Ndmpcopy run via SSH consistently aborts after a fixed amount of time

Applies to

• ONTAP 9
• NDMPcopy
• DumpToNull

Issue

When ndmpcopy is run over SSH, it consistently stops after the configured SSH timeout period (e.g., 10 minutes), regardless of retry attempts:

• On the source-side console, Write to socket failed is reported.
• On the destination-side console, interrupted due to an abort is reported.
• In the source-side backup log  it is observed that the dump proceeds normally, then aborts with Error (Write to socket failed) or similar.
• Examining the time stamps of the Phase_change and Error lines in the backup log, the elapsed time between these two events will be a consistent interval across multiple attempts. 
  • For example, the elapsed time between the Phase_change and the error/abort is consistently 15 minutes (or some other typical timeout value).
• ndmpd log with debug level
  0000001b.0129b5ad 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG: DMA>>S V4 sequence=10 (0xa)
0000001b.0129b5ae 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG:      Time_stamp=0x691c23d4 (Nov 18 16:44:20 2025)
0000001b.0129b5af 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG:      message type=0 (NDMP4_MESSAGE_REQUEST)
0000001b.0129b5b0 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG:      message_code=0x902 (NDMP4_CONNECT_CLOSE)
0000001b.0129b5b1 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG:      reply_sequence=0 (0x0)
0000001b.0129b5b2 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG:      error_code=0 (NDMP4_NO_ERR)
0000001b.0129b5b3 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG: service_terminate called
0000001b.0129b5b4 1a6b0aef Tue Nov 18 2025 16:44:20 +09:00 [kern_ndmpd:info:6733] [10948]  DEBUG: received CLOSE command from [<node management LIF IP address>].37395