在oracle下我们如何正确的执行数据库恢复
當(dāng)數(shù)據(jù)庫需要進(jìn)行介質(zhì)恢復(fù)時，為了確保數(shù)據(jù)庫能夠順利的執(zhí)行恢復(fù)過程，恢復(fù)數(shù)據(jù)庫到當(dāng)前狀態(tài)。我們要做的就是驗(yàn)證！驗(yàn)證什么呢？當(dāng)然是驗(yàn)證備份集和歸檔是否能夠進(jìn)行有效的恢復(fù)。防止我們restore后，執(zhí)行recover時卻發(fā)現(xiàn)歸檔缺少了一堆，頓時傻眼。
比方說，在數(shù)據(jù)庫當(dāng)前日志序列號為3時我們完全備份了數(shù)據(jù)庫。在數(shù)據(jù)庫當(dāng)前聯(lián)機(jī)日志序列號為13時數(shù)據(jù)庫損壞需要恢復(fù)。假設(shè)數(shù)據(jù)庫聯(lián)機(jī)日志組為3組，則可以推斷數(shù)據(jù)庫聯(lián)機(jī)日志序列號分別為11、12、13。因此當(dāng)數(shù)據(jù)庫執(zhí)行restore database后，再執(zhí)行recover時不難推斷數(shù)據(jù)庫需要應(yīng)用歸檔3、4、5、6、7、8、9、10以及聯(lián)機(jī)日志11、12、13來進(jìn)行完全恢復(fù)。
為了能夠順利的執(zhí)行完全恢復(fù)，我們在執(zhí)行恢復(fù)前，需要對restore調(diào)用的備份集進(jìn)行恢復(fù)驗(yàn)證（語句為：restorevalidate database）以及驗(yàn)證recover過程所需的歸檔3-10（語句為：restore validate archivelog sequence between 3 and10）。
以完全恢復(fù)為例，舉例如下：
1數(shù)據(jù)庫當(dāng)前日志seq號為59，我們備份數(shù)據(jù)庫
SQL> selectgroup#,archived,sequence#,status from v$log;
? GROUP# ARC ?SEQUENCE# STATUS
---------- --- ---------- ----------------
? ? ? ?1 YES ? ? ? ? 58 INACTIVE
? ? ? ?2 NO ? ? ? ? 59 CURRENT
? ? ? ?3 YES ? ? ? ? 57 INACTIVE
RMAN> backup database format'/backup/fullbk-%T-%U.bak'; ? ? ?
Starting backup at 2014-02-17 12:03:28
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafilebackup set
channel ORA_DISK_1: specifying datafile(s)in backup set
input datafile file number=00004name=/oracle/CRM/CRM/users01.dbf
input datafile file number=00001name=/oracle/CRM/CRM/system01.dbf
input datafile file number=00002name=/oracle/CRM/CRM/sysaux01.dbf
input datafile file number=00003name=/oracle/CRM/CRM/undotbs01.dbf
input datafile file number=00005name=/oracle/CRM/CRM/crm.dbf
input datafile file number=00006name=/oracle/CRM/test.dbf
input datafile file number=00008name=/oracle/CRM/jxc.dbf
input datafile file number=00007name=/oracle/CRM/user01.dbf
channel ORA_DISK_1: starting piece 1 at2014-02-17 12:03:29
channel ORA_DISK_1: finished piece 1 at2014-02-17 12:05:57
piecehandle=/backup/fullbk-20140217-3ep0rj0h_1_1.bak tag=TAG20140217T120328 comment=NONE
channel ORA_DISK_1: backup set complete,elapsed time: 00:02:28
channel ORA_DISK_1: starting full datafilebackup set
channel ORA_DISK_1: specifying datafile(s)in backup set
including current control file in backupset
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at2014-02-17 12:06:01
channel ORA_DISK_1: finished piece 1 at2014-02-17 12:06:02
piecehandle=/backup/fullbk-20140217-3fp0rj56_1_1.bak tag=TAG20140217T120328comment=NONE
