NFS

Necessary NFS Ports

The following ports must be opened for NFS to function properly

Port Number
111
2049

NFS Volume Refuses to Mount

ECS does support the NFS file system. However, troubles can occur when ECS is installed on the full version, or "Everything" version, of CentOS 7. Note that the following solution is not necessary on CentOS 7 Minimal.

The Problem

CentOS 7 Everything starts with NFS/RPC/Portmap components running in the root scope. This is a problem as the ECS-CE Docker container runs its own version of rpcbind. This is the instance of rpcbind that ECS is intended to communicate with. When CentOS is running rpcbind in root scope in addition to the ECS Docker container, a conflict is created and a NFS volume cannot be mounted.

This can be seen by # rpcinfo -p returning no NFS services.

The Solution

The conflict can be resolved by simply running systemctl disable rpcbind. This command will shut down the rpc service running on the host OS while leaving the Docker instance untouched.

To confirm the CentOS service is gone, run rpcinfo -p in the CentOS shell. This should return an error: rpcinfo: can't contact portmapper: RPC: Remote system error - No such file or directory

The same command, rpcinfo-p, can be run in the Docker container, which should return something similar to:

   program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100005    3   tcp   2049  mountd
    100005    3   udp   2049  mountd
    100003    3   tcp   2049  nfs
    100024    1   tcp   2049  status
    100021    4   tcp  10000  nlockmgr
    100021    4   udp  10000  nlockmgr

NFS should now function correctly.