[CentOS] CentOS 7, NFS 4, and a non ext4 fs (like zfs)

Hello,

we want to migrate to CentOS 7(.1) , Server, Client etc ...

Right now we need to suspend that because we have some serious issues 
with NFS4 shared ZFS ( kernel module - zfs on linux project ) Volumes 
and CentOS 7 clients.

Our current server are CentOS6.5, if we share a zfs volume and do the 
following on this share: client A reads/access file "z.txt". Now client 
B replaces (copy, move, unlink+link ) files "z.txt" with a new different 
version and now client A reads/access the file "z.txt" ( and only the 
file - do not do anything which does a "stat" on the file e.g. "cat 
z.txt") the old version/content is read. As long as you do something 
that issues a "stat" for the file/dir.

This is really a problem because a soon you are not browsing through the 
dirs e.g. updating some scripts or anything automated the changes are 
not recognized by the client.

This does not happen with a ext4 share. This also happen with a 
centos7.0 NFS Server and ZFS/XFS. We permute pretty much every nfs 
mount/share option - it always happens. Nothing does help. This does not 
happen with a Centos7.1 server and a centos7.1 client and xfs (NFS4.1). 
Of course it works with our current client server Version: Ubuntu 12.04 
/ CentOS 6.5.

It really does not seem to be a zfs issue - it does look more like a nfs 
problem with certain filessystems. I asked this already on the zfs 
mailing list.

So is there something I can do?
Is the problem known?
Is there a workaround , patch or fix?

I am still unsure if I missed something completely because the problem 
is just so serious...

With kind regards

Timo Ballin




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