Block change tracking进程记录自从上一次0级备份以来数据块的变化,并把这些信息记录在跟踪文件中。
RMAN使用这个文件判断增量备份中需要备份的变更数据;极大的提高了备份性能和速度,RMAN可以不再扫描整个文件以查找变更数据。
查看快跟踪是否开启
sql> col FILENAME for a20
sql> select * from v$block_change_tracking;
STATUS FILENAME BYTES
---------- -------------------- ----------
disABLED
sql>
sql> select name from v$asm_diskgroup;
NAME
------------------------------
DATA
OCR
sql>
开启块跟踪功能
sql> alter database enable block change tracking using file '+DATA';
Database altered.
sql> select status,filename,bytes/1024/1024 M from v$block_change_tracking;
STATUS FILENAME M
---------- -------------------- ----------
ENABLED +DATA/test11g/change 11.0625
tracking/ctf.350.984
678355
sql>
sql> alter database disable block change tracking;
Database altered.
sql>
sql> select status,filename,bytes/1024/1024 M from v$block_change_tracking;
STATUS FILENAME M
---------- -------------------- ----------
disABLED
sql>