oracle rac 11.2 环境下备份控制文件报ORA-00245错误的解决

郑全

环境是 rac +rac的DG环境（版本是11.2.0.4），standby rac 环境在重启之后控制文件备份在一个节点失败，另一个节点备份可以成功
rac数据库重启之后备份控制文件报ORA-00245: control file backup failed; target is likely on a local file system感觉很奇怪，数据库在没有重启之前备份是好的
通过查询资料说是快照控制文件设置到本地原因，我的快照文件确实是设置到本地了
RMAN> show all;
using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name ORCLDG are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO SHIPPED TO ALL STANDBY;
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/oracle/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_orcl1.f';
现在备份控制文件时无法创建快照，但在rac另一个节点是可以的，有点奇怪
把控制文件设置到asm磁盘组中控制文件可以备份
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+systemdg/snapshotcontrof/snapcf_orcl1.f';
snapshot control file作用只有在同步catalog的时候用到或者在控制文件备份的时候用到，主要作用是在备份控制文件时代替控制文件，使得rman在备份控制文件时能够锁定控制文件从而保证控制文件的一致性。

如下mos上解释11gR2, any instance in the cluster may write to the snapshot controlfile，所以每个节点都要能访问到，但是解释不同另一节点可以设置snapshot
controlfile到本地，能备份控制文件成功，为了保险还是设置snapshot controlfile 到asm共享磁盘



ORA-245: In RAC environment from 11.2 onwards Backup Or Snapshot controlfile needs to be in shared location (文档 ID 1472171.1) 转到底部   






In this Document

Description
  Occurrence
  Symptoms
  Workaround
  Patches
  History
  References

APPLIES TO:
Oracle Database - Enterprise Edition - Version 11.2.0.1.0 and later
Information in this document applies to any platform.
This issue is only applicable to RAC database.
From 11gR2 onwards, the controlfile backup happens without holding the controlfile enqueue. For non-RAC database, this doesn't change anything. But for RAC database, due to the changes made to the controlfile backup mechanism in 11gR2, any instance in the cluster may write to the snapshot controlfile. Due to this snapshot controlfile need to be visible to all instances.
The snapshot controlfile MUST be accessible by all nodes of a RAC database, if the snapshot controlfile does not reside on a shared device error will be raised at the time of RMAN backup while taking snapshot of controlfile.
This applies to backing up controlfile using sqlplus / having autobackup of controlfile configured on non
shared location.
ORA-245 error message description
----------------------------------------
00245, 00000, "control file backup operation failed"
*Cause: Failed to create a control file backup because some process
signaled an error during backup creation.
*Action: Check alert files for further information. This usually happens
because some process could not access the backup file during
backup creation. Any process of any instance that starts a
read/write control file transaction must have an access to the
backup control file during backup creation.
DESCRIPTION

1. In RAC environment controlfile autobackup fails with ora-0245
Autobackup of controlfile in RMAN is failing with error:
RMAN-571: ===========================================================
RMAN-569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-571: ===========================================================
RMAN-3009: failure of Control File and SPFILE Autobackup command on
ORA_DISK_1 channel at 10/27/2010 12:13:31
ORA-245: control file backup operation failed

2. In RAC environment, backup controlfile to non shared location fails
SQL> ALTER DATABASE BACKUP CONTROLFILE TO '/home/rac1122/test/control.bk' REUSE
*
ERROR at line 1:
ORA-245: control file backup operation failed

3. In RAC environment backing up standby controlfile to non shared location fails
SQL> alter database create standby controlfile as '/home/oracle/renostdbycntrl.ctl';
alter database create standby controlfile as
'/home/oracle/renostdbycntrl.ctl'
*
ERROR at line 1:
ORA-245: control file backup operation failed

4. In RAC environment copy current controlfile to '${DB_BACKUP_DIR}/rac_tnctv_control.bak';
channel ch1: starting datafile copy
copying current control file
RMAN-571: ===========================================================
RMAN-569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-571: ===========================================================
RMAN-3009: failure of backup command on 10/07/2011 11:36:42 channel at ch1
ORA-245: control file backup operation failed

5. In RAC environment, Rman backup fails if snapshot controlfile is not in shared location.
RMAN-00571: ========================================================
RMAN-00569: ============ ERROR MESSAGE STACK FOLLOWS =============
RMAN-00571: =========================================================
RMAN-03009: failure of resync command on default channel at 03/13/2012 10:19:41
ORA-00245: control file backup operation failed
OCCURRENCE
Only affect Real application Cluster (RAC ), 11.2 specific.
SYMPTOMS
In RAC environment any form of controlfile backup may fail with ORA-0245 if the location of the Snapshot Controlfile is not a shared location.
The backup of the controlfile actualy makes a backup of the SNAPSHOT controlfile. The Snapshot controlfile is created when the controlfile is about to be backed up.
The Snapshot controlfile is a read-consistent copy of the controlfile.

WORKAROUND
SOLUTION:

This is a RAC specific 'configuration' issue and the correct configuration is as described below
It is changed behaviour which requires that the snapshot controlfile in a RAC environment, is on a shared location.
1. Check the snapshot controlfile location:


RMAN> show snapshot controlfile name;
2. Configure the snapshot controlfile to a shared disk:
RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '<shared_disk>/snapcf_<DBNAME>.f';
Or in case of ASM use
RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+<DiskGroup>/snapcf_<DBNAME>.f'