MinSeeder and Quorum Size - how exactly do they differ

[Sanath Kumar Kruthiventi]

Not able to figure out so reaching out for help. Minimum seeder count and the Quorum size seems stepping on each other somehow, but couldn't understand how exactly. Both definitions say that the cluster will not start if either counts doesn't match. So why exactly we need both Sounds something like Quorum size can be

[Vaz Balasingham]

You are right:MinSeeder is fundamentally about ensuring you have enough copies of the data to ensure nothing is lost in the event a server is lost, and Quorum size is about recovery - in the context of BWAgents use of the data grid it would make sense for QuorumSize >= MinSeeder as you will not have multiple BWAgent Servers on the same Machine.

The common use of the QuorumSize property is more appropriate in the context of ActiveSpaces where it is possible to have multiple Seeders (Servers) on the same (Machine). I.e you could have a configuration of 4Seeders on 2 Machines - in this case you would want QuorumSize = 3 to ensure that once the DataGridis ready you will have a copy of the data on each Machine.

[Sanath Kumar Kruthiventi]

 Vaz, thanks a ton for addressing my query, its delightful to see the response. My apologies in delay to get back.From the BusinessWorks perspective, from the definitions extracted on minSeederCount property from documentation link I posted earlier,It determines the minimum number of bw agents that are configured to run in the Server agent role, for the bwadmin cluster to function.andThis property determines the minimum number of bwagents that are configured as server in the bwagent network.For example, if five bwagents are configured as server with a minSeederCount=3, then two of the bwagents can be stopped without impacting the bwagent network.so we can interpret that this property highlights the minimum number of server nodes (seeders) required to start the agent cluster. And on the Quorum size notes reads asThis value should be set to the number of bwagents configured as server. For example, if we configure five bwagents to run as servers with a quorum of "5", the first four bwagents do not start until the fifth bwagent is also started.Means agent cluster will not start. So, setting minSeederCount between 1 and 4 in above case is insignificant since the quorumSize should be set to numer of bwagents configured as server, rightSo in any case, if minSeederCount and quorumSize are not exactly equal, the agent cluster will never start, right then why we need two properties here

 Please clarify, thanks in advance again !! 

[Marcell Zoltn Szalontay]

What Vaz wrote you its correct, maybe I can show you better with an example why:

Let's imagine that we have a network with 16 bwagents configured as server. In this case the minSeederCount as the definition says: Floor(n/2)+1, where n>2 and n is the number of the bwagents configured as server. In our case its (16/2)+1=9.

The quorum size as Vaz mentioned as well has to be equal or larger than the minSeederCount and it will be less or equal as the actual numbers of server bwagents: [Number of server bwagents >= quorum size >= minSeederCount] in our case its 16>= quorum size >= 9.

It means that in the bwagent.ini you can set the quorum size, and then if you will restart you need at least as much active server bwagent what you set in the quorum size otherwise it wont start up - the possible values to set the quorum size it between 9 to 16.

I hope it helps.