Is there any function in domino for failover on webmail? We have a domino cluster and failover is working on Notes clients if one server is down…
Is it possible to do the same with webmail?
We have two dns names for reaching the domino servers externally…
Subject: Examples of Load Balancer configs for iNotes
Examples from Lotusphere, using IBM Websphere Edge Components for Load Balancing and Reverse Proxy
Subject: load balancer
As it is right now we have a internet load balancer and can conf it in there. It’s maybe the best solution…
Subject: Failover for Webmail
The failover models for Notes Clients accessing Domino Servers via the Notes protocol and Internet applications such as HTTP are very different:
Notes clients automatically maintain a list of servers which have replicas of databases and switch to another server with one server fails. This is what is working well for you now.
The model for Internet services is to put multiple servers that offer the same service behind a network sprayer. The sprayer is then configured in one of the following ways to select a server for each incoming connection. So, if one of the servers fails another server can provide the service.
Sprayer can randomly select one of the servers to evenly distribute the load. Once a client machine connects to a specific server, the sprayer can be configured for “sticky” connections so that context for sessions is retained.
Sprayer can be configured to select a specific server for specific urls and switch to another server if the first in not available.
If you have only two servers with mail file replicas for all users on both servers, then either of these two options would work well for you. Network sprayers (also called load balancers) can be purchased as appliances or software for a modest server. They are fairly low cost. The end users use the name / IP address of the srayer to access their mail files.
If however, you have replicas for each user on only some of your servers, neither technique 1 or 2 above will work well for you. You could:
Configure mail files on pairs of servers and have a sprayer for each pair - thus techniques 1 and 2 above would work well.
Some sprayers / load balancers support user written callouts to select the target server. If the callout reported which servers had a mail file replica for the mail file named in the url, this would work.
IBM makes available a component called the Internet Cluster Manager. It performs the selection algorithm, but is not a proxy like all sprayers are. i.e. A proxy stays in the connection and passes packets back and forth between the client and the selected server so that the client only ever knows the name / address of the proxy itself. The ICM instead returns a referral to the web browser naming the server on which the replica exists. However, if that server fails, the web browser must re-attempt the connection on the original address of the ICM, not the returned referral address. Because of this most customers prefer the use of a sprayer.