Oracle RMAN与Fuzzy模糊位

模糊位和恢复

ALTER SESSION SET EVENTS 'immediate trace name file_hdrs level 10';
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(From Oracle 11.2.x)
*DUMP OF DATA FILES: 209 files in database
*DATA FILE #1: ------------ NB: Here down is the control file info ---------
name #7: /grdbms/64bit/app/oracle/oradata/S112W6/system01.dbf
creation size=0 block size=8192 status=0xe head=7 tail=7 dup=1
==> ^^^^(kcc3.h)
KCCFEFDB 0x0001 /* file read-only, plugged from foreign DB */
KCCFEONL 0x0002 /* file is ONLine */
KCCFERDE 0x0004 /* ReaDing is Enabled */
KCCFECGE 0x0008 /* ChanGing is Enabled */
KCCFEMRR 0x0010 /* Media Recovery Required */
KCCFEGEM 0x0020 /* Generate End hot backup Marker at next open */
KCCFECKD 0x0040 /* File record generated by check dictionary */
KCCFESOR 0x0080 /* Save Offline scn Range at next checkpoint */
KCCFERMF 0x0100 /* Renamed Missing File */
KCCFEGOI 0x0200 /* Generate Off-line Immediate marker */
KCCFECUV 0x0400 /* Checkpoint by instance where UnVerified */
KCCFEDRP 0x0800 /* offline to be DRoPped */
KCCFEODC 0x2000 /* Online at Dictionary Check if read/only tblspc */
KCCFEDBR 0x4000 /* entry created by DBMS_BACKUP_RESTORE */
KCCFETRO 0x8000 /* Transition Read Only */define KCCFEWCC 0x1000 /*
tablespace 0, index=1 krfil=1 prev_file=0
unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00
Checkpoint cnt:254 scn: 0x0008.2fc2fcfc 05/29/2012 08:38:57
Stop scn: 0xffff.ffffffff 05/28/2012 22:12:14
==> ^^^Stop=ffff implies OPEN,ABORT or WARM
Creation Checkpointed at scn: 0x0000.00000007 09/05/2010 05:49:14
thread:0 rba:(0.0.0)
enabled threads: 00000000 00000000 00000000 00000000 00000000 00000000 ...
Offline scn: 0x0000.000edcac prev_range: 0
Online Checkpointed at scn: 0x0000.000edcad 04/19/2012 12:47:48
thread:1 rba:(0x1.2.0)
enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000
Hot Backup end marker scn: 0x0000.00000000
aux_file is NOT DEFINED
Plugged readony: NO
Plugin scnscn: 0x0000.00000000
Plugin resetlogs scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Foreign creation scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Foreign checkpoint scn/timescn: 0x0000.00000000 01/01/1988 00:00:00
Online move state: 0
* V10 STYLE FILE HEADER: ------------Here down is from the file header------------------
Compatibility Vsn = 186647040=0xb200200
^^^ Oldest Usable Oracle Vers
Db ID=4057569686=0xf1d99996, Db Name='S112W6'
Activation ID=0=0x0
Control Seq=4800=0x12c0, File size=129280=0x1f900
==> ^^^ Should be <= to Seq# in control file. File Number=1, Blksiz=2048, File Type=3 ==> ^^^^^^^^^^^(kcc4.h)
KCCTYPCF 1 /* control file */
KCCTYPRL 2 /* redo log file */
KCCTYPDF 3 /* vanilla db file */
KCCTYPBC 4 /* backup control file */
KCCTYPBP 5 /* backup piece */
KCCTYPTF 6 /* temporary db file */
KCCTYPCT 7 /* change tracking file */
KCCTYPFL 8 /* flashback database log file */
KCCTYPAL 9 /* archivelog file */
KCCTYPDC 10 /* datafile copy file */
KCCTYPIR 11 /* incompletely restored db file */
KCCTYPEL 12 /* foreign archivelog file */
KCCTYPLB 13 /* LOB */
Tablespace #0 - SYSTEM rel_fn:1
Creation at scn: 0x0000.00000007 09/05/2010 05:49:14
Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0
==>^^^^^ Last ALTER TABLESPACE BEGIN BACKUP
reset logs count:0x2e8d5a74 scn: 0x0000.000edcad
==>^^^^^ Last ALTER DATABASE OPEN RESETLOGS
prev reset logs count:0x2b920186 scn: 0x0000.000ed5f2
recovered at 05/14/2012 07:41:07
status:0x2004 root dba:0x00400208 chkpt cnt: 254 ctl cnt:253
==>^^^^^ (kcv3.h)
KCVFHHBP 0x01 /* hotbackup-in-progress on file (fuzzy file) */
KCVFHOFZ 0x04 /* Online FuZzy because it was online and db open */
KCVFHMFZ 0x10 /* Media recovery FuZzy - file in media recovery */
KCVFHAFZ 0x40 /* Absolutely FuZzy - fuzzyness from file scan */
KCVFH_FUZZY (KCVFHHBP|KCVFHOFZ|KCVFHMFZ|KCVFHAFZ|KCVFHPCP|KCVFHSBY)
KCVFH_OOFUZZY (KCVFHHBP|KCVFHMFZ|KCVFHAFZ|KCVFHPCP|KCVFHSBY)
KCVFH_NMFUZZY (KCVFH_FUZZY^KCVFHMFZ^KCVFHSBY) /* non-MR fuzzy */
KCVFHBCP 0x100 /* Bad Checkpoint - no enabled thread bitvec */
KCVFHFMH 0x200 /* Freshly Munged Header. resetlogs not finished */
KCVFHXCH 0x400 /* eXternally CacHed by operating system */
KCVFHZBA 0x800 /* Zeroed Blocks Allowed */
KCVFHPCP 0x1000 /* Proxy Copy in Progress */
KCVFHRBS 0x2000 /* does kcvfhrdb point to bootstrap$ ? */
KCVFHSBY 0x4000 /* media rcv fuzzy due to standby apply */
KCVFHL0C 0x8000 /* Incremental level 0 copy */
begin-hot-backup file size: 0
Checkpointed at scn: 0x0008.2fc2fcfc 05/29/2012 08:38:57
==>^^^^^ Last Datafile checkpoint & its REDO address.
thread:1 rba:(0x2e.34cb.10)
enabled threads: 01000000 00000000 00000000 00000000 00000000 00000000
==>^^^^^^ Threads of redo - thread 1 in use here
External cache id: 0x0 0x0 0x0 0x0
Absolute fuzzy scn: 0x0000.00000000
Recovery fuzzy scn: 0x0000.00000000 01/01/1988 00:00:00
Terminal Recovery Stamp 01/01/1988 00:00:00
Platform Information: Creation Platform ID: 13
Current Platform ID: 13 Last Platform ID: 13
==> ^^^^^^^^^ Check whether datafile has been transported from another platform
(splatform.h)
1 Solaris 32-bit
2 Solaris 64-bit
3 HP-UX (64-bit)
4 HP-UX IA (64-bit)
5 HP Tru64 UNIX
6 AIX-Based Sysetms (64-bit)
7 Microsoft Windows IA (32-bit)
8 Microsoft Windows IA (64-bit)
9 IBM zSeries Based Linux
10 Linux IA (32-bit)
11 Linux IA (64-bit)
12 Microsoft Windows x86 64-bit)
13 Linux x86 64-bit
14 IBM z/OS
15 HP Open VMs
16 Apple Mac OS
17 Solaris Operating System (x86)
18 IBM Power Based Linux
19 HP IA Open VMS
20 Solaris Operating System (x86-64)
21 Apple Mac OS (x86-64)

