环境：

ORACLE10.2.0.1

OS:REDHAT 5.3 64BIT

[@more@]

由于本地RMAN空间不足，需要将备份备到NFS服务器上，通过简单的mount -t nfs IP:/PATH /DESPATH后发现通过RMAN执行备份的时候报错：

通过oracle官方解释说：

Error: ORA-27054
Text: NFS file system where the file is created or resides is not mounted with correct options
---------------------------------------------------------------------------
Cause: The file was on an NFS partition and either reading the mount tab
file failed or the partition wass not mounted with the correct
mount option.

Action: Make sure mount tab file has read access for Oracle user and
the NFS partition where the file resides is mounted correctly.
For the list of mount options to use refer to your platform
specific documentation.


*** Important: The notes below are for experienced users - See Note:22080.1

Explanation:
As of Oracle 10.2 the IO interface layer in Oracle tries
to check that the mount options of any NFS mounted disk
used have mount options which ensure that the NFS volume
is safe to use as incorrectly mounted NFS volumes can
result in data corruption problems.

Diagnosis:
The exact checks used for an NFS mounted disk vary between
platforms but in general the basic checks will include
checking that:
- The mount table (eg; /etc/mnttab) can be read to
check the mount options
- That the NFS mount is mounted with the "hard" option
- The mount options include rsize>=32768 and wsize>=32768
- For RAC environments, where NFS disks are supported,
that the "noac" mount option is used.

Different platforms may use different or additional checks.
Note that the main checks currently check the mount options
used and not the underlying NFS attributes (as seen from
nfsstat -m on most Unix platforms) and so a disk may appear
to be mounted correctly with nfsstat (-m) but Oracle may
report ORA-27054 errors if the required options were not
explicitly stated at mount time.

If reporting an ORA-27054 error the additional information
in the error message and the platform and Oracle version
are all required to help confirm the exact reason for failing
to treat the NFS disk as correctly mounted.

Articles:

最终通过添加参数得以解决：

mount -t nfs -o rw,hard,rsize=32768,wsize=32768 10.11.15.15:/oracle/RMANBAK /u02/rman

RMAN> backup tag='20101125_bak' database format='/u02/rman/qqdb_rman/%D_%U_%S_full';

Starting backup at 25-NOV-10
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00001 name=/u01/oradata/qqdb/system01.dbf
input datafile fno=00003 name=/u01/oradata/qqdb/sysaux01.dbf
input datafile fno=00002 name=/u01/oradata/qqdb/undotbs01.dbf
input datafile fno=00004 name=/u01/oradata/qqdb/users01.dbf
input datafile fno=00005 name=/u01/oradata/qqdb/odu_test01.dbf
channel ORA_DISK_1: starting piece 1 at 25-NOV-10
channel ORA_DISK_1: finished piece 1 at 25-NOV-10
piece handle=/u02/rman/qqdb_rman/25_06lttoss_1_1_%S_full tag=20101125_BAK comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:02:15
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
including current control file in backupset
including current SPFILE in backupset
channel ORA_DISK_1: starting piece 1 at 25-NOV-10
channel ORA_DISK_1: finished piece 1 at 25-NOV-10
piece handle=/u02/rman/qqdb_rman/25_07lttp13_1_1_%S_full tag=20101125_BAK comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:05
Finished backup at 25-NOV-10