NetWorker: NDMP sessions connect to single PowerScale node due to DNS caching

NetWorker NDMP backup sessions consistently connect to a single PowerScale node instead of distributing load across multiple available nodes. 
All NDMP sessions show the same IP address in the backup logs, even though the PowerScale cluster has multiple IP addresses configured in the SmartConnect zone.
The storage node resolves to a single IP address for all NDMP connections. 

The storage node consistently resolves to a single PowerScale IP address due to DNS caching in NetWorker and local hosts file entries. NetWorker caches DNS entries for 30 minutes by default, which prevents proper SmartConnect round-robin resolution. The storage node may also have PowerScale IP addresses in the local hosts file, which overrides DNS resolution.

Perform the following steps to enable proper SmartConnect load balancing:

1. Verify the NetWorker client resource uses the SmartConnect fully qualified domain name (FQDN) instead of individual node IP addresses.
2. Remove PowerScale IP addresses from the NetWorker server and storage node hosts files:

• • Linux: /etc/hosts
  • Windows: C:\Windows\System32\drivers\etc\hosts

3. Flush the NetWorker DNS cache by running the following commands on the NetWorker server:
   • Run dbgcommand -n nsrd PrintDnsCache=1
   • Run dbgcommand -n nsrd FlushDNSCache=9
   • Alternatively, the above commands can be run against a PID instead of process name: dbgcommand -p <PID> <options>. For more info, see: NetWorker: Debug information levels
4. Enable reverse DNS lookup by creating an empty file named enable_rdns_lookup in the NetWorker debug directory:

• • Linux: /nsr/debug/enable_rdns_lookup
  • Windows (Default): C:\Program Files\EMC NetWorker\nsr\debug\enable_rdns_lookup

5. Verify the PowerScale NDMP Data Management Agent (DMA) setting is configured as emc.
6. Confirm the SmartConnect zone uses Round Robin load balancing policy
7. Restart NetWorker services after making configuration changes:

• • Linux: systemctl restart networker
  • Windows (PowerShell): net stop nsrexecd /y ; net start nsrd
    • If the NetWorker Management Console (NMC) is installed on the NetWorker server, you must start it separately: net start gstd

After implementing these changes, monitor the backup logs to verify that different IP addresses are used for NDMP connections across the PowerScale cluster.