在数据文件头中的任何模糊位意味着，这个数据文件包含了SCN大于检查点的SCN的块。下面有4类型的模糊位存在于数据文件头。

1.在线 模糊（online fuzzy）
这个位被设置当数据库文件在正常数据库打开时。其被设置是因为DBWR可以写块从SGA到数据文件。这样会导致SCN可能在某些场合高于检查点SCN。其会在下面场景清理：
–数据文件关闭
–热备 fuzzy设置
–结束灾难恢复或结束结束恢复达到时
2.Hotbackup-Fuzzy

当执行alter tablespace begin backup命令的时候被设置。数据库文件头将被冻结并且块中包含SCN高于检查点SCN
当下面场景时清理：
–alter tablespace end backup或
Alter database end backup或
Alter database datafile 发布 end backup。结束灾难恢复或结束结束恢复达到时
3.介质恢复-Fuzzy

这个位在每个文件经历恢复开始恢复时被设置，并且其表明随着介质恢复进行，文件将包含当前头检查点后来的变更。
一般情况下，介质恢复模糊位可以在介质恢复检查点推荐到数据文件头时清理。
它们会在介质恢复会话成功完成或取消时被清理。

4.绝对模糊

当数据库是open状态，并且使用RMAN进行备份时，块发生变化时，绝对模糊位和绝对模糊SCN会被设置（热备）。在其他情况下的备份不会设置绝对模糊。
在文件头设置绝对模糊位和绝对模糊SCN

让RMAN在线备份进程从数据文件读取每个块时。它们从块缓存的头部获取到SCN，和当前绝对模糊SCN对比，这个SCN将被在文件头结构初始化设置为0，如果块的SCN更大，那么将拷贝块的SCN来作为文件头的绝对SCN。

这样的话，到文件结束时，这个绝对模糊SCN在文件头结构中包含的是整个数据文件块中的最高的SCN。

如果绝对模糊SCN高于数据文件的检查点SCN，那么其将维持绝对模糊SCN并且设置绝对模糊位。否则将简单的清理绝对模糊SCN，因为文件不需要应用redo来保证一致性。

所有的事情都由RMAN在目标实例上在通道中完成。

清理绝对模糊SCN

在恢复时，检查点将在日志边界处和结束介质恢复标记处发生。

在这个情况下，如果绝对模糊位设置了，并且如果检查点SCN大于或等于绝对模糊SCN，那么其将清理绝对模糊SCN并且清理绝对模糊位。在数据文件头中的绝对模糊SCN将被设置为0