Solved

Is it possible to have a redundant cache server

Posted on 2012-03-14
2
688 Views
Last Modified: 2013-11-16
A cache server in Linux is typically used in front of a cluster. When a server in a cluster drop out, the cache server will determine which server in the cluster to use.
Question1:
Is it possible to use 2 cache servers in Linux (redundancy)


In Lotus Domino a cache server is called a ICM (internet cluster manager). It is a manager running on the Domino server.  Well it is not a cache, but is is used in the same manner as a Linux cluster front.
Question2:
Is it possible to use 2 ICMs in front of a Domino web server running in a Domino cluster.

It should not be possible, but the Domino Administrator manual suggest a solution. It seems pretty weered, and difficult to understand the thinking behind such a solution. Study the pictures below, and tell me how it is possible to have 2 ICMs?

From the Lotus Domino Administrator database:
Example of multiple ICMs-outside a clsuterExample of multiple ICMs inside a cluster
0
Comment
Question by:tbruheim1967
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 4

Accepted Solution

by:
cohalex earned 125 total points
ID: 37720347
Related to question 2):

I can imagine that you would need multiple ICM servers for load balancing, in case one ICM server isn't enough to serve all of your incoming requests.
In this case, you could have an A record in your DNS system for each ICM server, resolving the same address to different ICM host names. If your DNS service is capable of round robin fetching, you have your basic load balancing done.
Round robin enabled DNS systems return all A records for a given address (the order of the entries being scrambled for each serving).

As to the high availability benefit described in the Admin manual, you would have to rely on the HTTP client to actually try the next A record in case it gets no reply from (most probably) the first one it tried ..
Are browsers actually doing that ? Seems so, check this thread:
http://webmasters.stackexchange.com/questions/10927/using-multiple-a-records-for-my-domain-do-web-browsers-ever-try-more-than-one
0
 

Author Closing Comment

by:tbruheim1967
ID: 37720976
Awesome. Great answer. I did not have knowledge about the browser stuff you told me. Your information about DNS was also partially new stuff for me. Thank you very much.
0

Featured Post

Instantly Create Instructional Tutorials

Contextual Guidance at the moment of need helps your employees adopt to new software or processes instantly. Boost knowledge retention and employee engagement step-by-step with one easy solution.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Quality of Service (QoS) options are nearly endless when it comes to networks today. This article is merely one example of how it can be handled in a hub-n-spoke design using a 3-tier configuration.
The use of stolen credentials is a hot commodity this year allowing threat actors to move laterally within the network in order to avoid breach detection.
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
Michael from AdRem Software explains how to view the most utilized and worst performing nodes in your network, by accessing the Top Charts view in NetCrunch network monitor (https://www.adremsoft.com/). Top Charts is a view in which you can set seveā€¦

717 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question