VAST Cluster listens for requests on IP endpoints that are virtual, and therefore called Virtual IPs (VIPs). These endpoints are for all data traffic for all protocols (currently NFS and S3).
To configure the VIPs, you need to create VIP pools. VIP pools are ranges of IP addresses that VAST Cluster can use to listen for data traffic. All VIPs in a configured VIP pool are distributed evenly among all active CNodes or a group of CNodes. If a CNode fails, the VIPs assigned to it are automatically moved to other active CNodes, ensuring that clients can continue to connect to stable IP addresses.
This model provides for load balancing and transparent failover among the CNodes.
*You can choose to limit a VIP pool to a specific group of CNodes. See Dedicating CNode Groups to Specific VIP Pools.
Load balancing can be set up most easily by configuring the VAST Cluster DNS server or an external DNS server. See DNS-Based Load Balancing.
VAST Data recommends a minimum of two VIPs per CNode. For optimal load balancing, we encourage four VIPs per CNode for clusters with one Cbox (four CNodes); and four or more VIPs per CNode for larger clusters.
When determining how many VIPs to configure, the following considerations apply:
Since each CNode has two ports listening for data traffic, there should be at least two VIPs available to each CNode.
It is desirable for the number of VIPs to be evenly divisible by the number of CNodes. That way when all CNodes are running, VIPs will be spread evenly.
More VIPs improve balancing on failure. In case a CNode with only one VIP were to fail, the one VIP for that node would be moved to one active CNode, doubling the work of that CNode. If the failed CNode had more than one VIP, each VIP could be moved to a different active CNode. Therefore, the more VIPs there are per CNode, the better the system is able to balance load on failure. With one VIP per CNode, 100% of that load is moved to one other CNode. With two VIPs, 50% is moved to one and 50% to another. With three VIPs, the ratio is 33%/33%/33%, and so on.
If the cluster has four or more CBoxes, the management CNode (the CNode that runs VMS) is not assigned VIPs.
You can limit a VIP pool to a specific group of CNodes, in order to dedicate those CNodes to a specific set of hosts or applications.
Yes, you can use VLAN tagging if you wish to control which VIP pools are accessible on specific VLANs on your data network.