NFS question

[Doug Henry]

I have an NFS issue that I wanted to see if anyone has seen before.  My basic setup is a linux server, and mixed client machines.  On the linux server there is a large raid which is a giant playground of data and has the following share defined:

/raid/data    *(sync,rw,all_squash,anonuid=10000,anongid=10000)

I do this because ownership and permissions are meaningless on this data share, and it keeps all data files usable by all...all of the time. 
It works perfectly under linux, solaris, and through samba to my windows clients.  On my IRIX machine (stay with me...it may not be an irix issue) I can create and delete files properly, but if I do a chmod, I get an operation denied message.  Strangely, irix seems to check if I am the owner of the file before performing the chmod and fails, but all other basic file operations work as expected.

Any and all suggestions welcome.

-thanks