channel ORA_DISK_1: backup set complete,elapsed time: 00:00:01
Finished backup at 2014-02-17 12:06:02
2 當(dāng)數(shù)據(jù)庫聯(lián)機(jī)日志為69時數(shù)據(jù)庫崩潰需要進(jìn)行介質(zhì)恢復(fù)
SQL> selectgroup#,archived,sequence#,status from v$Log;
? GROUP# ARC ?SEQUENCE# STATUS
---------- --- ---------- ----------------
? ? ? ?1 YES ? ? ? ? 67 INACTIVE
? ? ? ?2 YES ? ? ? ? 68 INACTIVE
? ? ? ?3 NO ? ? ? ? ?69 CURRENT
注意：這里其實(shí)我們可以推斷，如果數(shù)據(jù)庫需要恢復(fù)到當(dāng)前狀態(tài)，那么歸檔59到歸檔66的所有歸檔，必須能夠進(jìn)行有效的恢復(fù)。我們只需要發(fā)起restore database preview命令，Oracle便可以給出我們歸檔列表，繼續(xù)往下看。
3 判定當(dāng)前數(shù)據(jù)庫恢復(fù)所需要備份集和歸檔條目
注意對于restore database preview列出的歸檔條目，recover執(zhí)行完全恢復(fù)時并不會完全應(yīng)用，因?yàn)橥耆謴?fù)recover過程是：應(yīng)用相關(guān)歸檔+ 所有聯(lián)機(jī)日志，seq號從小到大依次應(yīng)用。后面會抓取recover過程，這里先暫且提一下。
RMAN> restore database preview;
Starting restore at 2014-02-17 16:14:21
using target database control file insteadof recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=63 device type=DISK
List of Backup Sets
===================
BS Key Type LV Size ? ? ? Device TypeElapsed Time Completion Time ? ?
------- ---- -- ---------- ----------------------- -------------------
108 ? ?Full ? ?2.03G ? ? ?DISK ? ? ? ?00:02:26 ? ? 2014-02-17 12:05:38
? ? ? BP Key: 108 ? Status:AVAILABLE ?Compressed: NO ?Tag: TAG20140217T120328
Piece Name:/backup/fullbk-20140217-3ep0rj0h_1_1.bak ?
注意：這里顯示備份片總是rman資料庫中記錄的數(shù)據(jù)文件最新的備份
List of Datafiles in backup set 108
File LV Type Ckp SCN ? ?CkpTime ? ? ? ? ? ?Name
---- -- ---- ---------- ------------------- ----
1 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29/oracle/CRM/CRM/system01.dbf
2 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29/oracle/CRM/CRM/sysaux01.dbf
3 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29/oracle/CRM/CRM/undotbs01.dbf
4 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29/oracle/CRM/CRM/users01.dbf
5 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29 /oracle/CRM/CRM/crm.dbf
6 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29 /oracle/CRM/test.dbf
7 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29 /oracle/CRM/user01.dbf
8 ? ? ? Full 4028039 ? ?2014-02-17 12:03:29 /oracle/CRM/jxc.dbf
using channel ORA_DISK_1
List of Archived Log Copies for databasewith db_unique_name CRM
=====================================================================
Key ? ?Thrd Seq ? ?S Low Time ? ? ? ? ?
