Keep in mind the following networking and name server considerations:
- Minimize disruption by suspending nodes in preparation for planned maintenance and resuming them after maintenance is complete
- Leverage the groupnet feature to enhance multitenancy and DNS delegation, where desirable.
- Ensure traffic flows through the right interface by tracing routes. Leverage OneFS Source-Based Routing (SBR) feature to keep traffic on wanted paths.
- If you have firewalls, ensure that the appropriate ports are open. For example, for the DNS service, if you open UDP port 53, ensure that TCP port 53 is also open.
- The client never sends a DNS request directly to the cluster. Instead, the site nameservers handle DNS requests from clients and route the requests appropriately.
- In order to successfully distribute IP addresses, the OneFS SmartConnect DNS delegation server answers DNS queries with a time-to-live (TTL) of 0 so that the answer is not cached. Certain DNS servers (particularly Windows DNS Servers) will fix the value to one second. If many clients request an address within the same second, all of them receive the same address. If you encounter this problem, you might have to use a different DNS server, such as BIND.
- Certain clients perform DNS caching and might not connect to the node with the lowest load if they make multiple connections within the lifetime of the cached address.
- The site DNS servers must be able to communicate with the node that is currently hosting the SmartConnect service. That node is the node with the lowest logical node number (LNN) with an active interface in the subnet that contains the SSIP address. This behavior cannot be modified.
- Connection policies other than round robin are sampled every 10 seconds. The CPU policy is sampled every 5 seconds. If multiple requests are received during the same sampling interval, SmartConnect will attempt to balance these connections by estimating or measuring the additional load.
For more information, see the OneFS SmartConnect white paper.