今日无聊，做了下关于DG的有关standby_file_management参数设置的一些实验。

其中一个实验，是在primary数据库将test表空间的数据库文件/dev/raw/raw5数据文件改名至/oracle/oradata/jnjg/test01.dbf

步骤如下：

sql>atler tablespace test offline;

sql>host

dd if=/dev/raw/raw5 f=/oracle/oradata/jnjg/test01.dbf

sql>alter database rename file '/dev/raw/raw5' to '/oracle/oradata/jnjg/test01.dbf';

sql>alter tablespace test online;

出现以下错误：

ERROR at line 1:
ORA-01157: cannot identify/lock data file 5 - see DBWR trace file
ORA-01110: data file 5: '/oracle/oradata/mytmp01.dbf'

告警日志中出现：

alter tablespace mytmp online
Sun Dec 20 08:04:47 2009
Errors in file /oracle/admin/jnjg/bdump/jnjg_dbw0_8308.trc:
ORA-01157: cannot identify/lock data file 5 - see DBWR trace file
ORA-01110: data file 5: '/oracle/oradata/mytmp01.dbf'
ORA-27046: file size is not a multiple of logical block size
Additional information: 1
ORA-1157 signalled during: alter tablespace mytmp online...

在命令行下，通过oerr命令查看错误号内容：

oerr ora 27046

bash-3.1$ oerr ora 27046
27046, 00000, "file size is not a multiple of logical block size"
// *Cause:  file size as indicated by stat is not correct, additional
//          information indicates which function encountered the error
// *Action: verify that the file has not been overwritten or truncated

没看出来有什么能够解决的方法，后来想了想,dd的时候没有制定bs参数，是不是因为操作系统块跟block_size不一致所致，于是

rm /oracle/oradata/jnjg/test01.dbf

dd if=/dev/raw/raw5 f=/oracle/oradata/jnjg/test01.dbf bs=8192

sql>alter tablespace test online;

成功