NFS mount hung after attempting operation with a large payload

Applies To

• Gen1 / Gen2 Hybrid and All Flash Series

Issue

• NFS export is mounted without any issues
• Small READ and WRITE operations succeed but large READ and WRITE operations can cause the mount to hang
• Other operations which are not small enough to fit within a standard MTU (1500 or less) can also cause a hang

Cause

Jumbo packets are not passing through the network can cause NFS hang.

Resolution

• Reduce the MTU size at both ends of the communication and remount to allow TCP to negotiate a supported size
• Or, configure Jumbo frames for all devices (storage, client, switch) to allow bigger packets in your environment.

Additional Information

• Initiate a simple ping test to reveal if bigger packets are being dropped.

ping <NGX_DATA_IP> -M do -s 1400 -c 5
ping <NGX_DATA_IP> -M do -s 4000 -c 5