will) - that will also have to either be disabled - or you will need to remove the jsession cookie too.
Best Regards,
Dean
SedgwickCMS
US
Thanks for the quick response and we are using Tomcat.
In the first statement we said that sticky session is needed for session affinity.
But I am little bit confused with statement "HA requires that you delete the "sticky" cookie that the F5 uses so you break affinity when you passivate that requestor"
1. If I have 2 nodes and when i quiesce on 1st node, considering that I have sticky session in F5 load balancer in place, the new requests will go to 2nd node right ?
To keep it simple, i can keep my current F5 load balancer setup with stick sessions as is right ? and can achieve high availability with other set of configurations from Pega right?
Is there any deviation in my understanding, please let me know
-Thanks
Raj
Pegasystems Inc.
US
Refer to this guide for F5 setup and more: https://pdn.pega.com/documents/pega-72-high-availability-guide If you have any feedbacks/comments on the guide, please report to pega.
Accepted Solution
Pegasystems Inc.
US
Thanks for the quick response and we are using Tomcat. - Ah, no JSESSION to speak of... Good.
In the first statement we said that sticky session is needed for session affinity.
But I am little bit confused with statement "HA requires that you delete the "sticky" cookie that the F5 uses so you break affinity when you passivate that requestor"
1. If I have 2 nodes and when i quiesce on 1st node, considering that I have sticky session in F5 load balancer in place, the new requests will go to 2nd node right ?
To keep it simple, i can keep my current F5 load balancer setup with stick sessions as is right ? and can achieve high availability with other set of configurations from Pega right?
F5 Should not have to change - how you destroy the cookie within PRPC is what makes this work. You may need to do something at the Tomcat level (like remove keepalive.html or whatever the F5 uses to probe "alive" that makes it send traffic to it - might be slightly creative.
Is there any deviation in my understanding, please let me know
You're good, check out https://pdn.pega.com/documents/pega-72-high-availability-guide
Best Regards, Dean