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High Availability in Hurricane Alley Multi-site multi-node CAS Deep in the Heart of Texas Srinivas Varadaraj & Bill Thompson Jasig Sakai Conference1.

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Presentation on theme: "High Availability in Hurricane Alley Multi-site multi-node CAS Deep in the Heart of Texas Srinivas Varadaraj & Bill Thompson Jasig Sakai Conference1."— Presentation transcript:

1 High Availability in Hurricane Alley Multi-site multi-node CAS Deep in the Heart of Texas Srinivas Varadaraj & Bill Thompson Jasig Sakai Conference1

2 Agenda 1.Strategy 2.Technical requirements 3.Constraints 4.Stuff at hand 5.Architectural decisions 6.Cluster & production architecture 7.Challenges and solutions 8.Multi-site routing 9.Production experiences 10.Questions & Comments Jasig Sakai Conference2

3 Strategic requirements Single Identity Single Sign On/ Single Sign Off Maximize self service tools Improved user experience Jasig Sakai Conference3

4 Technical requirements Application Compatibility High Availability Rolling maintenance Transparency Scalability AD integration Customization(branding) Jasig Sakai Conference4

5 Constraints Limited budget, use existing resources. – Power in the datacenters – Single internet – High latency connectivity Limited in-house development & experience – Stay close to release code Aggressive timeframe Jasig Sakai Conference5

6 Stuff we had at hand SAN infrastructure with replication to DR VM clusters Site-to-site VPN based connectivity to DR F5 loadbalancers Dedicated firewalls Opportunity Jasig Sakai Conference6

7 Decisions ! Decisions ! Decisions ! Virtual Machines SAN based storage The great ticket registry debate To replicate tickets or NOT ! Building by cloning “Appliance” like SSL Local vs Offloading Cluster VS Standalone application servers Timeout ! Jasig Sakai Conference7

8 Cluster components Jasig Sakai Conference8

9 Final Architecture Jasig Sakai Conference9

10 “Holy troubles, Batman!” SSL offloading – Tomcat offloading workaround Authentication and Validation persistence – User and application can go to either site. – Enter site identifiers Multi-site ticket replication. – Latency in WAN Algorithm usage in phpCAS clients and Java CAS clients Slow performance of mod_auth_cas on VMs Jasig Sakai Conference10

11 Routing logic HTTP_REQUEST HTTP_REQUST_DATA HTTP_RESPONSE Jasig Sakai Conference11

12 HTTP_REQUEST(Request from the client) HTTP_REQUEST{ 1)Grab header length to determine payload size 2)If both sites are down, redirect to a branded service unavailable page 3) If URI has siteID of other site and other site is up, route to other site 4) Otherwise default route to local site } Jasig Sakai Conference12

13 HTTP_REQUEST_DATA(Payload manipulation) HTTP_REQUEST_DATA{ 1)Grab from payload, this may contain siteID 2) if we have a siteID of the other side { If the siteID is Loadbalancer introduced { blank the loadbalancer extension } Route to other side else { if we have a siteID of the local side { If the siteID is Loadbalancer introduced { blank the loadbalancer extension } Route to local side } Jasig Sakai Conference13

14 HTTP_RESPONSE(Response from the server) HTTP_RESPONSE{ 1)Grab server’s response headers 2) If SiteID is not in the response header { Introduce a loadbalancer siteID to compensate for java CAS client } Release HTTP to client } Jasig Sakai Conference14

15 Jasig Sakai Conference15

16 Experiences in Production Approx. 8 months in production 7 Applications in production 10 in development Survived two power outages at DR Survived multiple internet outages Successful rolling upgrades to MySQL & CAS Flow based redesign. LPPE Re-visit ticket registry Jasig Sakai Conference16

17 Questions/Comments Credits: – CAS developers and community – F5 & F5 devcentral – Unicon – LU & Txstate Thank you for your time !! Contacts: – Sri: – Bill: Jasig Sakai Conference17


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