05-10-2017 09:18 PM
Client currently has a single server running both ERDAS Apollo and GeoMedia WebMap 16.
(I realise preference is to split Apollo and WebMap onto seperate servers)
Client would like to add a second server and use Windows Server NLB to load balance the two nodes without introducing a seperate load balance server.
Looking at the installation guide, appears there is a strong preference for a seperate load balancer and ARR for load balancing.
Has anyone successfuly applied Windows Server NLB to an ERDAS Apollo load balanced scenario?
Or should client seriously consider adding a load balancer running preferably ARR?
Any other feedback/warnings appreciated.
05-22-2017 07:50 PM
Client believes they can free up an hardware based NetScaler for seperate load balancer.
Any known issues using hardware load balancer (NetScaler)?
Any reason it wouldn't be supported?
05-22-2017 11:41 PM
In theory, you can use any load balancing software you want, but only ARR has been tested with APOLLO by the product center.
Yon can also install the load balancer on the same node than an APOLLO installation. The only thing is that you have to change to change the default port of that node for APOLLO. So, the load balancer will listen to port 80 and redirect the requests to another node or the same node but on another port.
As you mentioned, pay also attention to the services/applications that need client affinity (Geospatial Portal, ECWP v2), you can load balance the others randomly: OGC services (Core, catalogWMS, EAIM, legacy services, catalog requests, etc.).
05-23-2017 01:40 PM
Thanks Florent - useful info. For hardware or NLB load balancer, my understanding is can deal with Geospatial Portal state by using 'Microsoft's ASP.NET State Service'. That leaves ecwp v2 affinity - will put my thinking cap on.
05-24-2017 05:25 AM
I have set up an Apollo cluster with NLB. There shouldn't be a need to worry about the session state. After the initial request where the target node is determined, each subsequent requests from the same client are routed to the same server node. I.e. the node balancing is done per session, not per request.
05-24-2017 08:22 PM
Thanks Egon - useful info. I had been under the mistaken impression Windows Server NLB didn't support client affinity.
Just found out that clients netscaler hardware load balancer supports 'stickability' which seems to equate to ARR client afinity so all should be good.