------- ---- ------- - -------------------
131 ? ?1 ? ?59 ? ? ?A 2014-02-17 11:55:37
Name:/oracle/archivelog/arch_1_59_839098938.arch
132 ? ?1 ? ?60 ? ? ?A 2014-02-17 12:10:20
Name:/oracle/archivelog/arch_1_60_839098938.arch
133 ? ?1 ? ?61 ? ? ?A 2014-02-17 12:10:21
Name:/oracle/archivelog/arch_1_61_839098938.arch
134 ? ?1 ? ?62 ? ? ?A 2014-02-17 12:10:26
Name:/oracle/archivelog/arch_1_62_839098938.arch
135 ? ?1 ? ?63 ? ? ?A 2014-02-17 12:10:30
Name:/oracle/archivelog/arch_1_63_839098938.arch
136 ? ?1 ? ?64 ? ? ?A 2014-02-17 12:10:31
Name:/oracle/archivelog/arch_1_64_839098938.arch
137 ? ?1 ? ?65 ? ? ?A 2014-02-17 12:10:32
Name:/oracle/archivelog/arch_1_65_839098938.arch
138 ? ?1 ? ?66 ? ? ?A 2014-02-17 12:10:33
Name:/oracle/archivelog/arch_1_66_839098938.arch
139 ? ?1 ? ?67 ? ? ?A 2014-02-17 12:10:34
?Name:/oracle/archivelog/arch_1_67_839098938.arch
140 ? ?1 ? ?68 ? ? ?A 2014-02-17 12:10:36
Name:/oracle/archivelog/arch_1_68_839098938.arch
Media recovery start SCN is 4028039
Recovery must be done beyond SCN 4028039 toclear datafile fuzziness
Finished restore at 2014-02-17 16:14:24
注意：
1 上面seq號這一列顯示的最后一個歸檔seq為68（從前面可知數(shù)據(jù)庫當(dāng)前聯(lián)機(jī)日志文件seq號為69）也就是說restore database preview顯示的歸檔列表結(jié)果中最后一個歸檔seq號總是比當(dāng)前聯(lián)機(jī)日志（當(dāng)前聯(lián)機(jī)日志也就是查看v$log狀態(tài)為currnt的日志組）文件seq號小于1.
2 ?結(jié)合當(dāng)前數(shù)據(jù)庫的聯(lián)機(jī)日志組seq號分別為67 68 69，可以判斷：在recover應(yīng)用最后一個歸檔seq號為66后，oracle會讀取seq號為67、68、69聯(lián)機(jī)日志文件繼續(xù)推進(jìn)該數(shù)據(jù)庫來實(shí)現(xiàn)整個數(shù)據(jù)庫完全恢復(fù)過程。
下面將演示整個驗(yàn)證和恢復(fù)過程:
4 驗(yàn)證恢復(fù)時需要用到的備份集是否能夠正常恢復(fù)。
RMAN> restore validate database;
注意：這條命令直接會去rman資料庫中找最新的備份集進(jìn)行驗(yàn)證，也就是restore database preview命令顯示的備份集。
Starting restore at 2014-02-17 16:14:59
using channel ORA_DISK_1
channel ORA_DISK_1: starting validation ofdatafile backup set
channel ORA_DISK_1: reading from backuppiece /backup/fullbk-20140217-3ep0rj0h_1_1.bak
channel ORA_DISK_1: piecehandle=/backup/fullbk-20140217-3ep0rj0h_1_1.bak tag=TAG20140217T120328
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: validation complete,elapsed time: 00:00:36
Finished restore at 2014-02-17 16:15:35
5 驗(yàn)證恢復(fù)時應(yīng)用的歸檔
RMAN> restore validate archivelogsequence between 59 and 66;
Starting restore at 2014-02-17 16:16:34
using channel ORA_DISK_1
channel ORA_DISK_1: scanning archived log /oracle/archivelog/arch_1_59_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_60_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_61_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_62_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_63_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_64_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_65_839098938.arch
channel ORA_DISK_1: scanning archived log/oracle/archivelog/arch_1_66_839098938.arch
Finished restore at 2014-02-17 16:16:37
6 執(zhí)行restore和recover過程如下
RMAN> restore database;
Starting restore at 2014-02-17 16:36:23
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=63 device type=DISK
channel ORA_DISK_1: starting datafilebackup set restore
channel ORA_DISK_1: specifying datafile(s)to restore from backup set
channel ORA_DISK_1: restoring datafile 00001to /oracle/CRM/CRM/system01.dbf
channel ORA_DISK_1: restoring datafile00002 to /oracle/CRM/CRM/sysaux01.dbf
channel ORA_DISK_1: restoring datafile00003 to /oracle/CRM/CRM/undotbs01.dbf
channel ORA_DISK_1: restoring datafile00004 to /oracle/CRM/CRM/users01.dbf
