ORA-27086: unable to lock file – already in use

In Alert log :

Thu Feb 14 09:34:57 EST 2013
Errors in file /u01/app/oracle/admin/rdmetdev/udump/rdmetdev_ora_6321.trc:
ORA-27050: function called with invalid FIB/IOV structure
Additional information: 2
ORA-27086: unable to lock file – already in use
Linux-x86_64 Error: 37: No locks available
Additional information: 10

usually this problem occurred because NFS is Hanged,and can check OS logs to find “statd: server localhost not responding, timed out”.

1- Check rpc.stat is working and you can restart again , and you have to Restart NFS Services also

Stop :

# service nfslock stop
# service nfs stop
# service portmap stop
# umount /proc/fs/nfsd

 Start :

# service portmap start
# service nfs start
# service nfslock start
# mount -t nfsd nfsd /proc/fs/nfsd

Please follow the order, also note that when you restart the NFS service the server could hang at most for 1 minute.

Finally you should Reboot your server.

Thank you
Osama Mustafa