Cause

Improper NFS mount options are used. This behaviour has been observed on Solaris Linux and AIX Platforms.

Bug 5146667 ORA-27054 ERRORS WHEN RUNNING RMAN WITH NFS

Solution

Workarounds:

*.event='10298 trace name context forever, level 32'

- Use the event 10298 (It can have a side effect of disabling direct IO on RAC using regular files on NFS mounts)

Reference : Note 387700.1 ORA-27054 ERRORS WHEN RUNNING RMAN WITH NFS

OR

Apply patch for Bug 5146667

OR

- Set the mount options explictly.

Here are the mount options that need to be used for nfs volumes on Linux.

Use :
rw,bg,hard,nointr,rsize=32768,wsize=32768,tcp,vers=3,timeo=600,actimeo=0

default rsize and wsize for NFS is 4096 Blocks

so if you have rsize=32k and wsize=32k then NFS would be able to read and write large datagram as
compared to deafult one

TCP option will make sure that your client are getting the data or not

Hard & INTR - The program accessing a file on a NFS mounted file system will hang when the
server crashes. The process cannot be interrupted or killed unless you also specify intr. When
the NFS server is back online the program will continue undisturbed from where it was.

actimeo is for access timeout and it should be 0