channel ORA_DISK_1: restoring datafile00005 to /oracle/CRM/CRM/crm.dbf
channel ORA_DISK_1: restoring datafile00006 to /oracle/CRM/test.dbf
channel ORA_DISK_1: restoring datafile00007 to /oracle/CRM/user01.dbf
channel ORA_DISK_1: restoring datafile00008 to /oracle/CRM/jxc.dbf
channel ORA_DISK_1: reading from backuppiece /backup/fullbk-20140217-3ep0rj0h_1_1.bak
channel ORA_DISK_1: piecehandle=/backup/fullbk-20140217-3ep0rj0h_1_1.bak tag=TAG20140217T120328
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete,elapsed time: 00:02:08
Finished restore at 2014-02-17 16:38:35
注意：restore后我們通過查詢x$kcvfh的redo字節(jié)地址(RBA)的seq號(也就是是FHRBA_SEQ字段)可以得到restore database 后數(shù)據(jù)文件頭部記錄的rba.seq號, 該值近一步表明recover過程需要從seq號為59歸檔開始應(yīng)用。
或者也可以從restore database后數(shù)據(jù)文件頭部的scn值，對比歸檔的first_change# 和 next_change# 推斷出recover 需要應(yīng)用歸檔開始。
SQL> select hxfil,fhscn,fhrba_seq fromx$kcvfh;
? ?HXFIL FHSCN ? ? ? ? ? ? FHRBA_SEQ
---------- ---------------- ----------
? ? ? ?1 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?2 4028039 ? ? ? ? ? ? ? ? 59
? ? ? ?3 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?4 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?5 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?6 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?7 4028039 ? ? ? ? ? ? ? ? ?59
? ? ? ?8 4028039 ? ? ? ? ? ? ? ? ?59
8 rows selected.
當(dāng)然restore database 后，我們也可以直接查詢v$recvoery_log來得到recover過程需要應(yīng)用的歸檔條目，如下所示：
select * from v$recovery_log;
?THREAD# ?SEQUENCE# TIME ? ? ?ARCHIVE_NAME
---------- ---------- --------- ------------------------------------------------------------
? ? ? ?1 ? ? ? ? 59 17-FEB-14/oracle/archivelog/arch_1_59_839098938.arch
? ? ? ?1 ? ? ? ? 60 17-FEB-14/oracle/archivelog/arch_1_60_839098938.arch
? ? ? ?1 ? ? ? ? 61 17-FEB-14 /oracle/archivelog/arch_1_61_839098938.arch
? ? ? ?1 ? ? ? ? 62 17-FEB-14/oracle/archivelog/arch_1_62_839098938.arch
? ? ? ?1 ? ? ? ? 63 17-FEB-14/oracle/archivelog/arch_1_63_839098938.arch
? ? ? ?1 ? ? ? ? 64 17-FEB-14/oracle/archivelog/arch_1_64_839098938.arch
? ? ? ?1 ? ? ? ? 65 17-FEB-14/oracle/archivelog/arch_1_65_839098938.arch
? ? ? ?1 ? ? ? ? 66 17-FEB-14/oracle/archivelog/arch_1_66_839098938.arch
RMAN> recover database;
Starting recover at 2014-02-17 16:45:01
using channel ORA_DISK_1
starting media recovery
archived log for thread 1 with sequence 59is already on disk as file /oracle/archivelog/arch_1_59_839098938.arch
archived log for thread 1 with sequence 60is already on disk as file /oracle/archivelog/arch_1_60_839098938.arch
archived log for thread 1 with sequence 61is already on disk as file /oracle/archivelog/arch_1_61_839098938.arch
archived log for thread 1 with sequence 62is already on disk as file /oracle/archivelog/arch_1_62_839098938.arch
archived log for thread 1 with sequence 63is already on disk as file /oracle/archivelog/arch_1_63_839098938.arch
archived log for thread 1 with sequence 64is already on disk as file /oracle/archivelog/arch_1_64_839098938.arch
archived log for thread 1 with sequence 65is already on disk as file /oracle/archivelog/arch_1_65_839098938.arch
archived log for thread 1 with sequence 66is already on disk as file /oracle/archivelog/arch_1_66_839098938.arch
archived log for thread 1 with sequence 67is already on disk as file /oracle/archivelog/arch_1_67_839098938.arch
archived log for thread 1 with sequence 68is already on disk as file /oracle/archivelog/arch_1_68_839098938.arch
