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When we talk about the Citrix Delivery Center, we are talking about an end-to-end application delivery infrastructure solution. A solution which represents a family of Citrix product lines: Citrix XenServer, Citrix XenApp, Citrix NetScaler and Citrix XenDesktop. It also represents products that add integrated security, management and networking functions, products such as: Citrix Access Gateway, Citrix Branch Repeater and Citrix Desktop Receiver. Overall, the Citrix Delivery Center gives customers the power to adopt virtualization that meets their specific requirements. Customers can choose to optimize delivery of their Web Applications, Windows Applications, Desktop Delivery, Data Center Optimization - individually or in combination. How about all of them?
Now according to a recent Forrester study "49% of enterprises surveyed that are implementing or interested in virtualization solutions indicate that improving disaster recovery/business continuity continues to be a very important motivation for adoption". So what better way to pique their virtualization/business continuity interest than by demonstrating an end-to-end Citrix and Marathon combined solution onsite at the world's largest business software company SAP.
Recently the Citrix Worldwide Consulting Solutions and Business Development teams did just that. We built and demonstrated a Proof of Concept environment that delivered a highly available and virtualized SAP infrastructure using a complete Citrix Delivery Center solution. Within a two week period, the Citrix, Marathon, and SAP teams built and demonstrated a complete Proof of Concept environment. For a quick project overview please refer the data sheet here.
So how did we do it....First we virtualized every Citrix Delivery Center component and the backend SAP NetWeaver application servers using Citrix XenServer. Then we showcased what a remote SAP NetWeaver user would experience accessing the SAP NetWeaver Portal via Citrix Delivery Center while focusing on the high availability/fault tolerant solutions Citrix and Marathon provide. Finally, we simulated a complete failure in the primary site and used the combined NetScaler Global Server Load Balancing feature in conjunction with Marathon's everRun DR product to failover SAP to a secondary data center.
Let's go through the steps that describe the demonstrated user experience:
- Remote SAP NetWeaver Portal user securely connects to the SSL VPN provided by Citrix Access Gateway Enterprise Edition.
- All connections from the remote user client are accelerated using Citrix Branch Repeater Plug-in.
- Remote user is seamlessly presented with the Citrix Web Interface website with on-demand access to virtual desktops, applications, bookmarks and other corporate resources.
- From the Citrix Web Interface page, the remote user launches a virtual Windows XP desktop hosted by Citrix XenDesktop. This desktop is a private virtual image of Windows XP running within a secure data center and maintained from a centralized Windows XP image provisioned dynamically with Citrix Provisioning Server.
- From the secure virtual Windows XP desktop, the remote user launches a published SAP NetWeaver Portal delivered by Citrix XenApp. The published NetWeaver Portal application is separated from the virtual Windows XP Operating System allowing optimal user performance.
- As the remote user navigates the application, all SAP NetWeaver Portal connections pass through a Citrix NetScaler configured to optimize SAP NetWeaver Portal application delivery.
We also demonstrated the following high availability and recoverability solutions provided by Citrix XenServer and Marathon everRun software:
- Level 1: XenServer delivers out-of-the-box high availability, including cost-effective core failover, recovery and restart capabilities for SAP applications running in the virtual environment.
- Level 2: Marathon everRun VM delivers high availability of component-level fault tolerance, eliminating downtime caused by I/O component failures and guaranteeing recovery from system failures.
- Level 3: Marathon everRun VM's Lockstep Technology delivers continuous availability from system-level fault tolerance, eliminating data loss, downtime and transaction loss.
- Disaster Recovery: Marathon everRun DR provides a robust and flexible remote disaster recovery solution providing automated and reliable long-distance protection for critical data and applications, in this case, SAP.
Each piece of the demonstration was broken down into small video segments for this blog. The first video features the Citrix Delivery Center environment for SAP from top to bottom including the remote user login, virtual desktop access, and SAP NetWeaver Portal launch. Then a complete site failure is simulated and the secondary site recovery is shown using Marathon's everRun DR solution with Citrix NetScaler's Global Server Load Balancing feature.
Stay tuned for a detailed reference architecture and video blogs on different High Availability scenarios including everRun VM also demonstrated at SAP Co-Innovation Lab.
Here's the video:
Load Balancing Auto-Configuration for SAP using Workflow Studio and NetScaler
At the tail end of our certification process at SAP, Citrix engaged in a unique opportunity to make use of the SAP APIs, using Workflow Studio to auto-configure the Citrix NetScaler for Load Balancing. The way it works is, Workflow Studio polls the SAP API, reads the response, and then based on the results in the response, configures the NetScaler Load Balancing groups that map directly to the SAP servers running in the server farm.
SAP has a community group dedicated to the development of their APIs, please reference the latest blog post Catching Up with Deployment and Operations Automation, describes the SAP APIs.
The SAP Community Definition Group (CDG) - titled "PCDG 97 NetWeaver Infrastructure APIs for Network Solutions" - is focused on automation of network-application integrated configuration and operation. As the group title implies, the SAP NetWeaver technology platform includes APIs, which are used by the NetScaler ADCs (load balancers) to auto-configure themselves as proxies for multi-instance SAP application systems. Using Citrix Workflow Studio, the SAP APIs are polled on a regular basis so that the NetScaler ADCs can react to SAP application instance changes during production runtime.
If another application instance is brought up, let's say for providing more computing capacity for an increasing end-user load, or if an instance is brought down temporarily for maintenance, Workflow Studio communicates with the NetScaler ADC to adjust load balancing automatically without any manual administrator intervention. There is no more wait, or lengthy change management required to provision applications.
Workflow Studio, NetScaler and SAP API Use Cases:
Use Case 1: (auto-configure new SAP services).
Workflow Studio sends a URL request to the SAP Message Server, and receives a response. Workflow Studio parse's the response, looking for specific SAP generated patterns. WFS then uses this information to configure a Load Balancing Virtual Server inside of the Citrix NetScaler.
Use Case 2: (dynamic configuration).
Workflow Studio repeatedly queries the SAP API. WFS studio can determine hostnames, ip addresses, port numbers, and whether an SAP server is coming online or going down. When a SAP server comes online/goes down - WFS detects this change, and then takes action on the Citrix NetScaler, to add/remove the SAP service from the Load Balancing group - automatically.
Use Case 3: (graceful shutdown).
Workflow Studio queries the SAP API, determines a SAP server is going down, and based on the response, waits until all existing sessions have been retired, before removing the server from the Load Balancing group . During the shutdown period, no new sessions are added to that SAP server, providing a graceful shutdown of the SAP service. This way, there are no TCP resets sent to existing sessions. New logins are routed to a different server.
Read the SAP article here.
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