NFS: NFSv4 callback reply buffer overflowed

We got sometimes a kernel messages with nfsv4 shares

NFSv4 callback reply buffer overflowed

[QUOTE]Apr 29 11:45:47 server01 kernel: [ 193.283103] RPC: Registered tcp NFSv4.1 backchannel transport module.
Apr 29 14:21:35 server01 kernel: [ 9525.728830] NFSv4 callback reply buffer overflowed![/QUOTE]

How big is the reply buffer?
Can we increase the buffer?

Is this a problem on client or on server side?

The nfs server is a netapp filer (ontap 8.1) which have read delegation (nfs 4.1) feature on.

kernel version:
Linux ams01 3.0.101-0.47.52-default #1 SMP Thu Mar 26 10:55:49 UTC 2015 (0e3c7c8) x86_64 x86_64 x86_64 GNU/Linux

Repository: SLES 11 SP3 Updates
Name: nfs-client
Version: 1.2.3-18.38.41.1
Arch: x86_64
Vendor: SUSE LINUX Products GmbH, Nuernberg, Germany

Hi rapideyeag,

[QUOTE=rapideyeag;27735]We got sometimes a kernel messages with nfsv4 shares

NFSv4 callback reply buffer overflowed

How big is the reply buffer?
Can we increase the buffer?

Is this a problem on client or on server side?

The nfs server is a netapp filer (ontap 8.1) which have read delegation (nfs 4.1) feature on.

kernel version:
Linux ams01 3.0.101-0.47.52-default #1 SMP Thu Mar 26 10:55:49 UTC 2015 (0e3c7c8) x86_64 x86_64 x86_64 GNU/Linux

Repository: SLES 11 SP3 Updates
Name: nfs-client
Version: 1.2.3-18.38.41.1
Arch: x86_64
Vendor: SUSE LINUX Products GmbH, Nuernberg, Germany[/QUOTE]

from what I can tell, this “buffer” is part of the RPC structure transmitted from the server to the client, and the error message results from a decode problem on behalf of the client. Hence, this is nothing you can influence on user-side. These symptoms (decoding XDR structures) can either point to a server-side problem when filling the data structures, but can as well occur when client and server side implementations differ WRT to the actual XDR message structure. So it could be an issue of (NFS) implementation version mismatches.

Anyhow, I strongly recommend to open a service request so a SUSE engineer can have a detailed look into this.

Regards
Jens