archived log filename=/oracle/archivelog/arch_1_59_839098938.arch thread=1 sequence=59
archived log file name=/oracle/archivelog/arch_1_60_839098938.archthread=1 sequence=60
archived log filename=/oracle/archivelog/arch_1_61_839098938.arch thread=1 sequence=61
archived log filename=/oracle/archivelog/arch_1_62_839098938.arch thread=1 sequence=62
archived log filename=/oracle/archivelog/arch_1_63_839098938.arch thread=1 sequence=63
archived log filename=/oracle/archivelog/arch_1_64_839098938.arch thread=1 sequence=64
archived log filename=/oracle/archivelog/arch_1_65_839098938.arch thread=1 sequence=65
archived log filename=/oracle/archivelog/arch_1_66_839098938.arch thread=1 sequence=66
media recovery complete, elapsed time:00:00:08
Finished recover at 2014-02-17 16:45:16
注意：這里可以清楚的看到應(yīng)用的歸檔條目（紅色標(biāo)記處）
7 跟蹤recover過程內(nèi)容如下：
alter database recoverlogfile '/oracle/archivelog/arch_1_59_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_59_839098938.arch
Mon Feb 17 16:45:12 2014
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_59_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_60_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_60_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_60_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_61_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_61_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_61_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_62_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_62_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_62_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_63_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_63_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_63_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_64_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_64_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_64_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_65_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_65_839098938.arch
ORA-279 signalled during: alter databaserecover logfile '/oracle/archivelog/arch_1_65_839098938.arch'...
alter database recoverlogfile '/oracle/archivelog/arch_1_66_839098938.arch'
Media Recovery Log/oracle/archivelog/arch_1_66_839098938.arch
Mon Feb 17 16:45:14 2014
Recovery of Online RedoLog: Thread 1 Group 1 Seq 67 Reading mem 0
Mem# 0: /oracle/CRM/CRM/redo01.log
Recovery of Online RedoLog: Thread 1 Group 2 Seq 68 Reading mem 0
Mem# 0: /oracle/CRM/CRM/redo02.log
Recovery of Online RedoLog: Thread 1 Group 3 Seq 69 Reading mem 0
Mem# 0: /oracle/CRM/CRM/redo03.log
Media Recovery Complete(CRM)
注意：通過跟蹤整個恢復(fù)過程，可以清楚的觀察到在用recover進(jìn)行完全恢復(fù)時，先應(yīng)用歸檔，后再通過所有聯(lián)機(jī)日志文件推進(jìn)整個數(shù)據(jù)庫來實(shí)現(xiàn)完全恢復(fù)的過程。
8 如果數(shù)據(jù)庫進(jìn)行不完全恢復(fù)如何獲取恢復(fù)所需要的歸檔
以基于時間點(diǎn)恢復(fù)為例，我們可以這么使用得出恢復(fù)到這個時間點(diǎn)數(shù)據(jù)庫需要的歸檔列表。
run{
sql 'alter session setnls_date_format="yyyy-mm-dd hh24:mi:ss"';
set until time='2013-12-09:05:50:12';
restore database preview;
}
總結(jié)：
1 在對數(shù)據(jù)庫進(jìn)行恢復(fù)的時，第一步先看看數(shù)據(jù)庫是否歸檔，第二步看看數(shù)據(jù)庫是否有備份，第三步驗(yàn)證備份和歸檔的有效性。最后執(zhí)行整個恢復(fù)過程。
2 完全恢復(fù)時，通過對比restore database preview 顯示的歸檔列表seq號和聯(lián)機(jī)日志組的seq號，我們便可以清楚的推出數(shù)據(jù)庫完全恢復(fù)時，recover需要應(yīng)用的歸檔。
轉(zhuǎn)載于:https://blog.51cto.com/jiujian/1361353
總結(jié)
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