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Oracle Linux : NFS Mount Point on ZFS storage Takes 49s Wait On Fcntl64 (Doc ID 2501807.1)

Last updated on MAY 24, 2020

Applies to:

Linux OS - Version Oracle Linux 6.0 and later
Information in this document applies to any platform.


NFS requests from Oracle Linux to a ZFS storage appliance was showing an unexpected delay of 50 seconds to complete. The NFS was mounted as version3 over TCP on Linux.

The strace output showed the following delay:

121647 13:41:04 fstat64(5, {st_mode=S_IFREG|0664, st_size=212992, ...}) = 0 <0.000018>
121647 13:41:04 fcntl64(5, F_SETLK, {type=F_RDLCK, whence=SEEK_SET, start=0, len=0}) = 0 <49.996835> >> 50 seconds

The fcntl64 function being called is trying to release an NFS read lock from the NFS server.

However, we can verify that the NFS Lock Manager (NLM) runs fine on the NFS server:

# rpcinfo -p <NFS-server> |grep nlockmgr
100021 1 udp 4045 nlockmgr
100021 2 udp 4045 nlockmgr
100021 3 udp 4045 nlockmgr
100021 4 udp 4045 nlockmgr
100021 1 tcp 4045 nlockmgr >> TCP on v1
100021 2 tcp 4045 nlockmgr >> TCP on v2
100021 3 tcp 4045 nlockmgr >> TCP on v3
100021 4 tcp 4045 nlockmgr >> TCP on v4


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