Client application experiencing high iowait for NFS traffic.
Reproducing the issue with heavy load and network tracing showed that some WRITE attempts were never being received by the NFS server, but were never sending a confirmation back to the clients.
NFS debug showed that svc_udp_recvfrom was returning 0, indicating an error, which can occur when it fails to verify the checksum while copying data from skbuffs into xdr
Red Hat Enterprise Linux 5 (NFS server)
Red Hat Enterprise Linux 5 (NFS client)
Subscriber exclusive content
A Red Hat subscription provides unlimited access to our knowledgebase of over 48,000 articles and solutions.