My question is what is the outcome when 2 clients try to connect to same VIP pool.
According to MapR documentmentation:
I just wonder why we need 2 VIP Pools.
What if Client 2 try to connect to VIP Pool A?
If Client 2 connected to VIP Pool A, then both clients would simply be accessing the cluster through the same NIC (which is fine).
The main reason for creating multiple VIP pools, is to provide multiple highly-available connections to the cluster. Each VIP pool forms a connection to one IP address that persists until the connection fails over. Suppose you had something like this:
Pool A is assigned a virtual IP address of 192.168.25.1, and Hosts 1 through 4 are part of the pool. The green arrow indicates that Pool A has established a connection to Host 1. The dotted gray lines point to other hosts that are part of the pool, available to fail over to if the connection with Host 1 fails. When a client connects to Pool A (using IP address 192.168.25.1), it is actually connecting to the cluster through Host 1. Here, all three clients are connecting to the cluster through Host 1. If additional clients connect to Pool A, they will all be connecting to the cluster through Host 1.
If you wanted to use VIPs to provide high availability access to the cluster through multiple hosts, you would need to configure additional VIP pools (each pool provides only a single connection). For example with this setup:
A client that connected to VIP Pool A would connect to the cluster through Host 1; a client connecting to VIP Pool B would connect to the cluster through Host 4. Host 2 is available as a failover for Pool A, and Host 3 is available as a failover for Pool B.
You could also create several VIP pools that each contained the same set of hosts. Each VIP could establish a connection to a different host, but still have the remaining hosts available to fail over to. For example, the diagram below looks complicated - but it's simply showing three different VIP pools that all contain the same set of 4 hosts. Pool A connects to Host 1, Pool B connects to Host 3, and Pool C connects to Host 2. If the connection to Host 1 fails, then VIP Pool A would failover its connection to any one of the other hosts in the pool.
Very detailed explanation. Thank you!
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