# NFS: NFSv4 callback reply buffer overflowed **URL:** \ **Category:** SLES Networking\ **Created:** [May 5, 2015, 2:18pm UTC](https://forums.suse.com/t/nfs-nfsv4-callback-reply-buffer-overflowed/26998 "2015-05-05T14:18:21Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![rapideyeag](https://avatars.discourse-cdn.com/v4/letter/r/2acd7d/32.png) [@rapideyeag](https://forums.suse.com/u/rapideyeag)\ **Post date:** [May 5, 2015, 2:18pm UTC](https://forums.suse.com/t/nfs-nfsv4-callback-reply-buffer-overflowed/26998/1 "2015-05-05T14:18:21Z")
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 ---
**Author:** ![Jens-U](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@Jens-U](https://forums.suse.com/u/Jens-U)\ **Post date:** [May 5, 2015, 2:46pm UTC](https://forums.suse.com/t/nfs-nfsv4-callback-reply-buffer-overflowed/26998/2 "2015-05-05T14:46:58Z")
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