http://aix4admins.blogspot.com/2011/05/server-computer-that-makes-its-file.html

https://www.ibm.com/support/pages/aix-nfs-authentication-root-user

• On the source host, check the domain:

[root@nfsserver]/root# chnfsdom
Current local domain: mydom

• On the target host, set the domain, and start NFSv4 daemon:

[root@labotest]/root# chnfsdom        
Current local domain: N/A
[root@labotest]/root# chnfsdom mydom
[root@labotest]/root# chnfsdom      
Current local domain: mydom
[root@labotest]/root# cat /etc/nfs/local_domain
mydom
[root@labotest]/root# startsrc -g nfs
0513-029 The biod Subsystem is already active.
Multiple instances are not supported.
0513-059 The nfsd Subsystem has been started. Subsystem PID is 66142.
0513-059 The rpc.mountd Subsystem has been started. Subsystem PID is 20447570.
0513-059 The nfsrgyd Subsystem has been started. Subsystem PID is 39715266.
0513-059 The gssd Subsystem has been started. Subsystem PID is 55509106.
0513-029 The rpc.lockd Subsystem is already active.
Multiple instances are not supported.
0513-029 The rpc.statd Subsystem is already active.
Multiple instances are not supported.

• On the source host, export a filestem for NFS V3 and V4 (if not specified = v3):

[root@nfsserver]/root# vi /etc/exports
/nfs_test -vers=3:4
[root@nfsserver]/root# exportfs -va

• On the target host, mount the NFSv4 exported filesystem:

[root@labotest]/root# mount -o vers=4,soft,intr nfsserver:/nfs_test /mnt 
[root@labotest]/root# mount | grep /mnt
nfsserver /nfs_test      /mnt             nfs4   Oct 28 17:19 vers=4,soft,intr

• nfsserver:2049
• clientnfs: 1022-1023

[root@labotest]/root# cat /etc/exports
/Tech/test1 -vers=4,sec=sys:krb5p:krb5i:krb5:dh,rw,access=10.1.199.35,root=10.1.199.35

# For NFS with Linux, add the following settings

nfso portcheck  1 (not sure)
nfso nfs_use_reserved_ports  1

nfs -po <param>=<value>

Example to unexport

[root@nfsserver]/root# rmnfsexp -d /export/mksysb

Example to export

[root@nfsserver]/root# mknfsexp -d /export/mksysb -v 3,4 -S sys,krb5p,krb5i,krb5,dh -r aixn*,aixa*,aixb* -t rw

Open the /etc/filesystems file on labotest with a text editor.

/mksysb:
        dev             = "/export/mksysb"
        vfs             = nfs
        nodename        = nfsserver
        mount           = true
        options         = bg,soft,intr,vers=4,sec=sys
        account         = false

[root@aix01]/var/log/syslog# grep gss warning.log
/var/adm/syslog/warning.log:Feb  1 09:21:04 aix01 daemon:err|error gssd[15663584]: /usr/lib/drivers/krb5.ext: No such file or directory
/var/adm/syslog/warning.log:Feb  1 09:21:04 aix01 daemon:err|error gssd[15663586]: /usr/lib/drivers/krb5.ext: No such file or directory

[root@aix01]/export/aix73_exp/installp/ppc# lssrc -g nfs
Subsystem         Group            PID          Status
 biod             nfs              30867940     active
 nfsd             nfs              23921040     active
 rpc.mountd       nfs              7406062      active
 nfsrgyd          nfs              19399068     active
 rpc.lockd        nfs              9175414      active
 rpc.statd        nfs              32309574     active
 gssd             nfs                           inoperative

Install the missing krb5.ext module, you can find the package modcrypt.base.6.1.0.4.I into expansion pack

[root@aix01]/export/softs# restore -Tqvf /export/aix73_exp/installp/ppc/modcrypt.base.6.1.0.4.I
New volume on /export/aix73_exp/installp/ppc/modcrypt.base.6.1.0.4.I:
...
           0 ./usr/lpp/modcrypt.base
        4334 ./usr/lpp/modcrypt.base/liblpp.a
      406327 ./usr/ccs/lib/libmodcrypt.a
      175022 ./usr/lib/drivers/krb5.ext
        5999 ./usr/include/xcrypt.h

Error while trying to export

root@ds:/root# cat /etc/exports
/export/aix72 -vers=3:4

root@ds:/root# exportfs -va
error: Too many levels of symbolic links

First chek if you have symbolic link into you directory

find /export/aix72 -type l

In symbolic link exist, remove it, else:

This problem is more common when using a NFS filesystem (v3 or v4) over an filesystems backend and with a lot of files in the same directory (more than 50000).

The problem is related to the readdir function of the readdir API, that uses the readdir cookie to quickly locate a file inside a directory. The NFS server uses this API while communicating with filesystem backends.

The “readdir loop” problem seems to be fairly widely known. Try to upgrade your OS, and reboot.

Export NFSv4

[root@aixnfssrv01]/root> cat /etc/exports
/repository -vers=3:4,sec=sys,root=aix*:lnx*:ocp*,rw

[root@aixnfssrv01]/root> chnfsdom
Current local domain: mydom1

With good domain

[root@aixclientnfs01] /root> chnfsdom mydom1
[root@aixclientnfs01] /root> stopsrc -g nfs
[root@aixclientnfs01] /root> startsrc -g nfs
[root@aixclientnfs01] /root> mount -o vers=4 aixnfssrv01:/repository /mnt
[root@aixclientnfs01] /> ls -l /   | grep mnt
   4 drwxr-xr-x   22 root     system         4096 Mar  1 16:59 mnt

With bad domain

[root@aixclientnfs01] /root> chnfsdom mydom2
[root@aixclientnfs01] /root> stopsrc -g nfs
[root@aixclientnfs01] /root> startsrc -g nfs
[root@aixclientnfs01] /root> mount -o vers=4 aixnfssrv01:/repository /mnt
[root@aixclientnfs01] /> ls -l /   | grep mnt
   4 drwxr-xr-x   22 nobody   nobody         4096 Mar  1 16:59 mnt

you can have multiple domains: chnfsdom mydom1,mydom2

If you have a dédicated VLAN for NFS, you can use MTU 9000. All devices must set the MTU to 9000 and network ports to 9216.