NFS3 mount fails with error "Unable to connect to NFS server: VSI node (5001:)"
Article ID: 405771
Updated On:
Products
VMware vSphere ESXi
Issue/Introduction
1. Unable to mount NFS3 datastores from vCenter GUI.
2. Below errors are seen in VC UI and SSH session -
An error occurred during host configuration: . Operation failed, diagnostics report: Mount failed: Unable to complete Sysinfo operation. Please see the VMkernel log file for more details.: Unable to connect to NFS server: VSI node (5001:)
vmkernel: cpu115:2102037 opID=64547d2a)NFS: 3500: NFS mount failed for ABC.COM:/12345_volume. Status: Unable to connect to NFS Server
Environment
ESXi 7.x
ESXi 8.x
NFS3
Cause
Port 635 between the ESXi host and the NFS server is blocked. This was confirmed using a live packet capture, which showed missing acknowledgments during the handshake process.
For more details on using the pktcap-uw tool, refer to KB Packet capture on ESXi using the pktcap-uw tool
pktcap-uw --uplink vmnic2 --dir 2 --ip 147.###.###.94 -o - | tcpdump-uw -enr -
16:18:10.671175 00:##:##:##:##:77 > 7c:##:##:##:##:e2, ethertype IPv4 (0x0800), length 66: 147.###.###.94.111 > 10.###.##.123.966: Flags [.], ack 97, win 258, options [nop,nop,TS val 3456265750 ecr 2560786495], length 0
16:18:10.671198 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 60: 10.###.##.123.966 > 147.###.###.94.111: Flags [R], seq 2005412428, win 0, length 0
16:18:11.640473 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [SEW], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266801783 ecr 0], length 0
16:18:12.850436 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266801904 ecr 0], length 0
16:18:14.060431 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266802025 ecr 0], length 0
16:18:15.270398 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266802146 ecr 0], length 0
16:18:16.480383 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266802267 ecr 0], length 0
16:18:18.690529 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266802488 ecr 0], length 0
16:18:22.910464 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.967 > 147.###.###.94.635: Flags [S], seq 2273045365, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1266802909 ecr 0], length 0
16:18:25.634288 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [SEW], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717060780 ecr 0], length 0
16:18:26.650215 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [SEW], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717060881 ecr 0], length 0
16:18:27.860372 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717061003 ecr 0], length 0
16:18:29.070191 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717061124 ecr 0], length 0
16:18:30.280174 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717061245 ecr 0], length 0
16:18:31.490149 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717061366 ecr 0], length 0
16:18:33.700120 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717061587 ecr 0], length 0
16:18:37.910223 7c:##:##:##:##:e2 > 00:##:##:##:##:68, ethertype IPv4 (0x0800), length 74: 10.###.##.123.968 > 147.###.###.94.635: Flags [S], seq 2955694893, win 65535, options [mss 1460,nop,wscale 9,sackOK,TS val 1717062008 ecr 0], length 0
Resolution
Engage internal security (firewall) team to unblock port 635 to resolve the issue.
Additional Information
For more details on ports required by ESXi hosts, refer to VMware Ports and Protocols vSphere
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