Oracle EE 11.2.0.4 on Linux x86-64.

I got a really surprising error message today when setting up a new data guard standby database.
I created a standby controlfile as usual and placed it on a common NFS share accessible also to the new data guard host:

SQL> alter database create standby controlfile as '/nfs/install/oemdb/cf2.f';

Database altered.

Now, on a new node I tried to restore that controlfile, but got a really surprising RMAN-06172: no AUTOBACKUP found or specified handle is not a valid copy or piece. This shouldn’t happen, it is just stored on a common NFS share, file should not be damaged.

RMAN> restore controlfile from '/nfs/install/oemdb/cf2.f';

Starting restore at 20-MAY-16
using channel ORA_DISK_1

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 05/20/2016 12:58:33
RMAN-06172: no AUTOBACKUP found or specified handle is not a valid copy or piece

Although the error message does not say it, but I remembered that I had mounted the NFS using SOFT mount option and when trying to restore datafiles from soft mounted NFS shared you will usually get ORA-27054: NFS file system not mounted with correct options, unless you have turned on Direct-NFS on the database kernel. So I just wondered, maybe this is the real error message in this case also.
After turning on Direct NFS, restoring the control file worked as expected:

[production|oracle@vdb0005.mlt.unibet.com oemdb]$ cd $ORACLE_HOME/rdbms/lib
[production|oracle@vdb0005.mlt.unibet.com lib]$ make -f ins_rdbms.mk dnfs_on
rm -f /u01/app/oracle/product/11.2.0.4/db/lib/libodm11.so; cp /u01/app/oracle/product/11.2.0.4/db/lib/libnfsodm11.so /u01/app/oracle/product/11.2.0.4/db/lib/libodm11.so
[production|oracle@vdb0005.mlt.unibet.com lib]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri May 20 13:01:56 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup nomount
ORACLE instance started.

Total System Global Area 9620525056 bytes
Fixed Size                  2261368 bytes
Variable Size            2449477256 bytes
Database Buffers         7147094016 bytes
Redo Buffers               21692416 bytes
SQL> Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[production|oracle@vdb0005.mlt.unibet.com lib]$ rman target /

Recovery Manager: Release 11.2.0.4.0 - Production on Fri May 20 13:02:14 2016

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: OEM (not mounted)

RMAN> restore controlfile from '/nfs/install/oemdb/cf2.f';

Starting restore at 20-MAY-16
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=474 device type=DISK

channel ORA_DISK_1: copied control file copy
output file name=+DATA/oem/controlfile/current.257.912344539
Finished restore at 20-MAY-16

The NFS share was mounted using options:
type nfs (rw,bg,soft,rsize=32768,wsize=32768,tcp,nfsvers=3,timeo=600,addr=10.10.10.10)

I’ll be presenting my brand new presentation “Using image copies for Oracle database backups” at ilOUG Tech Days on 30. May in Israel.

More information about the event can be found here

Abstract of my presentation:
When databases get ever larger and larger, backing them up using traditional RMAN backupsets will quickly get unfeasible. Completing a backup requires too much time and resources, but more importantly the same also applies to restores. RMAN has always provided a solution as incrementally updated image copies, but they are much less manageable than backupsets. This presentation goes into detail on how to successfully implement incrementally updated image copy backups, automate them and implement features that together with a capable storage system can provide almost everything that Oracle ZDLRA promises and beyond.

Looking forward to the event!