Configuring Network Access

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 (NFSv3, NFSv4.1, SMB and S3).

To configure the virtual IPs, you need to create virtual IP pools (VIP pools). Virtual IP pools are ranges of IP addresses that VAST Cluster can use to listen for data traffic. All virtual IPs in a configured virtual IP pool are distributed evenly among all active CNodes or a group of CNodes. If a CNode fails, the virtual IPs 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 virtual IP pool to a specific group of CNodes. See Dedicating CNode Groups to Specific Virtual IP Pools.

Migration of virtual IPs from failed to active CNodes is automatic. It requires that gratuitous ARP is enabled on the cluster switches. Gratuitous ARP is enabled by default on most vendor switches. For the following vendors, gratuitous ARP is disabled by default:  

Clients can mount VAST Cluster views using DNS names. Every client is allocated a single virtual IP per mount. The distribution can be handled most easily using the VAST Cluster DNS server. Configuring the VAST Cluster DNS Server simplifies the configurations you need to do on your external DNS server. You can alternatively configure an external DNS server to handle all DNS forwarding to virtual IPs. With either alternative, virtual IPs are allocated in a round robin scheme. It's possible to configure multiple virtual IP pools and to set different domain names per virtual IP pool. For further information, see DNS-Based Virtual IP Distribution.

VAST Data recommends a minimum of two virtual IPs per CNode. For optimal load balancing, we encourage four virtual IPs per CNode for clusters with one CBox (four CNodes); and four or more virtual IPs per CNode for larger clusters.

When determining how many virtual IPs to configure, the following considerations apply:

You can limit a virtual IP pool to a specific group of CNodes, in order to dedicate those CNodes to a specific set of hosts or applications.

You can configure a virtual IP pool to serve a specific tenant.

CNode Port Affinity adds the ability for CNodes to be connected to multiple networks simultaneously. For example, one port can be connected to an InfiniBand network and the other to an Ethernet network, or the two ports can be connected to two different InfiniBand networks.

By default, a virtual IP pool runs on all ports on the CNodes added to the pool. If necessary, you can configure the virtual IP pool to run only on left ports or only on right ports of the CNodes.

Port membership is specified when you create or modify a virtual IP pool. See Managing Virtual IP Pools.Managing Virtual IP Pools

You can limit the set of virtual IP pools that can access a given view. This is configured in the view policy.

Yes, you can use VLAN tagging if you wish to control which virtual IP pools are accessible on specific VLANs on your data network.

VMS runs on one of the CNodes in the cluster. In the event that the CNode hosting VMS fails, VMS is moved to another CNode. Virtual IP pools have an optional setting, VMS preferred, which you can use to configure a preferred domain for VMS election. Enabling VMS preferred on a given virtual IP pool specifies that the CNodes participating in the virtual IP pool belong to a VMS-preferred domain.  

If a VMS-preferred domain is configured, then, in the event that the VMS CNode becoming unavailable, VMS moves to one of the CNodes in the VMS-preferred domain unless all CNodes in the VMS-preferred domain are offline. If all CNodes in the VMS-preferred domain are offline, VMS is started on a non VMS-preferred CNode and then moved to a VMS-preferred CNode when one is active and stable.

In clusters that have fewer than 16 CNodes, the CNode that hosts VMS can concurrently host one or more virtual IPs from virtual IP pools. In clusters with 16 or more CNodes, one CNode is dedicated to VMS. In this larger cluster case, when VMS moves to a CNode, the virtual IPs on the CNode are redistributed to other CNodes.

Therefore, with larger clusters, if a virtual IP pool is configured with a CNode group, then having VMS move to one of the CNodes in the CNode group means that the virtual IP pool loses that CNode for the time being.  

Note

VMS preferred is not supported for virtual IP pools that have a CNode group with fewer than three CNodes.