Phenomenon:

A NAS storage is shared as an NFS file to a Linux host. After one day of service feedback, df -h is stuck and cannot be displayed back and forth. umount cannot be displayed. However, after restarting, df -h is back to normal. You need to check whether it is a NAS storage problem.

Solution:

1. strace tracking logs are as follows:

I found that the place where the NAS is mounted is stuck and can't continue.

2, check whether the Hard parameter is used. The Hard parameter can access the share without restriction. If the network is disconnected, it will cause a jam.

nfsstat -m

found, but the network is connected, telenet each port.

2, view the operating system version and kernel, especially the kernel

OS :Red hat 7.6

kernel: 3.10.0-957.e17

2, through troubleshooting by various parties, we searched the Linux official website and found that there is such a saying

https://access.redhat.com/solutions/3742871

that is to say, 3.10.0-957. There is a bug in Red Hat,Centos, etc. of the e17 Kernel. In This kernel case, when encountering network jitter or other problems, df -h may be stuck. You need to upgrade the kernel to solve this problem.

Solution:

upgrade the Linux kernel.

-Work-