從RMAN備份集中還原Archive log
1、Rman的restore與recover是不同的概念：
restore：指從已產生的備份集中，找出一個或多個物件（檔案），還原檔案到指定的位置。
recover：通常透過重做交易（從redo log及archive log）來恢復資料庫的資料。
2、找出要restore 的 archive log
RMAN> list backup of archivelog all;
List of Backup Sets
===================
BS Key Size Device Type Elapsed Time Completion Time
------- ---------- ----------- ------------ ---------------
1662 58G SBT_TAPE 00:45:28 12-DEC-12
BP Key: 1658 Status: AVAILABLE Tag: TAG20121212T223215
Piece Name: 7420_DB_Backup_incr_0
List of Archived Logs in backup set 1662
Thrd Seq Low SCN Low Time Next SCN Next Time
---- ------- ---------- --------- ---------- ---------
1 4816 14339859122 12-DEC-12 14340109617 12-DEC-12
1 4817 14340109617 12-DEC-12 14340408790 12-DEC-12
1 4818 14340408790 12-DEC-12 14340520580 12-DEC-12
1 4819 14340520580 12-DEC-12 14340681895 12-DEC-12
1 4820 14340681895 12-DEC-12 14340901575 12-DEC-12
3、假設要 restore 的是 seq=4816，腳本可以是：
run {allocate channel 'ci' type 'sbt_tape';
restore archivelog from sequence 4816 until sequence 4816;
release channel 'ci';}
假設要 restore 的是 seq=4816、4817、4818，腳本可以是：
run {allocate channel 'ci' type 'sbt_tape';
restore archivelog from sequence 4816 until sequence 4818;
release channel 'ci';}
因為我的備份集是在磁帶上，所以指定channel的type為'sbt_tape'
RMAN> run {allocate channel 'ci' type 'sbt_tape';
restore archivelog from sequence 4823 until sequence 4823;
release channel 'ci';}
allocated channel: ci
channel ci: sid=245 devtype=SBT_TAPE
channel ci: Data Protector A.05.50/330
Starting restore at 13-DEC-12
channel ci: starting archive log restore to default destination
channel ci: restoring archive log
archive log thread=1 sequence=4823
[Normal] From: OB2BAR_Oracle8@hp7420 "PROD" Time: 12/13/12 10:32:32
Starting OB2BAR Restore: hp7420:7420_DB_Backup_incr_0
[Normal] From: OB2BAR_Oracle8@hp7420 "PROD" Time: 12/13/12 10:56:23
Completed OB2BAR Restore: hp7420:7420_DB_Backup_incr_0
channel ci: restored backup piece 1
piece handle=7420_DB_Backup_incr_0
channel ci: restore complete
Finished restore at 13-DEC-12
released channel: ci
4、在還原archive log的過程中，可以查看磁帶機的狀態（HP-UX）：
hp7420: mc -p /dev/rac/c2t0d0 -r DS
DT_slot_1 FULL
ST_slot_1 FULL
ST_slot_2 FULL
ST_slot_3 EMPTY
ST_slot_4 FULL
ST_slot_5 FULL
ST_slot_6 FULL
ST_slot_7 FULL
ST_slot_8 FULL
因為要還原的備份集在第三捲磁帶內，所以磁帶就從ST_slot_3移到DT_slot_1
